/*

  * AVI demuxer

  * Copyright (c) 2001 Fabrice Bellard

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.

  *

  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */

 #include <inttypes.h>

 #include "libavutil/avassert.h"

 #include "libavutil/avstring.h"

 #include "libavutil/bswap.h"

 #include "libavutil/opt.h"

 #include "libavutil/dict.h"

 #include "libavutil/internal.h"

 #include "libavutil/intreadwrite.h"
 #include "libavutil/mathematics.h"

 #include "avformat.h"
 #include "avi.h"

 #include "dv.h"

 #include "internal.h"

 #include "isom.h"

 #include "riff.h"

 #include "libavcodec/bytestream.h"
 #include "libavcodec/exif.h"

 #include "libavcodec/internal.h"

 typedef struct AVIStream {

     int64_t frame_offset;   /* current frame (video) or byte (audio) counter
                              * (used to compute the pts) */

     int remaining;
     int packet_size;
 

     uint32_t handler;

     uint32_t scale;
     uint32_t rate;

     int sample_size;        /* size of one sample (or packet)
                              * (in the rate/scale sense) in bytes */

     int64_t cum_len;        /* temporary storage (used during seek) */
     int prefix;             /* normally 'd'<<8 + 'c' or 'w'<<8 + 'b' */

     int prefix_count;

     uint32_t pal[256];
     int has_pal;

     int dshow_block_align;  /* block align variable used to emulate bugs in
                              * the MS dshow demuxer */

 
     AVFormatContext *sub_ctx;
     AVPacket sub_pkt;
     uint8_t *sub_buffer;

 
     int64_t seek_pos;

 } AVIStream;

 typedef struct AVIContext {

     const AVClass *class;

     int64_t riff_end;
     int64_t movi_end;
     int64_t fsize;

     int64_t io_fsize;

     int64_t movi_list;

     int64_t last_pkt_pos;

     int index_loaded;

     int is_odml;

     int non_interleaved;
     int stream_index;

     DVDemuxContext *dv_demux;

     int odml_depth;

     int use_odml;

 #define MAX_ODML_DEPTH 1000

     int64_t dts_max;

 } AVIContext;
 

 
 static const AVOption options[] = {

     { "use_odml", "use odml index", offsetof(AVIContext, use_odml), AV_OPT_TYPE_BOOL, {.i64 = 1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},

     { NULL },
 };
 
 static const AVClass demuxer_class = {

     .class_name = "avi",

     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,

     .category   = AV_CLASS_CATEGORY_DEMUXER,

 };
 
 

 static const char avi_headers[][8] = {

     { 'R', 'I', 'F', 'F', 'A', 'V', 'I', ' '  },
     { 'R', 'I', 'F', 'F', 'A', 'V', 'I', 'X'  },
     { 'R', 'I', 'F', 'F', 'A', 'V', 'I', 0x19 },
     { 'O', 'N', '2', ' ', 'O', 'N', '2', 'f'  },
     { 'R', 'I', 'F', 'F', 'A', 'M', 'V', ' '  },

     { 0 }
 };
 

 static const AVMetadataConv avi_metadata_conv[] = {
     { "strn", "title" },
     { 0 },
 };
 

 static int avi_load_index(AVFormatContext *s);

 static int guess_ni_flag(AVFormatContext *s);

 #define print_tag(str, tag, size)                                      \
     av_log(NULL, AV_LOG_TRACE, "pos:%"PRIX64" %s: tag=%s size=0x%x\n", \
            avio_tell(pb), str, av_fourcc2str(tag), size)                  \

 static inline int get_duration(AVIStream *ast, int len)
 {
     if (ast->sample_size)

         return len;

     else if (ast->dshow_block_align)

         return (len + ast->dshow_block_align - 1) / ast->dshow_block_align;
     else

         return 1;
 }
 

 static int get_riff(AVFormatContext *s, AVIOContext *pb)

 {

     AVIContext *avi = s->priv_data;

     char header[8] = {0};

     int i;

     /* check RIFF header */

     avio_read(pb, header, 4);

     avi->riff_end  = avio_rl32(pb); /* RIFF chunk size */

     avi->riff_end += avio_tell(pb); /* RIFF chunk end */

     avio_read(pb, header + 4, 4);

     for (i = 0; avi_headers[i][0]; i++)
         if (!memcmp(header, avi_headers[i], 8))

             break;

     if (!avi_headers[i][0])

         return AVERROR_INVALIDDATA;

     if (header[7] == 0x19)
         av_log(s, AV_LOG_INFO,
                "This file has been generated by a totally broken muxer.\n");

     return 0;
 }
 

 static int read_odml_index(AVFormatContext *s, int frame_num)

 {
     AVIContext *avi     = s->priv_data;
     AVIOContext *pb     = s->pb;

     int longs_per_entry = avio_rl16(pb);

     int index_sub_type  = avio_r8(pb);
     int index_type      = avio_r8(pb);
     int entries_in_use  = avio_rl32(pb);
     int chunk_id        = avio_rl32(pb);
     int64_t base        = avio_rl64(pb);
     int stream_id       = ((chunk_id      & 0xFF) - '0') * 10 +
                           ((chunk_id >> 8 & 0xFF) - '0');

     AVStream *st;
     AVIStream *ast;
     int i;

     int64_t last_pos = -1;

     int64_t filesize = avi->fsize;

     av_log(s, AV_LOG_TRACE,

             "longs_per_entry:%d index_type:%d entries_in_use:%d "

             "chunk_id:%X base:%16"PRIX64" frame_num:%d\n",

             longs_per_entry,

             index_type,
             entries_in_use,
             chunk_id,

             base,
             frame_num);

 
     if (stream_id >= s->nb_streams || stream_id < 0)

         return AVERROR_INVALIDDATA;

     st  = s->streams[stream_id];

     ast = st->priv_data;
 

     if (index_sub_type)

         return AVERROR_INVALIDDATA;

     avio_rl32(pb);

     if (index_type && longs_per_entry != 2)

         return AVERROR_INVALIDDATA;

     if (index_type > 1)

         return AVERROR_INVALIDDATA;

     if (filesize > 0 && base >= filesize) {

         av_log(s, AV_LOG_ERROR, "ODML index invalid\n");

         if (base >> 32 == (base & 0xFFFFFFFF) &&
             (base & 0xFFFFFFFF) < filesize    &&
             filesize <= 0xFFFFFFFF)

             base &= 0xFFFFFFFF;
         else

             return AVERROR_INVALIDDATA;

     }
 

     for (i = 0; i < entries_in_use; i++) {
         if (index_type) {
             int64_t pos = avio_rl32(pb) + base - 8;
             int len     = avio_rl32(pb);
             int key     = len >= 0;

             len &= 0x7FFFFFFF;
 

             av_log(s, AV_LOG_TRACE, "pos:%"PRId64", len:%X\n", pos, len);

             if (avio_feof(pb))

                 return AVERROR_INVALIDDATA;

             if (last_pos == pos || pos == base - 8)
                 avi->non_interleaved = 1;

             if (last_pos != pos && len)

                 av_add_index_entry(st, pos, ast->cum_len, len, 0,
                                    key ? AVINDEX_KEYFRAME : 0);

             ast->cum_len += get_duration(ast, len);

             last_pos      = pos;
         } else {

             int64_t offset, pos;
             int duration;

             offset = avio_rl64(pb);
             avio_rl32(pb);       /* size */
             duration = avio_rl32(pb);

             if (avio_feof(pb))

                 return AVERROR_INVALIDDATA;

             pos = avio_tell(pb);

             if (avi->odml_depth > MAX_ODML_DEPTH) {

                 av_log(s, AV_LOG_ERROR, "Too deeply nested ODML indexes\n");

                 return AVERROR_INVALIDDATA;

             }
 

             if (avio_seek(pb, offset + 8, SEEK_SET) < 0)

                 return -1;

             avi->odml_depth++;

             read_odml_index(s, frame_num);

             avi->odml_depth--;

             frame_num += duration;
 

             if (avio_seek(pb, pos, SEEK_SET) < 0) {

                 av_log(s, AV_LOG_ERROR, "Failed to restore position after reading index\n");

                 return -1;
             }
 

         }
     }

     avi->index_loaded = 2;

     return 0;
 }
 

 static void clean_index(AVFormatContext *s)
 {

     int i;
     int64_t j;

     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st   = s->streams[i];

         AVIStream *ast = st->priv_data;

         int n          = st->nb_index_entries;
         int max        = ast->sample_size;

         int64_t pos, size, ts;
 

         if (n != 1 || ast->sample_size == 0)

             continue;
 

         while (max < 1024)
             max += max;

         pos  = st->index_entries[0].pos;
         size = st->index_entries[0].size;
         ts   = st->index_entries[0].timestamp;

         for (j = 0; j < size; j += max)
             av_add_index_entry(st, pos + j, ts + j, FFMIN(max, size - j), 0,
                                AVINDEX_KEYFRAME);

     }
 }
 

 static int avi_read_tag(AVFormatContext *s, AVStream *st, uint32_t tag,
                         uint32_t size)

 {

     AVIOContext *pb = s->pb;

     char key[5]     = { 0 };
     char *value;

     size += (size & 1);

     if (size == UINT_MAX)

         return AVERROR(EINVAL);

     value = av_malloc(size + 1);

     if (!value)

         return AVERROR(ENOMEM);

     if (avio_read(pb, value, size) != size)
         return AVERROR_INVALIDDATA;

     value[size] = 0;

     AV_WL32(key, tag);
 

     return av_dict_set(st ? &st->metadata : &s->metadata, key, value,

                        AV_DICT_DONT_STRDUP_VAL);

 }
 

 static const char months[12][4] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
                                     "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
 

 static void avi_metadata_creation_time(AVDictionary **metadata, char *date)

 {
     char month[4], time[9], buffer[64];
     int i, day, year;
     /* parse standard AVI date format (ie. "Mon Mar 10 15:04:43 2003") */
     if (sscanf(date, "%*3s%*[ ]%3s%*[ ]%2d%*[ ]%8s%*[ ]%4d",

                month, &day, time, &year) == 4) {

         for (i = 0; i < 12; i++)

             if (!av_strcasecmp(month, months[i])) {

                 snprintf(buffer, sizeof(buffer), "%.4d-%.2d-%.2d %s",

                          year, i + 1, day, time);

                 av_dict_set(metadata, "creation_time", buffer, 0);

             }

     } else if (date[4] == '/' && date[7] == '/') {
         date[4] = date[7] = '-';

         av_dict_set(metadata, "creation_time", date, 0);

     }

 }
 

 static void avi_read_nikon(AVFormatContext *s, uint64_t end)
 {

     while (avio_tell(s->pb) < end && !avio_feof(s->pb)) {

         uint32_t tag  = avio_rl32(s->pb);
         uint32_t size = avio_rl32(s->pb);

         switch (tag) {

         case MKTAG('n', 'c', 't', 'g'):  /* Nikon Tags */
         {

             uint64_t tag_end = avio_tell(s->pb) + size;

             while (avio_tell(s->pb) < tag_end && !avio_feof(s->pb)) {

                 uint16_t tag     = avio_rl16(s->pb);
                 uint16_t size    = avio_rl16(s->pb);

                 const char *name = NULL;

                 char buffer[64]  = { 0 };

                 size = FFMIN(size, tag_end - avio_tell(s->pb));

                 size -= avio_read(s->pb, buffer,

                                   FFMIN(size, sizeof(buffer) - 1));

                 switch (tag) {

                 case 0x03:
                     name = "maker";
                     break;
                 case 0x04:
                     name = "model";
                     break;
                 case 0x13:
                     name = "creation_time";

                     if (buffer[4] == ':' && buffer[7] == ':')
                         buffer[4] = buffer[7] = '-';
                     break;
                 }
                 if (name)

                     av_dict_set(&s->metadata, name, buffer, 0);

                 avio_skip(s->pb, size);

             }
             break;
         }
         default:

             avio_skip(s->pb, size);

             break;
         }
     }
 }
 

 static int avi_extract_stream_metadata(AVFormatContext *s, AVStream *st)

 {
     GetByteContext gb;

     uint8_t *data = st->codecpar->extradata;
     int data_size = st->codecpar->extradata_size;

     int tag, offset;
 
     if (!data || data_size < 8) {
         return AVERROR_INVALIDDATA;
     }
 
     bytestream2_init(&gb, data, data_size);
 
     tag = bytestream2_get_le32(&gb);
 
     switch (tag) {
     case MKTAG('A', 'V', 'I', 'F'):
         // skip 4 byte padding
         bytestream2_skip(&gb, 4);
         offset = bytestream2_tell(&gb);
         bytestream2_init(&gb, data + offset, data_size - offset);
 
         // decode EXIF tags from IFD, AVI is always little-endian

         return avpriv_exif_decode_ifd(s, &gb, 1, 0, &st->metadata);

         break;
     case MKTAG('C', 'A', 'S', 'I'):

         avpriv_request_sample(s, "RIFF stream data tag type CASI (%u)", tag);

         break;
     case MKTAG('Z', 'o', 'r', 'a'):

         avpriv_request_sample(s, "RIFF stream data tag type Zora (%u)", tag);

         break;
     default:
         break;
     }
 
     return 0;
 }
 

 static int calculate_bitrate(AVFormatContext *s)
 {
     AVIContext *avi = s->priv_data;
     int i, j;
     int64_t lensum = 0;
     int64_t maxpos = 0;
 
     for (i = 0; i<s->nb_streams; i++) {
         int64_t len = 0;
         AVStream *st = s->streams[i];
 
         if (!st->nb_index_entries)
             continue;
 
         for (j = 0; j < st->nb_index_entries; j++)
             len += st->index_entries[j].size;
         maxpos = FFMAX(maxpos, st->index_entries[j-1].pos);
         lensum += len;
     }

     if (maxpos < avi->io_fsize*9/10) // index does not cover the whole file

         return 0;
     if (lensum*9/10 > maxpos || lensum < maxpos*9/10) // frame sum and filesize mismatch
         return 0;
 
     for (i = 0; i<s->nb_streams; i++) {
         int64_t len = 0;
         AVStream *st = s->streams[i];
         int64_t duration;

         int64_t bitrate;

 
         for (j = 0; j < st->nb_index_entries; j++)
             len += st->index_entries[j].size;
 

         if (st->nb_index_entries < 2 || st->codecpar->bit_rate > 0)

             continue;
         duration = st->index_entries[j-1].timestamp - st->index_entries[0].timestamp;

         bitrate = av_rescale(8*len, st->time_base.den, duration * st->time_base.num);
         if (bitrate <= INT_MAX && bitrate > 0) {

             st->codecpar->bit_rate = bitrate;

         }

     }
     return 1;
 }
 

 static int avi_read_header(AVFormatContext *s)

 {

     AVIContext *avi = s->priv_data;

     AVIOContext *pb = s->pb;

     unsigned int tag, tag1, handler;

     int codec_type, stream_index, frame_period;

     unsigned int size;

     int i;

     AVStream *st;

     AVIStream *ast      = NULL;
     int avih_width      = 0, avih_height = 0;
     int amv_file_format = 0;
     uint64_t list_end   = 0;

     int64_t pos;

     int ret;

     AVDictionaryEntry *dict_entry;

     avi->stream_index = -1;

     ret = get_riff(s, pb);
     if (ret < 0)
         return ret;

     av_log(avi, AV_LOG_DEBUG, "use odml:%d\n", avi->use_odml);
 

     avi->io_fsize = avi->fsize = avio_size(pb);

     if (avi->fsize <= 0 || avi->fsize < avi->riff_end)

         avi->fsize = avi->riff_end == 8 ? INT64_MAX : avi->riff_end;

     /* first list tag */
     stream_index = -1;

     codec_type   = -1;

     frame_period = 0;

     for (;;) {

         if (avio_feof(pb))

             goto fail;

         tag  = avio_rl32(pb);

         size = avio_rl32(pb);

         print_tag("tag", tag, size);
 

         switch (tag) {

         case MKTAG('L', 'I', 'S', 'T'):

             list_end = avio_tell(pb) + size;

             /* Ignored, except at start of video packets. */

             tag1 = avio_rl32(pb);

             print_tag("list", tag1, 0);

             if (tag1 == MKTAG('m', 'o', 'v', 'i')) {

                 avi->movi_list = avio_tell(pb) - 4;

                 if (size)
                     avi->movi_end = avi->movi_list + size + (size & 1);
                 else

                     avi->movi_end = avi->fsize;

                 av_log(NULL, AV_LOG_TRACE, "movi end=%"PRIx64"\n", avi->movi_end);

                 goto end_of_header;

             } else if (tag1 == MKTAG('I', 'N', 'F', 'O'))

                 ff_read_riff_info(s, size - 4);

             else if (tag1 == MKTAG('n', 'c', 'd', 't'))
                 avi_read_nikon(s, list_end);

             break;

         case MKTAG('I', 'D', 'I', 'T'):
         {
             unsigned char date[64] = { 0 };

             size += (size & 1);

             size -= avio_read(pb, date, FFMIN(size, sizeof(date) - 1));

             avio_skip(pb, size);

             avi_metadata_creation_time(&s->metadata, date);
             break;
         }

         case MKTAG('d', 'm', 'l', 'h'):

             avi->is_odml = 1;

             avio_skip(pb, size + (size & 1));

             break;

         case MKTAG('a', 'm', 'v', 'h'):

             amv_file_format = 1;

         case MKTAG('a', 'v', 'i', 'h'):

             /* AVI header */

             /* using frame_period is bad idea */

             frame_period = avio_rl32(pb);

             avio_rl32(pb); /* max. bytes per second */

             avio_rl32(pb);
             avi->non_interleaved |= avio_rl32(pb) & AVIF_MUSTUSEINDEX;

             avio_skip(pb, 2 * 4);

             avio_rl32(pb);
             avio_rl32(pb);

             avih_width  = avio_rl32(pb);
             avih_height = avio_rl32(pb);

             avio_skip(pb, size - 10 * 4);

             break;
         case MKTAG('s', 't', 'r', 'h'):
             /* stream header */
 

             tag1    = avio_rl32(pb);

             handler = avio_rl32(pb); /* codec tag */

             if (tag1 == MKTAG('p', 'a', 'd', 's')) {

                 avio_skip(pb, size - 8);

                 break;

             } else {

                 stream_index++;

                 st = avformat_new_stream(s, NULL);

                 if (!st)
                     goto fail;

                 st->id = stream_index;

                 ast    = av_mallocz(sizeof(AVIStream));

                 if (!ast)
                     goto fail;
                 st->priv_data = ast;

             }

             if (amv_file_format)
                 tag1 = stream_index ? MKTAG('a', 'u', 'd', 's')
                                     : MKTAG('v', 'i', 'd', 's');

             print_tag("strh", tag1, -1);

             if (tag1 == MKTAG('i', 'a', 'v', 's') ||
                 tag1 == MKTAG('i', 'v', 'a', 's')) {

                 int64_t dv_dur;
 

                 /* After some consideration -- I don't think we
                  * have to support anything but DV in type1 AVIs. */

                 if (s->nb_streams != 1)
                     goto fail;
 
                 if (handler != MKTAG('d', 'v', 's', 'd') &&
                     handler != MKTAG('d', 'v', 'h', 'd') &&
                     handler != MKTAG('d', 'v', 's', 'l'))

                     goto fail;

 
                 ast = s->streams[0]->priv_data;

                 av_freep(&s->streams[0]->codecpar->extradata);
                 av_freep(&s->streams[0]->codecpar);

 #if FF_API_LAVF_AVCTX
 FF_DISABLE_DEPRECATION_WARNINGS

                 av_freep(&s->streams[0]->codec);

 FF_ENABLE_DEPRECATION_WARNINGS
 #endif

                 if (s->streams[0]->info)
                     av_freep(&s->streams[0]->info->duration_error);

                 av_freep(&s->streams[0]->info);

                 if (s->streams[0]->internal)
                     av_freep(&s->streams[0]->internal->avctx);
                 av_freep(&s->streams[0]->internal);

                 av_freep(&s->streams[0]);
                 s->nb_streams = 0;

                 if (CONFIG_DV_DEMUXER) {

                     avi->dv_demux = avpriv_dv_init_demux(s);

                     if (!avi->dv_demux)
                         goto fail;

                 } else
                     goto fail;

                 s->streams[0]->priv_data = ast;

                 avio_skip(pb, 3 * 4);

                 ast->scale = avio_rl32(pb);

                 ast->rate  = avio_rl32(pb);

                 avio_skip(pb, 4);  /* start time */

                 dv_dur = avio_rl32(pb);

                 if (ast->scale > 0 && ast->rate > 0 && dv_dur > 0) {

                     dv_dur     *= AV_TIME_BASE;

                     s->duration = av_rescale(dv_dur, ast->scale, ast->rate);
                 }

                 /* else, leave duration alone; timing estimation in utils.c
                  * will make a guess based on bitrate. */

                 stream_index = s->nb_streams - 1;

                 avio_skip(pb, size - 9 * 4);

                 break;
             }

             av_assert0(stream_index < s->nb_streams);

             ast->handler = handler;

             avio_rl32(pb); /* flags */
             avio_rl16(pb); /* priority */
             avio_rl16(pb); /* language */
             avio_rl32(pb); /* initial frame */
             ast->scale = avio_rl32(pb);

             ast->rate  = avio_rl32(pb);
             if (!(ast->scale && ast->rate)) {
                 av_log(s, AV_LOG_WARNING,

                        "scale/rate is %"PRIu32"/%"PRIu32" which is invalid. "

                        "(This file has been generated by broken software.)\n",
                        ast->scale,
                        ast->rate);
                 if (frame_period) {
                     ast->rate  = 1000000;

                     ast->scale = frame_period;

                 } else {
                     ast->rate  = 25;

                     ast->scale = 1;
                 }

             }

             avpriv_set_pts_info(st, 64, ast->scale, ast->rate);

             ast->cum_len  = avio_rl32(pb); /* start */

             st->nb_frames = avio_rl32(pb);

             st->start_time = 0;

             avio_rl32(pb); /* buffer size */
             avio_rl32(pb); /* quality */

             if (ast->cum_len > 3600LL * ast->rate / ast->scale) {

                 av_log(s, AV_LOG_ERROR, "crazy start time, iam scared, giving up\n");

                 ast->cum_len = 0;

             }

             ast->sample_size = avio_rl32(pb);

             ast->cum_len    *= FFMAX(1, ast->sample_size);

             av_log(s, AV_LOG_TRACE, "%"PRIu32" %"PRIu32" %d\n",

                     ast->rate, ast->scale, ast->sample_size);

             switch (tag1) {

             case MKTAG('v', 'i', 'd', 's'):

                 codec_type = AVMEDIA_TYPE_VIDEO;

                 ast->sample_size = 0;

                 st->avg_frame_rate = av_inv_q(st->time_base);

                 break;
             case MKTAG('a', 'u', 'd', 's'):

                 codec_type = AVMEDIA_TYPE_AUDIO;

                 break;

             case MKTAG('t', 'x', 't', 's'):

                 codec_type = AVMEDIA_TYPE_SUBTITLE;

                 break;

             case MKTAG('d', 'a', 't', 's'):

                 codec_type = AVMEDIA_TYPE_DATA;

                 break;

             default:

                 av_log(s, AV_LOG_INFO, "unknown stream type %X\n", tag1);

             }

 
             if (ast->sample_size < 0) {
                 if (s->error_recognition & AV_EF_EXPLODE) {
                     av_log(s, AV_LOG_ERROR,
                            "Invalid sample_size %d at stream %d\n",
                            ast->sample_size,
                            stream_index);
                     goto fail;
                 }
                 av_log(s, AV_LOG_WARNING,
                        "Invalid sample_size %d at stream %d "
                        "setting it to 0\n",
                        ast->sample_size,
                        stream_index);
                 ast->sample_size = 0;
             }
 

             if (ast->sample_size == 0) {

                 st->duration = st->nb_frames;

                 if (st->duration > 0 && avi->io_fsize > 0 && avi->riff_end > avi->io_fsize) {
                     av_log(s, AV_LOG_DEBUG, "File is truncated adjusting duration\n");
                     st->duration = av_rescale(st->duration, avi->io_fsize, avi->riff_end);
                 }
             }

             ast->frame_offset = ast->cum_len;

             avio_skip(pb, size - 12 * 4);

             break;
         case MKTAG('s', 't', 'r', 'f'):
             /* stream header */

             if (!size && (codec_type == AVMEDIA_TYPE_AUDIO ||
                           codec_type == AVMEDIA_TYPE_VIDEO))

                 break;

             if (stream_index >= (unsigned)s->nb_streams || avi->dv_demux) {

                 avio_skip(pb, size);

             } else {

                 uint64_t cur_pos = avio_tell(pb);

                 unsigned esize;

                 if (cur_pos < list_end)
                     size = FFMIN(size, list_end - cur_pos);

                 st = s->streams[stream_index];

                 if (st->codecpar->codec_type != AVMEDIA_TYPE_UNKNOWN) {

                     avio_skip(pb, size);
                     break;
                 }

                 switch (codec_type) {

                 case AVMEDIA_TYPE_VIDEO:

                     if (amv_file_format) {

                         st->codecpar->width      = avih_width;
                         st->codecpar->height     = avih_height;
                         st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
                         st->codecpar->codec_id   = AV_CODEC_ID_AMV;

                         avio_skip(pb, size);

                         break;
                     }

                     tag1 = ff_get_bmp_header(pb, st, &esize);

                     if (tag1 == MKTAG('D', 'X', 'S', 'B') ||
                         tag1 == MKTAG('D', 'X', 'S', 'A')) {

                         st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
                         st->codecpar->codec_tag  = tag1;
                         st->codecpar->codec_id   = AV_CODEC_ID_XSUB;

                         break;
                     }
 

                     if (size > 10 * 4 && size < (1 << 30) && size < avi->fsize) {
                         if (esize == size-1 && (esize&1)) {

                             st->codecpar->extradata_size = esize - 10 * 4;

                         } else

                             st->codecpar->extradata_size =  size - 10 * 4;

                         if (st->codecpar->extradata) {
                             av_log(s, AV_LOG_WARNING, "New extradata in strf chunk, freeing previous one.\n");
                             av_freep(&st->codecpar->extradata);
                         }

                         if (ff_get_extradata(s, st->codecpar, pb, st->codecpar->extradata_size) < 0)

                             return AVERROR(ENOMEM);

                     }

                     // FIXME: check if the encoder really did this correctly

                     if (st->codecpar->extradata_size & 1)

                         avio_r8(pb);

                     /* Extract palette from extradata if bpp <= 8.
                      * This code assumes that extradata contains only palette.
                      * This is true for all paletted codecs implemented in

                      * FFmpeg. */

                     if (st->codecpar->extradata_size &&
                         (st->codecpar->bits_per_coded_sample <= 8)) {
                         int pal_size = (1 << st->codecpar->bits_per_coded_sample) << 2;

                         const uint8_t *pal_src;
 

                         pal_size = FFMIN(pal_size, st->codecpar->extradata_size);
                         pal_src  = st->codecpar->extradata +
                                    st->codecpar->extradata_size - pal_size;

                         /* Exclude the "BottomUp" field from the palette */

                         if (pal_src - st->codecpar->extradata >= 9 &&
                             !memcmp(st->codecpar->extradata + st->codecpar->extradata_size - 9, "BottomUp", 9))

                             pal_src -= 9;

                         for (i = 0; i < pal_size / 4; i++)

                             ast->pal[i] = 0xFFU<<24 | AV_RL32(pal_src + 4 * i);

                         ast->has_pal = 1;

                     }
 

                     print_tag("video", tag1, 0);

                     st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
                     st->codecpar->codec_tag  = tag1;
                     st->codecpar->codec_id   = ff_codec_get_id(ff_codec_bmp_tags,

                                                             tag1);

                     /* If codec is not found yet, try with the mov tags. */

                     if (!st->codecpar->codec_id) {
                         st->codecpar->codec_id =

                             ff_codec_get_id(ff_codec_movvideo_tags, tag1);

                         if (st->codecpar->codec_id)

                            av_log(s, AV_LOG_WARNING,
                                   "mov tag found in avi (fourcc %s)\n",

                                   av_fourcc2str(tag1));

                     }

                     /* This is needed to get the pict type which is necessary
                      * for generating correct pts. */
                     st->need_parsing = AVSTREAM_PARSE_HEADERS;

                     if (st->codecpar->codec_id == AV_CODEC_ID_MPEG4 &&

                         ast->handler == MKTAG('X', 'V', 'I', 'D'))

                         st->codecpar->codec_tag = MKTAG('X', 'V', 'I', 'D');

                     if (st->codecpar->codec_tag == MKTAG('V', 'S', 'S', 'H'))

                         st->need_parsing = AVSTREAM_PARSE_FULL;

                     if (st->codecpar->codec_id == AV_CODEC_ID_RV40)

                         st->need_parsing = AVSTREAM_PARSE_NONE;

                     if (st->codecpar->codec_tag == 0 && st->codecpar->height > 0 &&
                         st->codecpar->extradata_size < 1U << 30) {
                         st->codecpar->extradata_size += 9;
                         if ((ret = av_reallocp(&st->codecpar->extradata,
                                                st->codecpar->extradata_size +

                                                AV_INPUT_BUFFER_PADDING_SIZE)) < 0) {

                             st->codecpar->extradata_size = 0;

                             return ret;

                         } else

                             memcpy(st->codecpar->extradata + st->codecpar->extradata_size - 9,

                                    "BottomUp", 9);

                     }

                     st->codecpar->height = FFABS(st->codecpar->height);

 //                    avio_skip(pb, size - 5 * 4);

                     break;

                 case AVMEDIA_TYPE_AUDIO:

                     ret = ff_get_wav_header(s, pb, st->codecpar, size, 0);

                     if (ret < 0)
                         return ret;

                     ast->dshow_block_align = st->codecpar->block_align;
                     if (ast->sample_size && st->codecpar->block_align &&
                         ast->sample_size != st->codecpar->block_align) {

                         av_log(s,
                                AV_LOG_WARNING,
                                "sample size (%d) != block align (%d)\n",
                                ast->sample_size,

                                st->codecpar->block_align);
                         ast->sample_size = st->codecpar->block_align;

                     }

                     /* 2-aligned
                      * (fix for Stargate SG-1 - 3x18 - Shades of Grey.avi) */
                     if (size & 1)

                         avio_skip(pb, 1);

                     /* Force parsing as several audio frames can be in

                      * one packet and timestamps refer to packet start. */

                     st->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;

                     /* ADTS header is in extradata, AAC without header must be
                      * stored as exact frames. Parser not needed and it will
                      * fail. */

                     if (st->codecpar->codec_id == AV_CODEC_ID_AAC &&
                         st->codecpar->extradata_size)

                         st->need_parsing = AVSTREAM_PARSE_NONE;

                     // The flac parser does not work with AVSTREAM_PARSE_TIMESTAMPS

                     if (st->codecpar->codec_id == AV_CODEC_ID_FLAC)

                         st->need_parsing = AVSTREAM_PARSE_NONE;

                     /* AVI files with Xan DPCM audio (wrongly) declare PCM
                      * audio in the header but have Axan as stream_code_tag. */

                     if (ast->handler == AV_RL32("Axan")) {

                         st->codecpar->codec_id  = AV_CODEC_ID_XAN_DPCM;
                         st->codecpar->codec_tag = 0;

                         ast->dshow_block_align = 0;

                     }

                     if (amv_file_format) {

                         st->codecpar->codec_id    = AV_CODEC_ID_ADPCM_IMA_AMV;

                         ast->dshow_block_align = 0;
                     }

                     if ((st->codecpar->codec_id == AV_CODEC_ID_AAC  ||
                          st->codecpar->codec_id == AV_CODEC_ID_FLAC ||
                          st->codecpar->codec_id == AV_CODEC_ID_MP2 ) && ast->dshow_block_align <= 4 && ast->dshow_block_align) {

                         av_log(s, AV_LOG_DEBUG, "overriding invalid dshow_block_align of %d\n", ast->dshow_block_align);
                         ast->dshow_block_align = 0;
                     }

                     if (st->codecpar->codec_id == AV_CODEC_ID_AAC && ast->dshow_block_align == 1024 && ast->sample_size == 1024 ||
                        st->codecpar->codec_id == AV_CODEC_ID_AAC && ast->dshow_block_align == 4096 && ast->sample_size == 4096 ||
                        st->codecpar->codec_id == AV_CODEC_ID_MP3 && ast->dshow_block_align == 1152 && ast->sample_size == 1152) {

                         av_log(s, AV_LOG_DEBUG, "overriding sample_size\n");

                         ast->sample_size = 0;
                     }

                     break;

                 case AVMEDIA_TYPE_SUBTITLE:

                     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;

                     st->request_probe= 1;

                     avio_skip(pb, size);

                     break;

                 default:

                     st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
                     st->codecpar->codec_id   = AV_CODEC_ID_NONE;
                     st->codecpar->codec_tag  = 0;

                     avio_skip(pb, size);

                     break;
                 }
             }
             break;

         case MKTAG('s', 't', 'r', 'd'):

             if (stream_index >= (unsigned)s->nb_streams

                 || s->streams[stream_index]->codecpar->extradata_size
                 || s->streams[stream_index]->codecpar->codec_tag == MKTAG('H','2','6','4')) {

                 avio_skip(pb, size);
             } else {
                 uint64_t cur_pos = avio_tell(pb);
                 if (cur_pos < list_end)
                     size = FFMIN(size, list_end - cur_pos);
                 st = s->streams[stream_index];
 

                 if (size<(1<<30)) {

                     if (st->codecpar->extradata) {
                         av_log(s, AV_LOG_WARNING, "New extradata in strd chunk, freeing previous one.\n");
                         av_freep(&st->codecpar->extradata);
                     }

                     if (ff_get_extradata(s, st->codecpar, pb, size) < 0)

                         return AVERROR(ENOMEM);
                 }
 

                 if (st->codecpar->extradata_size & 1) //FIXME check if the encoder really did this correctly

                     avio_r8(pb);

                 ret = avi_extract_stream_metadata(s, st);

                 if (ret < 0) {
                     av_log(s, AV_LOG_WARNING, "could not decoding EXIF data in stream header.\n");
                 }

             }
             break;

         case MKTAG('i', 'n', 'd', 'x'):

             pos = avio_tell(pb);

             if ((pb->seekable & AVIO_SEEKABLE_NORMAL) && !(s->flags & AVFMT_FLAG_IGNIDX) &&

                 avi->use_odml &&

                 read_odml_index(s, 0) < 0 &&

                 (s->error_recognition & AV_EF_EXPLODE))

                 goto fail;

             avio_seek(pb, pos + size, SEEK_SET);

             break;

         case MKTAG('v', 'p', 'r', 'p'):

             if (stream_index < (unsigned)s->nb_streams && size > 9 * 4) {

                 AVRational active, active_aspect;
 
                 st = s->streams[stream_index];

                 avio_rl32(pb);
                 avio_rl32(pb);
                 avio_rl32(pb);
                 avio_rl32(pb);
                 avio_rl32(pb);
 

                 active_aspect.den = avio_rl16(pb);
                 active_aspect.num = avio_rl16(pb);
                 active.num        = avio_rl32(pb);
                 active.den        = avio_rl32(pb);
                 avio_rl32(pb); // nbFieldsPerFrame

                 if (active_aspect.num && active_aspect.den &&
                     active.num && active.den) {
                     st->sample_aspect_ratio = av_div_q(active_aspect, active);

                     av_log(s, AV_LOG_TRACE, "vprp %d/%d %d/%d\n",

                             active_aspect.num, active_aspect.den,
                             active.num, active.den);

                 }

                 size -= 9 * 4;

             }

             avio_skip(pb, size);

             break;

         case MKTAG('s', 't', 'r', 'n'):

             if (s->nb_streams) {
                 ret = avi_read_tag(s, s->streams[s->nb_streams - 1], tag, size);

                 if (ret < 0)
                     return ret;

                 break;
             }

         default:

             if (size > 1000000) {
                 av_log(s, AV_LOG_ERROR,
                        "Something went wrong during header parsing, "

                        "tag %s has size %u, "
                        "I will ignore it and try to continue anyway.\n",

                        av_fourcc2str(tag), size);

                 if (s->error_recognition & AV_EF_EXPLODE)
                     goto fail;

                 avi->movi_list = avio_tell(pb) - 4;

                 avi->movi_end  = avi->fsize;

                 goto end_of_header;
             }

         /* Do not fail for very large idx1 tags */
         case MKTAG('i', 'd', 'x', '1'):

             /* skip tag */
             size += (size & 1);

             avio_skip(pb, size);

             break;
         }
     }

 
 end_of_header:

     /* check stream number */
     if (stream_index != s->nb_streams - 1) {

 
 fail:

         return AVERROR_INVALIDDATA;

     }

     if (!avi->index_loaded && (pb->seekable & AVIO_SEEKABLE_NORMAL))

         avi_load_index(s);

     calculate_bitrate(s);

     avi->index_loaded    |= 1;

 
     if ((ret = guess_ni_flag(s)) < 0)
         return ret;
 

     avi->non_interleaved |= ret | (s->flags & AVFMT_FLAG_SORT_DTS);

 
     dict_entry = av_dict_get(s->metadata, "ISFT", NULL, 0);
     if (dict_entry && !strcmp(dict_entry->value, "PotEncoder"))

         for (i = 0; i < s->nb_streams; i++) {

             AVStream *st = s->streams[i];

             if (   st->codecpar->codec_id == AV_CODEC_ID_MPEG1VIDEO
                 || st->codecpar->codec_id == AV_CODEC_ID_MPEG2VIDEO)

                 st->need_parsing = AVSTREAM_PARSE_FULL;
         }
 

     for (i = 0; i < s->nb_streams; i++) {

         AVStream *st = s->streams[i];

         if (st->nb_index_entries)

             break;
     }

     // DV-in-AVI cannot be non-interleaved, if set this must be
     // a mis-detection.

     if (avi->dv_demux)
         avi->non_interleaved = 0;

     if (i == s->nb_streams && avi->non_interleaved) {
         av_log(s, AV_LOG_WARNING,
                "Non-interleaved AVI without index, switching to interleaved\n");
         avi->non_interleaved = 0;

     }
 

     if (avi->non_interleaved) {

         av_log(s, AV_LOG_INFO, "non-interleaved AVI\n");

         clean_index(s);

     }

     ff_metadata_conv_ctx(s, NULL, avi_metadata_conv);
     ff_metadata_conv_ctx(s, NULL, ff_riff_info_conv);

     return 0;
 }
 

 static int read_gab2_sub(AVFormatContext *s, AVStream *st, AVPacket *pkt)

 {

     if (pkt->size >= 7 &&

         pkt->size < INT_MAX - AVPROBE_PADDING_SIZE &&

         !strcmp(pkt->data, "GAB2") && AV_RL16(pkt->data + 5) == 2) {

         uint8_t desc[256];

         int score      = AVPROBE_SCORE_EXTENSION, ret;

         AVIStream *ast = st->priv_data;
         AVInputFormat *sub_demuxer;
         AVRational time_base;

         int size;

         AVIOContext *pb = avio_alloc_context(pkt->data + 7,
                                              pkt->size - 7,
                                              0, NULL, NULL, NULL, NULL);

         AVProbeData pd;

         unsigned int desc_len = avio_rl32(pb);

         if (desc_len > pb->buf_end - pb->buf_ptr)
             goto error;

         ret = avio_get_str16le(pb, desc_len, desc, sizeof(desc));

         avio_skip(pb, desc_len - ret);

         if (*desc)

             av_dict_set(&st->metadata, "title", desc, 0);

         avio_rl16(pb);   /* flags? */
         avio_rl32(pb);   /* data size */

         size = pb->buf_end - pb->buf_ptr;
         pd = (AVProbeData) { .buf      = av_mallocz(size + AVPROBE_PADDING_SIZE),
                              .buf_size = size };
         if (!pd.buf)
             goto error;
         memcpy(pd.buf, pb->buf_ptr, size);
         sub_demuxer = av_probe_input_format2(&pd, 1, &score);
         av_freep(&pd.buf);
         if (!sub_demuxer)

             goto error;

         if (strcmp(sub_demuxer->name, "srt") && strcmp(sub_demuxer->name, "ass"))
             goto error;
 

         if (!(ast->sub_ctx = avformat_alloc_context()))
             goto error;
 

         ast->sub_ctx->pb = pb;

         if (ff_copy_whiteblacklists(ast->sub_ctx, s) < 0)

             goto error;

         if (!avformat_open_input(&ast->sub_ctx, "", sub_demuxer, NULL)) {

             if (ast->sub_ctx->nb_streams != 1)
                 goto error;

             ff_read_packet(ast->sub_ctx, &ast->sub_pkt);

             avcodec_parameters_copy(st->codecpar, ast->sub_ctx->streams[0]->codecpar);

             time_base = ast->sub_ctx->streams[0]->time_base;

             avpriv_set_pts_info(st, 64, time_base.num, time_base.den);

         }
         ast->sub_buffer = pkt->data;
         memset(pkt, 0, sizeof(*pkt));
         return 1;

 error:

         av_freep(&ast->sub_ctx);

         avio_context_free(&pb);

     }
     return 0;
 }
 
 static AVStream *get_subtitle_pkt(AVFormatContext *s, AVStream *next_st,
                                   AVPacket *pkt)
 {
     AVIStream *ast, *next_ast = next_st->priv_data;
     int64_t ts, next_ts, ts_min = INT64_MAX;
     AVStream *st, *sub_st = NULL;
     int i;
 
     next_ts = av_rescale_q(next_ast->frame_offset, next_st->time_base,
                            AV_TIME_BASE_Q);
 

     for (i = 0; i < s->nb_streams; i++) {

         st  = s->streams[i];
         ast = st->priv_data;

         if (st->discard < AVDISCARD_ALL && ast && ast->sub_pkt.data) {

             ts = av_rescale_q(ast->sub_pkt.dts, st->time_base, AV_TIME_BASE_Q);
             if (ts <= next_ts && ts < ts_min) {
                 ts_min = ts;
                 sub_st = st;
             }
         }
     }
 
     if (sub_st) {

         ast               = sub_st->priv_data;
         *pkt              = ast->sub_pkt;

         pkt->stream_index = sub_st->index;

         if (ff_read_packet(ast->sub_ctx, &ast->sub_pkt) < 0)

             ast->sub_pkt.data = NULL;
     }
     return sub_st;
 }
 

 static int get_stream_idx(const unsigned *d)

 {
     if (d[0] >= '0' && d[0] <= '9' &&
         d[1] >= '0' && d[1] <= '9') {

         return (d[0] - '0') * 10 + (d[1] - '0');

     } else {
         return 100; // invalid stream ID

     }
 }
 

 /**
  *
  * @param exit_early set to 1 to just gather packet position without making the changes needed to actually read & return the packet
  */

 static int avi_sync(AVFormatContext *s, int exit_early)

 {
     AVIContext *avi = s->priv_data;

     AVIOContext *pb = s->pb;

     int n;
     unsigned int d[8];

     unsigned int size;

     int64_t i, sync;

 
 start_sync:

     memset(d, -1, sizeof(d));

     for (i = sync = avio_tell(pb); !avio_feof(pb); i++) {

         int j;
 

         for (j = 0; j < 7; j++)
             d[j] = d[j + 1];
         d[7] = avio_r8(pb);

         size = d[4] + (d[5] << 8) + (d[6] << 16) + (d[7] << 24);

         n = get_stream_idx(d + 2);

         ff_tlog(s, "%X %X %X %X %X %X %X %X %"PRId64" %u %d\n",

                 d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7], i, size, n);

         if (i*(avi->io_fsize>0) + (uint64_t)size > avi->fsize || d[0] > 127)

             continue;
 

         // parse ix##
         if ((d[0] == 'i' && d[1] == 'x' && n < s->nb_streams) ||
             // parse JUNK
             (d[0] == 'J' && d[1] == 'U' && d[2] == 'N' && d[3] == 'K') ||

             (d[0] == 'i' && d[1] == 'd' && d[2] == 'x' && d[3] == '1') ||
             (d[0] == 'i' && d[1] == 'n' && d[2] == 'd' && d[3] == 'x')) {

             avio_skip(pb, size);
             goto start_sync;
         }
 

         // parse stray LIST
         if (d[0] == 'L' && d[1] == 'I' && d[2] == 'S' && d[3] == 'T') {

             avio_skip(pb, 4);
             goto start_sync;
         }
 

         n = get_stream_idx(d);

         if (!((i - avi->last_pkt_pos) & 1) &&
             get_stream_idx(d + 1) < s->nb_streams)

             continue;
 

         // detect ##ix chunk and skip
         if (d[2] == 'i' && d[3] == 'x' && n < s->nb_streams) {

             avio_skip(pb, size);
             goto start_sync;
         }
 

         if (avi->dv_demux && n != 0)
             continue;
 

         // parse ##dc/##wb
         if (n < s->nb_streams) {

             AVStream *st;
             AVIStream *ast;

             st  = s->streams[n];

             ast = st->priv_data;
 

             if (!ast) {

                 av_log(s, AV_LOG_WARNING, "Skipping foreign stream %d packet\n", n);

                 continue;
             }
 

             if (s->nb_streams >= 2) {
                 AVStream *st1   = s->streams[1];
                 AVIStream *ast1 = st1->priv_data;
                 // workaround for broken small-file-bug402.avi

                 if (   d[2] == 'w' && d[3] == 'b'
                    && n == 0

                    && st ->codecpar->codec_type == AVMEDIA_TYPE_VIDEO
                    && st1->codecpar->codec_type == AVMEDIA_TYPE_AUDIO

                    && ast->prefix == 'd'*256+'c'
                    && (d[2]*256+d[3] == ast1->prefix || !ast1->prefix_count)

                   ) {

                     n   = 1;
                     st  = st1;

                     ast = ast1;

                     av_log(s, AV_LOG_WARNING,
                            "Invalid stream + prefix combination, assuming audio.\n");

                 }
             }
 

             if (d[2] == 'p' && d[3] == 'c' && size <= 4 * 256 + 4) {
                 int k    = avio_r8(pb);

                 int last = (k + avio_r8(pb) - 1) & 0xFF;
 

                 avio_rl16(pb); // flags

                 // b + (g << 8) + (r << 16);

                 for (; k <= last; k++)

                     ast->pal[k] = 0xFFU<<24 | avio_rb32(pb)>>8;

                 ast->has_pal = 1;
                 goto start_sync;
             } else if (((ast->prefix_count < 5 || sync + 9 > i) &&
                         d[2] < 128 && d[3] < 128) ||
                        d[2] * 256 + d[3] == ast->prefix /* ||
                        (d[2] == 'd' && d[3] == 'c') ||
                        (d[2] == 'w' && d[3] == 'b') */) {

                 if (exit_early)
                     return 0;

                 if (d[2] * 256 + d[3] == ast->prefix)

                     ast->prefix_count++;

                 else {
                     ast->prefix       = d[2] * 256 + d[3];
                     ast->prefix_count = 0;

                 }
 

                 if (!avi->dv_demux &&
                     ((st->discard >= AVDISCARD_DEFAULT && size == 0) /* ||
                         // FIXME: needs a little reordering
                         (st->discard >= AVDISCARD_NONKEY &&
                         !(pkt->flags & AV_PKT_FLAG_KEY)) */
                     || st->discard >= AVDISCARD_ALL)) {
 
                     ast->frame_offset += get_duration(ast, size);
                     avio_skip(pb, size);
                     goto start_sync;
                 }
 

                 avi->stream_index = n;
                 ast->packet_size  = size + 8;
                 ast->remaining    = size;

                 if (size) {

                     uint64_t pos = avio_tell(pb) - 8;
                     if (!st->index_entries || !st->nb_index_entries ||
                         st->index_entries[st->nb_index_entries - 1].pos < pos) {
                         av_add_index_entry(st, pos, ast->frame_offset, size,
                                            0, AVINDEX_KEYFRAME);

                     }
                 }
                 return 0;
             }
         }
     }
 

     if (pb->error)

         return pb->error;

     return AVERROR_EOF;
 }
 

 static int ni_prepare_read(AVFormatContext *s)
 {
     AVIContext *avi = s->priv_data;
     int best_stream_index = 0;
     AVStream *best_st     = NULL;
     AVIStream *best_ast;
     int64_t best_ts = INT64_MAX;
     int i;
 
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st   = s->streams[i];
         AVIStream *ast = st->priv_data;
         int64_t ts     = ast->frame_offset;
         int64_t last_ts;
 
         if (!st->nb_index_entries)
             continue;
 
         last_ts = st->index_entries[st->nb_index_entries - 1].timestamp;
         if (!ast->remaining && ts > last_ts)
             continue;
 
         ts = av_rescale_q(ts, st->time_base,
                           (AVRational) { FFMAX(1, ast->sample_size),
                                          AV_TIME_BASE });
 
         av_log(s, AV_LOG_TRACE, "%"PRId64" %d/%d %"PRId64"\n", ts,
                 st->time_base.num, st->time_base.den, ast->frame_offset);
         if (ts < best_ts) {
             best_ts           = ts;
             best_st           = st;
             best_stream_index = i;
         }
     }
     if (!best_st)
         return AVERROR_EOF;
 
     best_ast = best_st->priv_data;

     best_ts  = best_ast->frame_offset;

     if (best_ast->remaining) {
         i = av_index_search_timestamp(best_st,
                                       best_ts,
                                       AVSEEK_FLAG_ANY |
                                       AVSEEK_FLAG_BACKWARD);
     } else {
         i = av_index_search_timestamp(best_st, best_ts, AVSEEK_FLAG_ANY);
         if (i >= 0)
             best_ast->frame_offset = best_st->index_entries[i].timestamp;
     }
 
     if (i >= 0) {
         int64_t pos = best_st->index_entries[i].pos;
         pos += best_ast->packet_size - best_ast->remaining;

         if (avio_seek(s->pb, pos + 8, SEEK_SET) < 0)
           return AVERROR_EOF;

         av_assert0(best_ast->remaining <= best_ast->packet_size);

 
         avi->stream_index = best_stream_index;
         if (!best_ast->remaining)
             best_ast->packet_size =
             best_ast->remaining   = best_st->index_entries[i].size;
     }

     else
         return AVERROR_EOF;

 
     return 0;
 }
 

 static int avi_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     AVIContext *avi = s->priv_data;
     AVIOContext *pb = s->pb;
     int err;

     if (CONFIG_DV_DEMUXER && avi->dv_demux) {

         int size = avpriv_dv_get_packet(avi->dv_demux, pkt);

         if (size >= 0)
             return size;

         else
             goto resync;

     }

     if (avi->non_interleaved) {

         err = ni_prepare_read(s);
         if (err < 0)
             return err;

     }

 resync:

     if (avi->stream_index >= 0) {
         AVStream *st   = s->streams[avi->stream_index];
         AVIStream *ast = st->priv_data;

         int size, err;

         if (get_subtitle_pkt(s, st, pkt))

             return 0;
 

         // minorityreport.AVI block_align=1024 sample_size=1 IMA-ADPCM
         if (ast->sample_size <= 1)
             size = INT_MAX;
         else if (ast->sample_size < 32)

             // arbitrary multiplier to avoid tiny packets for raw PCM data

             size = 1024 * ast->sample_size;

         else

             size = ast->sample_size;

         if (size > ast->remaining)
             size = ast->remaining;
         avi->last_pkt_pos = avio_tell(pb);
         err               = av_get_packet(pb, pkt, size);
         if (err < 0)

             return err;

         size = err;

         if (ast->has_pal && pkt->size < (unsigned)INT_MAX / 2) {

             uint8_t *pal;

             pal = av_packet_new_side_data(pkt,
                                           AV_PKT_DATA_PALETTE,
                                           AVPALETTE_SIZE);
             if (!pal) {
                 av_log(s, AV_LOG_ERROR,
                        "Failed to allocate data for palette\n");
             } else {

                 memcpy(pal, ast->pal, AVPALETTE_SIZE);
                 ast->has_pal = 0;
             }

         }
 

         if (CONFIG_DV_DEMUXER && avi->dv_demux) {

             AVBufferRef *avbuf = pkt->buf;

             size = avpriv_dv_produce_packet(avi->dv_demux, pkt,

                                             pkt->data, pkt->size, pkt->pos);

             pkt->buf    = avbuf;

             pkt->flags |= AV_PKT_FLAG_KEY;

             if (size < 0)

                 av_packet_unref(pkt);

         } else if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE &&

                    !st->codecpar->codec_tag && read_gab2_sub(s, st, pkt)) {

             ast->frame_offset++;
             avi->stream_index = -1;

             ast->remaining    = 0;

             goto resync;

         } else {

             /* XXX: How to handle B-frames in AVI? */

             pkt->dts = ast->frame_offset;
 //                pkt->dts += ast->start;

             if (ast->sample_size)

                 pkt->dts /= ast->sample_size;
             pkt->stream_index = avi->stream_index;
 

             if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && st->index_entries) {

                 AVIndexEntry *e;
                 int index;

                 index = av_index_search_timestamp(st, ast->frame_offset, AVSEEK_FLAG_ANY);

                 e     = &st->index_entries[index];

                 if (index >= 0 && e->timestamp == ast->frame_offset) {
                     if (index == st->nb_index_entries-1) {

                         int key=1;
                         uint32_t state=-1;

                         if (st->codecpar->codec_id == AV_CODEC_ID_MPEG4) {

                             const uint8_t *ptr = pkt->data, *end = ptr + FFMIN(size, 256);
                             while (ptr < end) {
                                 ptr = avpriv_find_start_code(ptr, end, &state);
                                 if (state == 0x1B6 && ptr < end) {
                                     key = !(*ptr & 0xC0);

                                     break;
                                 }

                             }

                         }

                         if (!key)

                             e->flags &= ~AVINDEX_KEYFRAME;
                     }

                     if (e->flags & AVINDEX_KEYFRAME)

                         pkt->flags |= AV_PKT_FLAG_KEY;

                 }

             } else {

                 pkt->flags |= AV_PKT_FLAG_KEY;

             }

             ast->frame_offset += get_duration(ast, pkt->size);

         }

         ast->remaining -= err;

         if (!ast->remaining) {
             avi->stream_index = -1;
             ast->packet_size  = 0;

         }
 

         if (!avi->non_interleaved && pkt->pos >= 0 && ast->seek_pos > pkt->pos) {

             av_packet_unref(pkt);

             goto resync;
         }
         ast->seek_pos= 0;
 

         if (!avi->non_interleaved && st->nb_index_entries>1 && avi->index_loaded>1) {

             int64_t dts= av_rescale_q(pkt->dts, st->time_base, AV_TIME_BASE_Q);
 

             if (avi->dts_max - dts > 2*AV_TIME_BASE) {

                 avi->non_interleaved= 1;
                 av_log(s, AV_LOG_INFO, "Switching to NI mode, due to poor interleaving\n");

             }else if (avi->dts_max < dts)

                 avi->dts_max = dts;
         }
 

         return 0;

     }
 

     if ((err = avi_sync(s, 0)) < 0)

         return err;
     goto resync;

 }
 

 /* XXX: We make the implicit supposition that the positions are sorted

  * for each stream. */

 static int avi_read_idx1(AVFormatContext *s, int size)
 {

     AVIContext *avi = s->priv_data;

     AVIOContext *pb = s->pb;

     int nb_index_entries, i;
     AVStream *st;
     AVIStream *ast;

     int64_t pos;
     unsigned int index, tag, flags, len, first_packet = 1;
     int64_t last_pos = -1;

     unsigned last_idx = -1;

     int64_t idx1_pos, first_packet_pos = 0, data_offset = 0;

     int anykey = 0;

     nb_index_entries = size / 16;
     if (nb_index_entries <= 0)

         return AVERROR_INVALIDDATA;

     idx1_pos = avio_tell(pb);

     avio_seek(pb, avi->movi_list + 4, SEEK_SET);
     if (avi_sync(s, 1) == 0)

         first_packet_pos = avio_tell(pb) - 8;
     avi->stream_index = -1;
     avio_seek(pb, idx1_pos, SEEK_SET);
 

     if (s->nb_streams == 1 && s->streams[0]->codecpar->codec_tag == AV_RL32("MMES")) {

         first_packet_pos = 0;
         data_offset = avi->movi_list;
     }
 

     /* Read the entries and sort them in each stream component. */

     for (i = 0; i < nb_index_entries; i++) {

         if (avio_feof(pb))

             return -1;
 

         tag   = avio_rl32(pb);

         flags = avio_rl32(pb);

         pos   = avio_rl32(pb);
         len   = avio_rl32(pb);

         av_log(s, AV_LOG_TRACE, "%d: tag=0x%x flags=0x%x pos=0x%"PRIx64" len=%d/",

                 i, tag, flags, pos, len);

         index  = ((tag      & 0xff) - '0') * 10;
         index +=  (tag >> 8 & 0xff) - '0';

         if (index >= s->nb_streams)
             continue;

         st  = s->streams[index];

         ast = st->priv_data;

         /* Skip 'xxpc' palette change entries in the index until a logic
          * to process these is properly implemented. */

         if ((tag >> 16 & 0xff) == 'p' && (tag >> 24 & 0xff) == 'c')
             continue;
 

         if (first_packet && first_packet_pos) {

             if (avi->movi_list + 4 != pos || pos + 500 > first_packet_pos)
                 data_offset  = first_packet_pos - pos;

             first_packet = 0;
         }
         pos += data_offset;
 

         av_log(s, AV_LOG_TRACE, "%d cum_len=%"PRId64"\n", len, ast->cum_len);

         // even if we have only a single stream, we should
         // switch to non-interleaved to get correct timestamps

         if (last_pos == pos)
             avi->non_interleaved = 1;

         if (last_idx != pos && len) {

             av_add_index_entry(st, pos, ast->cum_len, len, 0,
                                (flags & AVIIF_INDEX) ? AVINDEX_KEYFRAME : 0);

             last_idx= pos;

         }

         ast->cum_len += get_duration(ast, len);

         last_pos      = pos;

         anykey       |= flags&AVIIF_INDEX;

     }
     if (!anykey) {
         for (index = 0; index < s->nb_streams; index++) {
             st = s->streams[index];
             if (st->nb_index_entries)
                 st->index_entries[0].flags |= AVINDEX_KEYFRAME;
         }

     }
     return 0;
 }
 

 /* Scan the index and consider any file with streams more than
  * 2 seconds or 64MB apart non-interleaved. */
 static int check_stream_max_drift(AVFormatContext *s)
 {
     int64_t min_pos, pos;
     int i;
     int *idx = av_mallocz_array(s->nb_streams, sizeof(*idx));
     if (!idx)
         return AVERROR(ENOMEM);
     for (min_pos = pos = 0; min_pos != INT64_MAX; pos = min_pos + 1LU) {
         int64_t max_dts = INT64_MIN / 2;
         int64_t min_dts = INT64_MAX / 2;
         int64_t max_buffer = 0;
 
         min_pos = INT64_MAX;
 
         for (i = 0; i < s->nb_streams; i++) {
             AVStream *st = s->streams[i];
             AVIStream *ast = st->priv_data;
             int n = st->nb_index_entries;
             while (idx[i] < n && st->index_entries[idx[i]].pos < pos)
                 idx[i]++;
             if (idx[i] < n) {
                 int64_t dts;
                 dts = av_rescale_q(st->index_entries[idx[i]].timestamp /
                                    FFMAX(ast->sample_size, 1),
                                    st->time_base, AV_TIME_BASE_Q);
                 min_dts = FFMIN(min_dts, dts);
                 min_pos = FFMIN(min_pos, st->index_entries[idx[i]].pos);
             }
         }
         for (i = 0; i < s->nb_streams; i++) {
             AVStream *st = s->streams[i];
             AVIStream *ast = st->priv_data;
 
             if (idx[i] && min_dts != INT64_MAX / 2) {
                 int64_t dts;
                 dts = av_rescale_q(st->index_entries[idx[i] - 1].timestamp /
                                    FFMAX(ast->sample_size, 1),
                                    st->time_base, AV_TIME_BASE_Q);
                 max_dts = FFMAX(max_dts, dts);
                 max_buffer = FFMAX(max_buffer,
                                    av_rescale(dts - min_dts,

                                               st->codecpar->bit_rate,

                                               AV_TIME_BASE));
             }
         }
         if (max_dts - min_dts > 2 * AV_TIME_BASE ||
             max_buffer > 1024 * 1024 * 8 * 8) {
             av_free(idx);
             return 1;
         }
     }
     av_free(idx);
     return 0;
 }
 

 static int guess_ni_flag(AVFormatContext *s)
 {

     int i;

     int64_t last_start = 0;
     int64_t first_end  = INT64_MAX;
     int64_t oldpos     = avio_tell(s->pb);

     for (i = 0; i < s->nb_streams; i++) {

         AVStream *st = s->streams[i];

         int n        = st->nb_index_entries;

         unsigned int size;

         if (n <= 0)

             continue;
 

         if (n >= 2) {
             int64_t pos = st->index_entries[0].pos;

             unsigned tag[2];
             avio_seek(s->pb, pos, SEEK_SET);
             tag[0] = avio_r8(s->pb);
             tag[1] = avio_r8(s->pb);
             avio_rl16(s->pb);

             size = avio_rl32(s->pb);

             if (get_stream_idx(tag) == i && pos + size > st->index_entries[1].pos)

                 last_start = INT64_MAX;

             if (get_stream_idx(tag) == i && size == st->index_entries[0].size + 8)
                 last_start = INT64_MAX;

         }
 

         if (st->index_entries[0].pos > last_start)
             last_start = st->index_entries[0].pos;
         if (st->index_entries[n - 1].pos < first_end)
             first_end = st->index_entries[n - 1].pos;

     }

     avio_seek(s->pb, oldpos, SEEK_SET);

     if (last_start > first_end)
         return 1;
 

     return check_stream_max_drift(s);

 }
 

 static int avi_load_index(AVFormatContext *s)
 {
     AVIContext *avi = s->priv_data;

     AVIOContext *pb = s->pb;

     uint32_t tag, size;

     int64_t pos = avio_tell(pb);

     int64_t next;

     int ret     = -1;

     if (avio_seek(pb, avi->movi_end, SEEK_SET) < 0)

         goto the_end; // maybe truncated file

     av_log(s, AV_LOG_TRACE, "movi_end=0x%"PRIx64"\n", avi->movi_end);

     for (;;) {
         tag  = avio_rl32(pb);

         size = avio_rl32(pb);

         if (avio_feof(pb))

             break;
         next = avio_tell(pb) + size + (size & 1);
 

         if (tag == MKTAG('i', 'd', 'x', '1') &&
             avi_read_idx1(s, size) >= 0) {

             avi->index_loaded=2;

             ret = 0;

         }else if (tag == MKTAG('L', 'I', 'S', 'T')) {

             uint32_t tag1 = avio_rl32(pb);
 
             if (tag1 == MKTAG('I', 'N', 'F', 'O'))
                 ff_read_riff_info(s, size - 4);

         }else if (!ret)

             break;

         if (avio_seek(pb, next, SEEK_SET) < 0)

             break; // something is wrong here

     }

 
 the_end:

     avio_seek(pb, pos, SEEK_SET);

     return ret;

 }
 

 static void seek_subtitle(AVStream *st, AVStream *st2, int64_t timestamp)
 {
     AVIStream *ast2 = st2->priv_data;

     int64_t ts2     = av_rescale_q(timestamp, st->time_base, st2->time_base);

     av_packet_unref(&ast2->sub_pkt);

     if (avformat_seek_file(ast2->sub_ctx, 0, INT64_MIN, ts2, ts2, 0) >= 0 ||
         avformat_seek_file(ast2->sub_ctx, 0, ts2, ts2, INT64_MAX, 0) >= 0)

         ff_read_packet(ast2->sub_ctx, &ast2->sub_pkt);

 }
 

 static int avi_read_seek(AVFormatContext *s, int stream_index,
                          int64_t timestamp, int flags)

 {
     AVIContext *avi = s->priv_data;
     AVStream *st;

     int i, index;

     int64_t pos, pos_min;

     AVIStream *ast;

     /* Does not matter which stream is requested dv in avi has the
      * stream information in the first video stream.
      */
     if (avi->dv_demux)
         stream_index = 0;
 

     if (!avi->index_loaded) {
         /* we only load the index on demand */
         avi_load_index(s);

         avi->index_loaded |= 1;

     }

     av_assert0(stream_index >= 0);

 
     st    = s->streams[stream_index];
     ast   = st->priv_data;
     index = av_index_search_timestamp(st,
                                       timestamp * FFMAX(ast->sample_size, 1),
                                       flags);

     if (index < 0) {

         if (st->nb_index_entries > 0)

             av_log(s, AV_LOG_DEBUG, "Failed to find timestamp %"PRId64 " in index %"PRId64 " .. %"PRId64 "\n",

                    timestamp * FFMAX(ast->sample_size, 1),
                    st->index_entries[0].timestamp,
                    st->index_entries[st->nb_index_entries - 1].timestamp);

         return AVERROR_INVALIDDATA;

     }

     /* find the position */

     pos       = st->index_entries[index].pos;

     timestamp = st->index_entries[index].timestamp / FFMAX(ast->sample_size, 1);

     av_log(s, AV_LOG_TRACE, "XX %"PRId64" %d %"PRId64"\n",

             timestamp, index, st->index_entries[index].timestamp);

     if (CONFIG_DV_DEMUXER && avi->dv_demux) {

         /* One and only one real stream for DV in AVI, and it has video  */

         /* offsets. Calling with other stream indexes should have failed */

         /* the av_index_search_timestamp call above.                     */
 

         if (avio_seek(s->pb, pos, SEEK_SET) < 0)

             return -1;
 

         /* Feed the DV video stream version of the timestamp to the */

         /* DV demux so it can synthesize correct timestamps.        */

         ff_dv_offset_reset(avi->dv_demux, timestamp);

         avi->stream_index = -1;

         return 0;
     }
 

     pos_min = pos;

     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st2   = s->streams[i];

         AVIStream *ast2 = st2->priv_data;

         ast2->packet_size =
         ast2->remaining   = 0;

         if (ast2->sub_ctx) {
             seek_subtitle(st, st2, timestamp);
             continue;
         }
 

         if (st2->nb_index_entries <= 0)
             continue;

 //        av_assert1(st2->codecpar->block_align);

         index = av_index_search_timestamp(st2,
                                           av_rescale_q(timestamp,
                                                        st->time_base,
                                                        st2->time_base) *
                                           FFMAX(ast2->sample_size, 1),

                                           flags |
                                           AVSEEK_FLAG_BACKWARD |

                                           (st2->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ? AVSEEK_FLAG_ANY : 0));

         if (index < 0)
             index = 0;

         ast2->seek_pos = st2->index_entries[index].pos;
         pos_min = FFMIN(pos_min,ast2->seek_pos);

     }

     for (i = 0; i < s->nb_streams; i++) {

         AVStream *st2 = s->streams[i];
         AVIStream *ast2 = st2->priv_data;
 
         if (ast2->sub_ctx || st2->nb_index_entries <= 0)
             continue;
 
         index = av_index_search_timestamp(
                 st2,
                 av_rescale_q(timestamp, st->time_base, st2->time_base) * FFMAX(ast2->sample_size, 1),

                 flags | AVSEEK_FLAG_BACKWARD | (st2->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ? AVSEEK_FLAG_ANY : 0));

         if (index < 0)
             index = 0;
         while (!avi->non_interleaved && index>0 && st2->index_entries[index-1].pos >= pos_min)

             index--;

         ast2->frame_offset = st2->index_entries[index].timestamp;

     }

     /* do the seek */

     if (avio_seek(s->pb, pos_min, SEEK_SET) < 0) {
         av_log(s, AV_LOG_ERROR, "Seek failed\n");

         return -1;

     }

     avi->stream_index = -1;

     avi->dts_max      = INT_MIN;

     return 0;
 }
 

 static int avi_read_close(AVFormatContext *s)

 {

     int i;
     AVIContext *avi = s->priv_data;
 

     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st   = s->streams[i];

         AVIStream *ast = st->priv_data;

         if (ast) {

             if (ast->sub_ctx) {
                 av_freep(&ast->sub_ctx->pb);

                 avformat_close_input(&ast->sub_ctx);

             }

             av_freep(&ast->sub_buffer);

             av_packet_unref(&ast->sub_pkt);

         }

     }
 

     av_freep(&avi->dv_demux);

     return 0;
 }
 
 static int avi_probe(AVProbeData *p)
 {

     int i;
 

     /* check file header */

     for (i = 0; avi_headers[i][0]; i++)

         if (AV_RL32(p->buf    ) == AV_RL32(avi_headers[i]    ) &&
             AV_RL32(p->buf + 8) == AV_RL32(avi_headers[i] + 4))

             return AVPROBE_SCORE_MAX;
 
     return 0;

 }
 

 AVInputFormat ff_avi_demuxer = {

     .name           = "avi",

     .long_name      = NULL_IF_CONFIG_SMALL("AVI (Audio Video Interleaved)"),

     .priv_data_size = sizeof(AVIContext),

     .extensions     = "avi",

     .read_probe     = avi_probe,
     .read_header    = avi_read_header,
     .read_packet    = avi_read_packet,
     .read_close     = avi_read_close,
     .read_seek      = avi_read_seek,

     .priv_class = &demuxer_class,

 };