/*

  * 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 "libavutil/intreadwrite.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/bswap.h"

 #include "libavutil/opt.h"

 #include "libavutil/dict.h"

 #include "libavutil/avstring.h"

 #include "avformat.h"

 #include "internal.h"

 #include "avi.h"

 #include "dv.h"

 #include "riff.h"

 #undef NDEBUG
 #include <assert.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;
 

     int scale;

     int 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 {

     const AVClass *class;

     int64_t  riff_end;
     int64_t  movi_end;

     int64_t  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_INT, {.dbl = 1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},

     { NULL },
 };
 
 static const AVClass demuxer_class = {
     "AVI demuxer",
     av_default_item_name,
     options,
     LIBAVUTIL_VERSION_INT,
 };
 
 

 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_dlog(NULL, "%s: tag=%c%c%c%c size=0x%x\n",       \

            str, tag & 0xff,                             \
            (tag >> 8) & 0xff,                           \
            (tag >> 16) & 0xff,                          \
            (tag >> 24) & 0xff,                          \
            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];
     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 -1;

     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_braindead_odml_indx(AVFormatContext *s, int frame_num){

     AVIContext *avi = s->priv_data;

     AVIOContext *pb = s->pb;

     int longs_pre_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= 10*((chunk_id&0xFF) - '0') + (((chunk_id>>8)&0xFF) - '0');
     AVStream *st;
     AVIStream *ast;
     int i;

     int64_t last_pos= -1;

     int64_t filesize= avi->fsize;

     av_dlog(s, "longs_pre_entry:%d index_type:%d entries_in_use:%d chunk_id:%X base:%16"PRIX64"\n",
             longs_pre_entry,index_type, entries_in_use, chunk_id, base);

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

         return -1;
     st= s->streams[stream_id];
     ast = st->priv_data;
 
     if(index_sub_type)
         return -1;
 

     avio_rl32(pb);

 
     if(index_type && longs_pre_entry != 2)
         return -1;
     if(index_type>1)
         return -1;
 

     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 -1;
     }
 

     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;
 

 #ifdef DEBUG_SEEK

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

 #endif

             if(url_feof(pb))
                 return -1;
 

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

             if(last_pos != pos && (len || !ast->sample_size))

                 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(url_feof(pb))
                 return -1;
 

             pos = avio_tell(pb);

             if(avi->odml_depth > MAX_ODML_DEPTH){
                 av_log(s, AV_LOG_ERROR, "Too deeply nested ODML indexes\n");
                 return -1;
             }
 

             if(avio_seek(pb, offset+8, SEEK_SET) < 0)
                 return -1;

             avi->odml_depth++;

             read_braindead_odml_indx(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");
                 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}, *value;

     size += (size & 1);

     if (size == UINT_MAX)
         return -1;
     value = av_malloc(size+1);
     if (!value)
         return -1;

     avio_read(pb, value, size);

     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) {

         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) {

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

                 const char *name = NULL;
                 char buffer[64] = {0};

                 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_read_header(AVFormatContext *s, AVFormatParameters *ap)

 {

     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;

     int ret;

     avi->stream_index= -1;

     if (get_riff(s, pb) < 0)

         return -1;

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

     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 (url_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_dlog(NULL, "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]->codec->extradata);

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

                 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;

                 }

                 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;
             }

             assert(stream_index < s->nb_streams);

             st->codec->stream_codec_tag= 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 %u/%u 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*ast->scale/ast->rate > 3600) {
                 av_log(s, AV_LOG_ERROR, "crazy start time, iam scared, giving up\n");
                 return AVERROR_INVALIDDATA;
             }

             ast->sample_size = avio_rl32(pb); /* sample ssize */

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

 //            av_log(s, AV_LOG_DEBUG, "%d %d %d %d\n", ast->rate, ast->scale, ast->start, ast->sample_size);

             switch(tag1) {

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

                 codec_type = AVMEDIA_TYPE_VIDEO;

                 ast->sample_size = 0;
                 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)
                 st->duration = st->nb_frames;

             ast->frame_offset= ast->cum_len;

             avio_skip(pb, size - 12 * 4);

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

             if (!size)
                 break;

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

                 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];
                 switch(codec_type) {

                 case AVMEDIA_TYPE_VIDEO:

                     if(amv_file_format){
                         st->codec->width=avih_width;
                         st->codec->height=avih_height;

                         st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

                         st->codec->codec_id = CODEC_ID_AMV;

                         avio_skip(pb, size);

                         break;
                     }

                     tag1 = ff_get_bmp_header(pb, st);

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

                         st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

                         st->codec->codec_tag = tag1;
                         st->codec->codec_id = CODEC_ID_XSUB;
                         break;
                     }
 

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

                         st->codec->extradata_size= size - 10*4;
                         st->codec->extradata= av_malloc(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

                         if (!st->codec->extradata) {
                             st->codec->extradata_size= 0;
                             return AVERROR(ENOMEM);
                         }

                         avio_read(pb, st->codec->extradata, st->codec->extradata_size);

                     }

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

                         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->codec->extradata_size && (st->codec->bits_per_coded_sample <= 8)) {

                         int pal_size = (1 << st->codec->bits_per_coded_sample) << 2;
                         const uint8_t *pal_src;
 
                         pal_size = FFMIN(pal_size, st->codec->extradata_size);
                         pal_src = st->codec->extradata + st->codec->extradata_size - pal_size;
                         for (i = 0; i < pal_size/4; i++)

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

                         ast->has_pal = 1;

                     }
 

                     print_tag("video", tag1, 0);

                     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

                     st->codec->codec_tag = tag1;

                     st->codec->codec_id = ff_codec_get_id(ff_codec_bmp_tags, tag1);

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

                     // Support "Resolution 1:1" for Avid AVI Codec
                     if(tag1 == MKTAG('A', 'V', 'R', 'n') &&
                        st->codec->extradata_size >= 31 &&
                        !memcmp(&st->codec->extradata[28], "1:1", 3))
                         st->codec->codec_id = CODEC_ID_RAWVIDEO;

 
                     if(st->codec->codec_tag==0 && st->codec->height > 0 && st->codec->extradata_size < 1U<<30){
                         st->codec->extradata_size+= 9;

                         st->codec->extradata= av_realloc_f(st->codec->extradata, 1, st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

                         if(st->codec->extradata)
                             memcpy(st->codec->extradata + st->codec->extradata_size - 9, "BottomUp", 9);
                     }
                     st->codec->height= FFABS(st->codec->height);
 

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

                     break;

                 case AVMEDIA_TYPE_AUDIO:

                     ret = ff_get_wav_header(pb, st->codec, size);
                     if (ret < 0)
                         return ret;

                     ast->dshow_block_align= st->codec->block_align;

                     if(ast->sample_size && st->codec->block_align && ast->sample_size != st->codec->block_align){

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

                         ast->sample_size= st->codec->block_align;
                     }

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

                         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->codec->codec_id == CODEC_ID_AAC && st->codec->extradata_size)

                         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 (st->codec->stream_codec_tag == AV_RL32("Axan")){

                         st->codec->codec_id  = CODEC_ID_XAN_DPCM;
                         st->codec->codec_tag = 0;

                         ast->dshow_block_align = 0;

                     }

                     if (amv_file_format){

                         st->codec->codec_id  = CODEC_ID_ADPCM_IMA_AMV;

                         ast->dshow_block_align = 0;
                     }

                     break;

                 case AVMEDIA_TYPE_SUBTITLE:
                     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

                     st->request_probe= 1;

                     break;

                 default:

                     st->codec->codec_type = AVMEDIA_TYPE_DATA;

                     st->codec->codec_id= CODEC_ID_NONE;
                     st->codec->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]->codec->extradata_size
                 || s->streams[stream_index]->codec->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)){
                     st->codec->extradata_size= size;
                     st->codec->extradata= av_malloc(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
                     if (!st->codec->extradata) {
                         st->codec->extradata_size= 0;
                         return AVERROR(ENOMEM);
                     }
                     avio_read(pb, st->codec->extradata, st->codec->extradata_size);
                 }
 
                 if(st->codec->extradata_size & 1) //FIXME check if the encoder really did this correctly
                     avio_r8(pb);
             }
             break;

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

             i= avio_tell(pb);

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

                read_braindead_odml_indx(s, 0) < 0 && s->error_recognition >= FF_ER_EXPLODE)

                 goto fail;

             avio_seek(pb, i+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_ERROR, "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){

                 avi_read_tag(s, s->streams[s->nb_streams-1], tag, size);

                 break;
             }

         default:

             if(size > 1000000){

                 av_log(s, AV_LOG_ERROR, "Something went wrong during header parsing, "
                                         "I will ignore it and try to continue anyway.\n");

                 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;
             }

             /* 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 -1;
     }

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

         avi_load_index(s);

     avi->index_loaded |= 1;

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

     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(AVStream *st, AVPacket *pkt) {
     if (!strcmp(pkt->data, "GAB2") && AV_RL16(pkt->data+5) == 2) {

         uint8_t desc[256];
         int score = AVPROBE_SCORE_MAX / 2, ret;

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

         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 */

         pd = (AVProbeData) { .buf = pb->buf_ptr, .buf_size = pb->buf_end - pb->buf_ptr };

         if (!(sub_demuxer = av_probe_input_format2(&pd, 1, &score)))

             goto error;

         if (!(ast->sub_ctx = avformat_alloc_context()))
             goto error;
 
         ast->sub_ctx->pb      = pb;
         if (!avformat_open_input(&ast->sub_ctx, "", sub_demuxer, NULL)) {

             av_read_packet(ast->sub_ctx, &ast->sub_pkt);
             *st->codec = *ast->sub_ctx->streams[0]->codec;
             ast->sub_ctx->streams[0]->codec->extradata = NULL;
             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(&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 (av_read_packet(ast->sub_ctx, &ast->sub_pkt) < 0)
             ast->sub_pkt.data = NULL;
     }
     return sub_st;
 }
 

 static int get_stream_idx(int *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
     }
 }
 

 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); !url_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);
 //av_log(s, AV_LOG_DEBUG, "%X %X %X %X %X %X %X %X %"PRId64" %d %d\n", d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7], i, size, n);

         if(i + (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')){
             avio_skip(pb, size);
 //av_log(s, AV_LOG_DEBUG, "SKIP\n");
             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;
         }
 
         //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, "Skiping 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 ->codec->codec_type == AVMEDIA_TYPE_VIDEO
                    && st1->codec->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(   (st->discard >= AVDISCARD_DEFAULT && size==0)
                /*|| (st->discard >= AVDISCARD_NONKEY && !(pkt->flags & AV_PKT_FLAG_KEY))*/ //FIXME needs a little reordering
                || st->discard >= AVDISCARD_ALL){

                 if (!exit_early) {
                     ast->frame_offset += get_duration(ast, size);

                     avio_skip(pb, size);
                     goto start_sync;

                 }

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

                     ast->pal[k] = 0xFF<<24 | avio_rb32(pb)>>8;// b + (g << 8) + (r << 16);

                 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;

 //av_log(s, AV_LOG_DEBUG, "OK\n");
                 if(d[2]*256+d[3] == ast->prefix)
                     ast->prefix_count++;
                 else{
                     ast->prefix= d[2]*256+d[3];
                     ast->prefix_count= 0;
                 }
 
                 avi->stream_index= n;
                 ast->packet_size= size + 8;
                 ast->remaining= size;
 
                 if(size || !ast->sample_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 avi_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     AVIContext *avi = s->priv_data;
     AVIOContext *pb = s->pb;
     int err;

     void* dstr;

     if (CONFIG_DV_DEMUXER && avi->dv_demux) {

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

         if (size >= 0)
             return size;

     }

     if(avi->non_interleaved){

         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_DEBUG, "%"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;

         }

 //        av_log(s, AV_LOG_DEBUG, "%d\n", i);

         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_log(s, AV_LOG_DEBUG, "pos=%"PRId64"\n", pos);

             assert(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;

     }

 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;
 

         if(ast->sample_size <= 1) // minorityreport.AVI block_align=1024 sample_size=1 IMA-ADPCM

             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;

         if(ast->has_pal && pkt->data && 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) {

             dstr = pkt->destruct;

             size = avpriv_dv_produce_packet(avi->dv_demux, pkt,

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

             pkt->destruct = dstr;

             pkt->flags |= AV_PKT_FLAG_KEY;

             if (size < 0)
                 av_free_packet(pkt);

         } else if (st->codec->codec_type == AVMEDIA_TYPE_SUBTITLE
                    && !st->codec->codec_tag && read_gab2_sub(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;

 //av_log(s, AV_LOG_DEBUG, "dts:%"PRId64" offset:%"PRId64" %d/%d smpl_siz:%d base:%d st:%d size:%d\n", pkt->dts, ast->frame_offset, ast->scale, ast->rate, ast->sample_size, AV_TIME_BASE, avi->stream_index, size);

             pkt->stream_index = avi->stream_index;
 

             if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {

                 AVIndexEntry *e;
                 int index;

                 assert(st->index_entries);

                 index= av_index_search_timestamp(st, ast->frame_offset, 0);

                 e= &st->index_entries[index];

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

                     if (index == st->nb_index_entries-1){
                         int key=1;
                         int i;
                         uint32_t state=-1;
                         for(i=0; i<FFMIN(size,256); i++){
                             if(st->codec->codec_id == CODEC_ID_MPEG4){
                                 if(state == 0x1B6){
                                     key= !(pkt->data[i]&0xC0);
                                     break;
                                 }
                             }else
                                 break;
                             state= (state<<8) + pkt->data[i];
                         }
                         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_free_packet(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;

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

     unsigned last_pos= -1;

     int64_t idx1_pos, first_packet_pos = 0, data_offset = 0;

     nb_index_entries = size / 16;
     if (nb_index_entries <= 0)
         return -1;
 

     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]->codec->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(url_feof(pb))
             return -1;
 

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

         av_dlog(s, "%d: tag=0x%x flags=0x%x pos=0x%x 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;

         if(first_packet && first_packet_pos && len) {
             data_offset = first_packet_pos - pos;
             first_packet = 0;
         }
         pos += data_offset;
 

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

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

         else if(len || !ast->sample_size)

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

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

         last_pos= pos;

     }
     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;

             avio_seek(s->pb, pos + 4, SEEK_SET);

             size= avio_rl32(s->pb);

             if(pos + size > st->index_entries[1].pos)
                 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);

     return last_start > first_end;
 }
 

 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);

     int ret = -1;

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

         goto the_end; // maybe truncated file

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

     for(;;) {
         if (url_feof(pb))
             break;

         tag = avio_rl32(pb);
         size = avio_rl32(pb);

         av_dlog(s, "tag=%c%c%c%c size=0x%x\n",
                  tag        & 0xff,
                 (tag >>  8) & 0xff,
                 (tag >> 16) & 0xff,
                 (tag >> 24) & 0xff,
                 size);

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

             avi->index_loaded=2;

             ret = 0;

             break;
         }

 
         size += (size & 1);
         if (avio_skip(pb, size) < 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_free_packet(&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)
         av_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;

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

         avi->index_loaded |= 1;

     }

     assert(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)

         return -1;

     /* 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_DEBUG, "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.                     */
         assert(stream_index == 0);
 

         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.        */

         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;

 //        assert(st2->codec->block_align);

         assert((int64_t)st2->time_base.num*ast2->rate == (int64_t)st2->time_base.den*ast2->scale);

         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->codec->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->codec->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)
         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_free(ast->sub_buffer);
             av_free_packet(&ast->sub_pkt);

         }

     }
 

     av_free(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(!memcmp(p->buf  , avi_headers[i]  , 4) &&
            !memcmp(p->buf+8, avi_headers[i]+4, 4))
             return AVPROBE_SCORE_MAX;
 
     return 0;

 }
 

 AVInputFormat ff_avi_demuxer = {

     .name           = "avi",
     .long_name      = NULL_IF_CONFIG_SMALL("AVI format"),
     .priv_data_size = sizeof(AVIContext),
     .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,

 };