/*
  * "NUT" Container Format demuxer
  * Copyright (c) 2004-2006 Michael Niedermayer
  * Copyright (c) 2003 Alex Beregszaszi
  *
  * 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/avstring.h"

 #include "libavutil/avassert.h"

 #include "libavutil/bswap.h"

 #include "libavutil/dict.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/tree.h"

 #include "avio_internal.h"

 #include "nut.h"
 

 #define NUT_MAX_STREAMS 256    /* arbitrary sanity check value */
 

 static int get_str(AVIOContext *bc, char *string, unsigned int maxlen)
 {
     unsigned int len = ffio_read_varlen(bc);

     if (len && maxlen)

         avio_read(bc, string, FFMIN(len, maxlen));

     while (len > maxlen) {

         avio_r8(bc);

         len--;
     }
 

     if (maxlen)
         string[FFMIN(len, maxlen - 1)] = 0;

     if (maxlen == len)

         return -1;
     else
         return 0;
 }
 

 static int64_t get_s(AVIOContext *bc)
 {

     int64_t v = ffio_read_varlen(bc) + 1;

     if (v & 1)
         return -(v >> 1);
     else
         return  (v >> 1);

 }
 

 static uint64_t get_fourcc(AVIOContext *bc)
 {
     unsigned int len = ffio_read_varlen(bc);

     if (len == 2)
         return avio_rl16(bc);
     else if (len == 4)
         return avio_rl32(bc);
     else
         return -1;

 }
 
 #ifdef TRACE

 static inline uint64_t get_v_trace(AVIOContext *bc, char *file,
                                    char *func, int line)
 {
     uint64_t v = ffio_read_varlen(bc);

     av_log(NULL, AV_LOG_DEBUG, "get_v %5"PRId64" / %"PRIX64" in %s %s:%d\n",
            v, v, file, func, line);

     return v;
 }
 

 static inline int64_t get_s_trace(AVIOContext *bc, char *file,
                                   char *func, int line)
 {
     int64_t v = get_s(bc);

     av_log(NULL, AV_LOG_DEBUG, "get_s %5"PRId64" / %"PRIX64" in %s %s:%d\n",
            v, v, file, func, line);

     return v;
 }
 

 static inline uint64_t get_vb_trace(AVIOContext *bc, char *file,
                                     char *func, int line)
 {
     uint64_t v = get_vb(bc);

     av_log(NULL, AV_LOG_DEBUG, "get_vb %5"PRId64" / %"PRIX64" in %s %s:%d\n",
            v, v, file, func, line);

     return v;
 }

 #define ffio_read_varlen(bc) get_v_trace(bc,  __FILE__, __PRETTY_FUNCTION__, __LINE__)
 #define get_s(bc)            get_s_trace(bc,  __FILE__, __PRETTY_FUNCTION__, __LINE__)
 #define get_vb(bc)           get_vb_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)

 #endif
 

 static int get_packetheader(NUTContext *nut, AVIOContext *bc,
                             int calculate_checksum, uint64_t startcode)

 {

     int64_t size;

 //    start = avio_tell(bc) - 8;

     startcode = av_be2ne64(startcode);
     startcode = ff_crc04C11DB7_update(0, (uint8_t*) &startcode, 8);

     ffio_init_checksum(bc, ff_crc04C11DB7_update, startcode);

     size = ffio_read_varlen(bc);
     if (size > 4096)

         avio_rb32(bc);

     if (ffio_get_checksum(bc) && size > 4096)

         return -1;

     ffio_init_checksum(bc, calculate_checksum ? ff_crc04C11DB7_update : NULL, 0);

 
     return size;
 }
 

 static uint64_t find_any_startcode(AVIOContext *bc, int64_t pos)
 {
     uint64_t state = 0;
 
     if (pos >= 0)
         /* Note, this may fail if the stream is not seekable, but that should
          * not matter, as in this case we simply start where we currently are */
         avio_seek(bc, pos, SEEK_SET);

     while (!url_feof(bc)) {

         state = (state << 8) | avio_r8(bc);
         if ((state >> 56) != 'N')

             continue;

         switch (state) {

         case MAIN_STARTCODE:
         case STREAM_STARTCODE:
         case SYNCPOINT_STARTCODE:
         case INFO_STARTCODE:
         case INDEX_STARTCODE:
             return state;
         }
     }
 
     return 0;
 }
 
 /**

  * Find the given startcode.

  * @param code the startcode
  * @param pos the start position of the search, or -1 if the current position

  * @return the position of the startcode or -1 if not found

  */

 static int64_t find_startcode(AVIOContext *bc, uint64_t code, int64_t pos)
 {
     for (;;) {
         uint64_t startcode = find_any_startcode(bc, pos);
         if (startcode == code)

             return avio_tell(bc) - 8;

         else if (startcode == 0)

             return -1;

         pos = -1;

     }
 }
 

 static int nut_probe(AVProbeData *p)
 {

     int i;

     uint64_t code = 0;

 
     for (i = 0; i < p->buf_size; i++) {
         code = (code << 8) | p->buf[i];
         if (code == MAIN_STARTCODE)
             return AVPROBE_SCORE_MAX;
     }
     return 0;
 }
 

 #define GET_V(dst, check)                                                 \
     tmp = ffio_read_varlen(bc);                                           \
     if (!(check)) {                                                       \
         av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);  \
         return -1;                                                        \
     }                                                                     \
     dst = tmp;

 static int skip_reserved(AVIOContext *bc, int64_t pos)
 {

     pos -= avio_tell(bc);

     if (pos < 0) {

         avio_seek(bc, pos, SEEK_CUR);

         return -1;

     } else {
         while (pos--)

             avio_r8(bc);

         return 0;
     }
 }
 

 static int decode_main_header(NUTContext *nut)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     uint64_t tmp, end;
     unsigned int stream_count;

     int i, j, count;
     int tmp_stream, tmp_mul, tmp_pts, tmp_size, tmp_res, tmp_head_idx;

     end  = get_packetheader(nut, bc, 1, MAIN_STARTCODE);

     end += avio_tell(bc);

     GET_V(tmp, tmp >= 2 && tmp <= 3)
     GET_V(stream_count, tmp > 0 && tmp <= NUT_MAX_STREAMS)

     nut->max_distance = ffio_read_varlen(bc);

     if (nut->max_distance > 65536) {

         av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);

         nut->max_distance = 65536;

     }
 

     GET_V(nut->time_base_count, tmp > 0 && tmp < INT_MAX / sizeof(AVRational))
     nut->time_base = av_malloc(nut->time_base_count * sizeof(AVRational));

     for (i = 0; i < nut->time_base_count; i++) {
         GET_V(nut->time_base[i].num, tmp > 0 && tmp < (1ULL << 31))
         GET_V(nut->time_base[i].den, tmp > 0 && tmp < (1ULL << 31))
         if (av_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1) {

             av_log(s, AV_LOG_ERROR, "time base invalid\n");

             return AVERROR_INVALIDDATA;

         }
     }

     tmp_pts      = 0;
     tmp_mul      = 1;
     tmp_stream   = 0;
     tmp_head_idx = 0;
     for (i = 0; i < 256;) {
         int tmp_flags  = ffio_read_varlen(bc);
         int tmp_fields = ffio_read_varlen(bc);
 
         if (tmp_fields > 0)
             tmp_pts = get_s(bc);
         if (tmp_fields > 1)
             tmp_mul = ffio_read_varlen(bc);
         if (tmp_fields > 2)
             tmp_stream = ffio_read_varlen(bc);
         if (tmp_fields > 3)
             tmp_size = ffio_read_varlen(bc);
         else
             tmp_size = 0;
         if (tmp_fields > 4)
             tmp_res = ffio_read_varlen(bc);
         else
             tmp_res = 0;
         if (tmp_fields > 5)
             count = ffio_read_varlen(bc);
         else
             count = tmp_mul - tmp_size;
         if (tmp_fields > 6)
             get_s(bc);
         if (tmp_fields > 7)
             tmp_head_idx = ffio_read_varlen(bc);
 
         while (tmp_fields-- > 8)
             ffio_read_varlen(bc);
 
         if (count == 0 || i + count > 256) {

             av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);

             return AVERROR_INVALIDDATA;

         }

         if (tmp_stream >= stream_count) {

             av_log(s, AV_LOG_ERROR, "illegal stream number\n");

             return AVERROR_INVALIDDATA;

         }
 

         for (j = 0; j < count; j++, i++) {

             if (i == 'N') {

                 nut->frame_code[i].flags = FLAG_INVALID;

                 j--;
                 continue;
             }

             nut->frame_code[i].flags          = tmp_flags;
             nut->frame_code[i].pts_delta      = tmp_pts;
             nut->frame_code[i].stream_id      = tmp_stream;
             nut->frame_code[i].size_mul       = tmp_mul;
             nut->frame_code[i].size_lsb       = tmp_size + j;
             nut->frame_code[i].reserved_count = tmp_res;
             nut->frame_code[i].header_idx     = tmp_head_idx;

         }
     }

     av_assert0(nut->frame_code['N'].flags == FLAG_INVALID);

     if (end > avio_tell(bc) + 4) {
         int rem = 1024;
         GET_V(nut->header_count, tmp < 128U)

         nut->header_count++;

         for (i = 1; i < nut->header_count; i++) {

             uint8_t *hdr;

             GET_V(nut->header_len[i], tmp > 0 && tmp < 256);

             rem -= nut->header_len[i];

             if (rem < 0) {

                 av_log(s, AV_LOG_ERROR, "invalid elision header\n");

                 return AVERROR_INVALIDDATA;

             }

             hdr = av_malloc(nut->header_len[i]);
             if (!hdr)
                 return AVERROR(ENOMEM);
             avio_read(bc, hdr, nut->header_len[i]);
             nut->header[i] = hdr;

         }

         av_assert0(nut->header_len[0] == 0);

     }
 

     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {

         av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");

         return AVERROR_INVALIDDATA;

     }
 

     nut->stream = av_mallocz(sizeof(StreamContext) * stream_count);
     for (i = 0; i < stream_count; i++)

         avformat_new_stream(s, NULL);

 
     return 0;
 }
 

 static int decode_stream_header(NUTContext *nut)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     StreamContext *stc;

     int class, stream_id;

     uint64_t tmp, end;
     AVStream *st;
 

     end  = get_packetheader(nut, bc, 1, STREAM_STARTCODE);

     end += avio_tell(bc);

     GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);

     stc = &nut->stream[stream_id];
     st  = s->streams[stream_id];

     if (!st)

         return AVERROR(ENOMEM);

     class                = ffio_read_varlen(bc);
     tmp                  = get_fourcc(bc);
     st->codec->codec_tag = tmp;
     switch (class) {
     case 0:
         st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
         st->codec->codec_id   = av_codec_get_id((const AVCodecTag * const []) {
                                                     ff_codec_bmp_tags,
                                                     ff_nut_video_tags,
                                                     0
                                                 },
                                                 tmp);
         break;
     case 1:
         st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
         st->codec->codec_id   = ff_codec_get_id(ff_codec_wav_tags, tmp);
         break;
     case 2:
         st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
         st->codec->codec_id   = ff_codec_get_id(ff_nut_subtitle_tags, tmp);
         break;
     case 3:
         st->codec->codec_type = AVMEDIA_TYPE_DATA;
         break;
     default:
         av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
         return -1;

     }

     if (class < 3 && st->codec->codec_id == CODEC_ID_NONE)
         av_log(s, AV_LOG_ERROR,
                "Unknown codec tag '0x%04x' for stream number %d\n",
                (unsigned int) tmp, stream_id);
 
     GET_V(stc->time_base_id, tmp < nut->time_base_count);
     GET_V(stc->msb_pts_shift, tmp < 16);
     stc->max_pts_distance = ffio_read_varlen(bc);
     GET_V(stc->decode_delay, tmp < 1000); // sanity limit, raise this if Moore's law is true
     st->codec->has_b_frames = stc->decode_delay;
     ffio_read_varlen(bc); // stream flags
 
     GET_V(st->codec->extradata_size, tmp < (1 << 30));
     if (st->codec->extradata_size) {
         st->codec->extradata = av_mallocz(st->codec->extradata_size +
                                           FF_INPUT_BUFFER_PADDING_SIZE);

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

     }
 

     if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
         GET_V(st->codec->width,  tmp > 0)

         GET_V(st->codec->height, tmp > 0)

         st->sample_aspect_ratio.num = ffio_read_varlen(bc);
         st->sample_aspect_ratio.den = ffio_read_varlen(bc);
         if ((!st->sample_aspect_ratio.num) != (!st->sample_aspect_ratio.den)) {
             av_log(s, AV_LOG_ERROR, "invalid aspect ratio %d/%d\n",
                    st->sample_aspect_ratio.num, st->sample_aspect_ratio.den);

             return -1;
         }

         ffio_read_varlen(bc); /* csp type */

     } else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
         GET_V(st->codec->sample_rate, tmp > 0)

         ffio_read_varlen(bc); // samplerate_den

         GET_V(st->codec->channels, tmp > 0)
     }

     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
         av_log(s, AV_LOG_ERROR,
                "stream header %d checksum mismatch\n", stream_id);

         return -1;
     }

     stc->time_base = &nut->time_base[stc->time_base_id];
     avpriv_set_pts_info(s->streams[stream_id], 63, stc->time_base->num,
                         stc->time_base->den);

     return 0;
 }
 

 static void set_disposition_bits(AVFormatContext *avf, char *value,
                                  int stream_id)
 {

     int flag = 0, i;

 
     for (i = 0; ff_nut_dispositions[i].flag; ++i)

         if (!strcmp(ff_nut_dispositions[i].str, value))
             flag = ff_nut_dispositions[i].flag;
     if (!flag)
         av_log(avf, AV_LOG_INFO, "unknown disposition type '%s'\n", value);
     for (i = 0; i < avf->nb_streams; ++i)
         if (stream_id == i || stream_id == -1)
             avf->streams[i]->disposition |= flag;
 }
 

 static int decode_info_header(NUTContext *nut)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     uint64_t tmp, chapter_start, chapter_len;
     unsigned int stream_id_plus1, count;

     int chapter_id, i;
     int64_t value, end;

     char name[256], str_value[1024], type_str[256];

     const char *type;

     AVChapter *chapter      = NULL;
     AVStream *st            = NULL;

     AVDictionary **metadata = NULL;

     end  = get_packetheader(nut, bc, 1, INFO_STARTCODE);

     end += avio_tell(bc);

 
     GET_V(stream_id_plus1, tmp <= s->nb_streams)

     chapter_id    = get_s(bc);
     chapter_start = ffio_read_varlen(bc);
     chapter_len   = ffio_read_varlen(bc);
     count         = ffio_read_varlen(bc);
 
     if (chapter_id && !stream_id_plus1) {
         int64_t start = chapter_start / nut->time_base_count;
         chapter = avpriv_new_chapter(s, chapter_id,
                                      nut->time_base[chapter_start %
                                                     nut->time_base_count],
                                      start, start + chapter_len, NULL);

         metadata = &chapter->metadata;

     } else if (stream_id_plus1) {
         st       = s->streams[stream_id_plus1 - 1];

         metadata = &st->metadata;
     } else
         metadata = &s->metadata;

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

         get_str(bc, name, sizeof(name));

         value = get_s(bc);
         if (value == -1) {
             type = "UTF-8";

             get_str(bc, str_value, sizeof(str_value));

         } else if (value == -2) {

             get_str(bc, type_str, sizeof(type_str));

             type = type_str;

             get_str(bc, str_value, sizeof(str_value));

         } else if (value == -3) {
             type  = "s";
             value = get_s(bc);
         } else if (value == -4) {
             type  = "t";
             value = ffio_read_varlen(bc);
         } else if (value < -4) {
             type = "r";

             get_s(bc);

         } else {
             type = "v";

         }
 

         if (stream_id_plus1 > s->nb_streams) {

             av_log(s, AV_LOG_ERROR, "invalid stream id for info packet\n");
             continue;
         }
 

         if (!strcmp(type, "UTF-8")) {
             if (chapter_id == 0 && !strcmp(name, "Disposition")) {

                 set_disposition_bits(s, str_value, stream_id_plus1 - 1);

                 continue;
             }

             if (metadata && av_strcasecmp(name, "Uses") &&
                 av_strcasecmp(name, "Depends") && av_strcasecmp(name, "Replaces"))

                 av_dict_set(metadata, name, str_value, 0);

         }

     }
 

     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {

         av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");

         return -1;
     }
     return 0;
 }
 

 static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     int64_t end, tmp;

     nut->last_syncpoint_pos = avio_tell(bc) - 8;

     end  = get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);

     end += avio_tell(bc);

     tmp       = ffio_read_varlen(bc);
     *back_ptr = nut->last_syncpoint_pos - 16 * ffio_read_varlen(bc);
     if (*back_ptr < 0)

         return -1;

     ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count],
                     tmp / nut->time_base_count);

     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {

         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");

         return -1;
     }

     *ts = tmp / s->nb_streams *
           av_q2d(nut->time_base[tmp % s->nb_streams]) * AV_TIME_BASE;

     ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);

     return 0;
 }
 

 static int find_and_decode_index(NUTContext *nut)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     uint64_t tmp, end;
     int i, j, syncpoint_count;

     int64_t filesize = avio_size(bc);

     int64_t *syncpoints;
     int8_t *has_keyframe;

     int ret = -1;

     avio_seek(bc, filesize - 12, SEEK_SET);
     avio_seek(bc, filesize - avio_rb64(bc), SEEK_SET);
     if (avio_rb64(bc) != INDEX_STARTCODE) {

         av_log(s, AV_LOG_ERROR, "no index at the end\n");
         return -1;
     }
 

     end  = get_packetheader(nut, bc, 1, INDEX_STARTCODE);

     end += avio_tell(bc);

     ffio_read_varlen(bc); // max_pts
     GET_V(syncpoint_count, tmp < INT_MAX / 8 && tmp > 0)
     syncpoints   = av_malloc(sizeof(int64_t) *  syncpoint_count);
     has_keyframe = av_malloc(sizeof(int8_t)  * (syncpoint_count + 1));
     for (i = 0; i < syncpoint_count; i++) {

         syncpoints[i] = ffio_read_varlen(bc);

         if (syncpoints[i] <= 0)

             goto fail;

         if (i)
             syncpoints[i] += syncpoints[i - 1];
     }
 
     for (i = 0; i < s->nb_streams; i++) {
         int64_t last_pts = -1;
         for (j = 0; j < syncpoint_count;) {
             uint64_t x = ffio_read_varlen(bc);
             int type   = x & 1;
             int n      = j;
             x >>= 1;
             if (type) {
                 int flag = x & 1;
                 x >>= 1;
                 if (n + x >= syncpoint_count + 1) {

                     av_log(s, AV_LOG_ERROR, "index overflow A\n");

                     goto fail;

                 }

                 while (x--)
                     has_keyframe[n++] = flag;
                 has_keyframe[n++] = !flag;
             } else {
                 while (x != 1) {
                     if (n >= syncpoint_count + 1) {

                         av_log(s, AV_LOG_ERROR, "index overflow B\n");

                         goto fail;

                     }

                     has_keyframe[n++] = x & 1;
                     x >>= 1;

                 }
             }

             if (has_keyframe[0]) {

                 av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");

                 goto fail;

             }

             av_assert0(n <= syncpoint_count + 1);

             for (; j < n && j < syncpoint_count; j++) {
                 if (has_keyframe[j]) {
                     uint64_t B, A = ffio_read_varlen(bc);
                     if (!A) {
                         A = ffio_read_varlen(bc);
                         B = ffio_read_varlen(bc);
                         // eor_pts[j][i] = last_pts + A + B
                     } else
                         B = 0;
                     av_add_index_entry(s->streams[i], 16 * syncpoints[j - 1],
                                        last_pts + A, 0, 0, AVINDEX_KEYFRAME);

                     last_pts += A + B;
                 }
             }
         }
     }
 

     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {

         av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");

         goto fail;

     }

     ret = 0;
 

 fail:
     av_free(syncpoints);
     av_free(has_keyframe);
     return ret;

 }
 

 static int nut_read_header(AVFormatContext *s)

 {
     NUTContext *nut = s->priv_data;

     AVIOContext *bc = s->pb;

     int64_t pos;

     int initialized_stream_count;

     nut->avf = s;

 
     /* main header */

     pos = 0;
     do {
         pos = find_startcode(bc, MAIN_STARTCODE, pos) + 1;
         if (pos < 0 + 1) {

             av_log(s, AV_LOG_ERROR, "No main startcode found.\n");

             return AVERROR_INVALIDDATA;

         }

     } while (decode_main_header(nut) < 0);

 
     /* stream headers */

     pos = 0;
     for (initialized_stream_count = 0; initialized_stream_count < s->nb_streams;) {
         pos = find_startcode(bc, STREAM_STARTCODE, pos) + 1;
         if (pos < 0 + 1) {

             av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");

             return AVERROR_INVALIDDATA;

         }

         if (decode_stream_header(nut) >= 0)

             initialized_stream_count++;

     }
 
     /* info headers */

     pos = 0;
     for (;;) {
         uint64_t startcode = find_any_startcode(bc, pos);
         pos = avio_tell(bc);

         if (startcode == 0) {

             av_log(s, AV_LOG_ERROR, "EOF before video frames\n");

             return AVERROR_INVALIDDATA;

         } else if (startcode == SYNCPOINT_STARTCODE) {
             nut->next_startcode = startcode;

             break;

         } else if (startcode != INFO_STARTCODE) {

             continue;
         }
 
         decode_info_header(nut);
     }
 

     s->data_offset = pos - 8;

     if (bc->seekable) {
         int64_t orig_pos = avio_tell(bc);

         find_and_decode_index(nut);

         avio_seek(bc, orig_pos, SEEK_SET);

     }

     av_assert0(nut->next_startcode == SYNCPOINT_STARTCODE);

     ff_metadata_conv_ctx(s, NULL, ff_nut_metadata_conv);
 

     return 0;
 }
 

 static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id,
                                uint8_t *header_idx, int frame_code)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     StreamContext *stc;
     int size, flags, size_mul, pts_delta, i, reserved_count;
     uint64_t tmp;
 

     if (avio_tell(bc) > nut->last_syncpoint_pos + nut->max_distance) {
         av_log(s, AV_LOG_ERROR,
                "Last frame must have been damaged %"PRId64" > %"PRId64" + %d\n",
                avio_tell(bc), nut->last_syncpoint_pos, nut->max_distance);

         return AVERROR_INVALIDDATA;

     }
 
     flags          = nut->frame_code[frame_code].flags;
     size_mul       = nut->frame_code[frame_code].size_mul;
     size           = nut->frame_code[frame_code].size_lsb;
     *stream_id     = nut->frame_code[frame_code].stream_id;
     pts_delta      = nut->frame_code[frame_code].pts_delta;
     reserved_count = nut->frame_code[frame_code].reserved_count;

     *header_idx    = nut->frame_code[frame_code].header_idx;

     if (flags & FLAG_INVALID)

         return AVERROR_INVALIDDATA;

     if (flags & FLAG_CODED)

         flags ^= ffio_read_varlen(bc);

     if (flags & FLAG_STREAM_ID) {

         GET_V(*stream_id, tmp < s->nb_streams)
     }

     stc = &nut->stream[*stream_id];
     if (flags & FLAG_CODED_PTS) {
         int coded_pts = ffio_read_varlen(bc);
         // FIXME check last_pts validity?
         if (coded_pts < (1 << stc->msb_pts_shift)) {
             *pts = ff_lsb2full(stc, coded_pts);
         } else
             *pts = coded_pts - (1 << stc->msb_pts_shift);
     } else
         *pts = stc->last_pts + pts_delta;
     if (flags & FLAG_SIZE_MSB)
         size += size_mul * ffio_read_varlen(bc);
     if (flags & FLAG_MATCH_TIME)

         get_s(bc);

     if (flags & FLAG_HEADER_IDX)
         *header_idx = ffio_read_varlen(bc);
     if (flags & FLAG_RESERVED)
         reserved_count = ffio_read_varlen(bc);
     for (i = 0; i < reserved_count; i++)

         ffio_read_varlen(bc);

     if (*header_idx >= (unsigned)nut->header_count) {

         av_log(s, AV_LOG_ERROR, "header_idx invalid\n");

         return AVERROR_INVALIDDATA;

     }

     if (size > 4096)
         *header_idx = 0;

     size -= nut->header_len[*header_idx];
 

     if (flags & FLAG_CHECKSUM) {
         avio_rb32(bc); // FIXME check this
     } else if (size > 2 * nut->max_distance || FFABS(stc->last_pts - *pts) >
                stc->max_pts_distance) {

         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");

         return AVERROR_INVALIDDATA;

     }
 

     stc->last_pts   = *pts;
     stc->last_flags = flags;

 
     return size;
 }
 

 static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code)
 {
     AVFormatContext *s = nut->avf;
     AVIOContext *bc    = s->pb;

     int size, stream_id, discard;

     int64_t pts, last_IP_pts;

     StreamContext *stc;

     uint8_t header_idx;

     size = decode_frame_header(nut, &pts, &stream_id, &header_idx, frame_code);
     if (size < 0)

         return size;

     stc = &nut->stream[stream_id];

 
     if (stc->last_flags & FLAG_KEY)

         stc->skip_until_key_frame = 0;
 
     discard     = s->streams[stream_id]->discard;
     last_IP_pts = s->streams[stream_id]->last_IP_pts;
     if ((discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY)) ||
         (discard >= AVDISCARD_BIDIR  && last_IP_pts != AV_NOPTS_VALUE &&
          last_IP_pts > pts) ||
         discard >= AVDISCARD_ALL ||
         stc->skip_until_key_frame) {

         avio_skip(bc, size);

         return 1;
     }
 

     av_new_packet(pkt, size + nut->header_len[header_idx]);
     memcpy(pkt->data, nut->header[header_idx], nut->header_len[header_idx]);

     pkt->pos = avio_tell(bc); // FIXME

     avio_read(bc, pkt->data + nut->header_len[header_idx], size);

     pkt->stream_index = stream_id;

     if (stc->last_flags & FLAG_KEY)

         pkt->flags |= AV_PKT_FLAG_KEY;

     pkt->pts = pts;
 
     return 0;
 }
 
 static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     NUTContext *nut = s->priv_data;

     AVIOContext *bc = s->pb;

     int i, frame_code = 0, ret, skip;

     int64_t ts, back_ptr;

     for (;;) {
         int64_t pos  = avio_tell(bc);
         uint64_t tmp = nut->next_startcode;
         nut->next_startcode = 0;

         if (tmp) {
             pos -= 8;
         } else {

             frame_code = avio_r8(bc);

             if (url_feof(bc))

                 return -1;

             if (frame_code == 'N') {
                 tmp = frame_code;
                 for (i = 1; i < 8; i++)
                     tmp = (tmp << 8) + avio_r8(bc);

             }
         }

         switch (tmp) {

         case MAIN_STARTCODE:
         case STREAM_STARTCODE:
         case INDEX_STARTCODE:

             skip = get_packetheader(nut, bc, 0, tmp);

             avio_skip(bc, skip);

             break;
         case INFO_STARTCODE:

             if (decode_info_header(nut) < 0)

                 goto resync;
             break;
         case SYNCPOINT_STARTCODE:

             if (decode_syncpoint(nut, &ts, &back_ptr) < 0)

                 goto resync;

             frame_code = avio_r8(bc);

         case 0:

             ret = decode_frame(nut, pkt, frame_code);
             if (ret == 0)

                 return 0;

             else if (ret == 1) // OK but discard packet

                 break;
         default:
 resync:

             av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
             tmp = find_any_startcode(bc, nut->last_syncpoint_pos + 1);
             if (tmp == 0)

                 return AVERROR_INVALIDDATA;

             av_log(s, AV_LOG_DEBUG, "sync\n");
             nut->next_startcode = tmp;

         }
     }
 }
 

 static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index,
                                   int64_t *pos_arg, int64_t pos_limit)
 {

     NUTContext *nut = s->priv_data;

     AVIOContext *bc = s->pb;

     int64_t pos, pts, back_ptr;

     av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n",
            stream_index, *pos_arg, pos_limit);

     pos = *pos_arg;
     do {
         pos = find_startcode(bc, SYNCPOINT_STARTCODE, pos) + 1;
         if (pos < 1) {

             av_assert0(nut->next_startcode == 0);

             av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");

             return AV_NOPTS_VALUE;
         }

     } while (decode_syncpoint(nut, &pts, &back_ptr) < 0);
     *pos_arg = pos - 1;

     av_assert0(nut->last_syncpoint_pos == *pos_arg);

     av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts, back_ptr);

     if (stream_index == -2)

         return back_ptr;

     av_assert0(stream_index == -1);
     return pts;

 }
 

 static int read_seek(AVFormatContext *s, int stream_index,
                      int64_t pts, int flags)
 {
     NUTContext *nut    = s->priv_data;
     AVStream *st       = s->streams[stream_index];
     Syncpoint dummy    = { .ts = pts * av_q2d(st->time_base) * AV_TIME_BASE };
     Syncpoint nopts_sp = { .ts = AV_NOPTS_VALUE, .back_ptr = AV_NOPTS_VALUE };
     Syncpoint *sp, *next_node[2] = { &nopts_sp, &nopts_sp };

     int64_t pos, pos2, ts;

     int i;

     if (st->index_entries) {
         int index = av_index_search_timestamp(st, pts, flags);
         if (index < 0)

             return -1;
 

         pos2 = st->index_entries[index].pos;
         ts   = st->index_entries[index].timestamp;
     } else {

         av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pts_cmp,
                      (void **) next_node);

         av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n",
                next_node[0]->pos, next_node[1]->pos, next_node[0]->ts,
                next_node[1]->ts);
         pos = ff_gen_search(s, -1, dummy.ts, next_node[0]->pos,
                             next_node[1]->pos, next_node[1]->pos,
                             next_node[0]->ts, next_node[1]->ts,
                             AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
 
         if (!(flags & AVSEEK_FLAG_BACKWARD)) {
             dummy.pos    = pos + 16;
             next_node[1] = &nopts_sp;

             av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,
                          (void **) next_node);

             pos2 = ff_gen_search(s, -2, dummy.pos, next_node[0]->pos,
                                  next_node[1]->pos, next_node[1]->pos,
                                  next_node[0]->back_ptr, next_node[1]->back_ptr,
                                  flags, &ts, nut_read_timestamp);
             if (pos2 >= 0)
                 pos = pos2;
             // FIXME dir but I think it does not matter

         }

         dummy.pos = pos;
         sp = av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,
                           NULL);

         av_assert0(sp);

         pos2 = sp->back_ptr - 15;

     }
     av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);

     pos = find_startcode(s->pb, SYNCPOINT_STARTCODE, pos2);

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

     av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);

     if (pos2 > pos || pos2 + 15 < pos)

         av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");

     for (i = 0; i < s->nb_streams; i++)
         nut->stream[i].skip_until_key_frame = 1;

     return 0;
 }
 

 static int nut_read_close(AVFormatContext *s)
 {
     NUTContext *nut = s->priv_data;

     int i;

 
     av_freep(&nut->time_base);
     av_freep(&nut->stream);

     ff_nut_free_sp(nut);

     for (i = 1; i < nut->header_count; i++)

         av_freep(&nut->header[i]);

 
     return 0;
 }
 

 AVInputFormat ff_nut_demuxer = {

     .name           = "nut",
     .long_name      = NULL_IF_CONFIG_SMALL("NUT format"),

     .flags          = AVFMT_SEEK_TO_PTS,

     .priv_data_size = sizeof(NUTContext),
     .read_probe     = nut_probe,
     .read_header    = nut_read_header,
     .read_packet    = nut_read_packet,
     .read_close     = nut_read_close,
     .read_seek      = read_seek,

     .extensions     = "nut",
     .codec_tag      = (const AVCodecTag * const []) {
         ff_codec_bmp_tags, ff_nut_video_tags, ff_codec_wav_tags,
         ff_nut_subtitle_tags, 0
     },

 };