/*

  * MPEG1/2 demuxer

  * Copyright (c) 2000, 2001, 2002 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 "avformat.h"

 #include "internal.h"

 #include "mpeg.h"

 #if CONFIG_VOBSUB_DEMUXER
 # include "subtitles.h"
 # include "libavutil/bprint.h"
 #endif
 

 #undef NDEBUG
 #include <assert.h>
 

 /*********************************************/
 /* demux code */
 
 #define MAX_SYNC_SIZE 100000
 

 static int check_pes(const uint8_t *p, const uint8_t *end){

     int pes1;
     int pes2=      (p[3] & 0xC0) == 0x80
                 && (p[4] & 0xC0) != 0x40
                 &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));
 
     for(p+=3; p<end && *p == 0xFF; p++);
     if((*p&0xC0) == 0x40) p+=2;
     if((*p&0xF0) == 0x20){
         pes1= p[0]&p[2]&p[4]&1;
     }else if((*p&0xF0) == 0x30){
         pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;
     }else
         pes1 = *p == 0x0F;
 
     return pes1||pes2;
 }
 

 static int check_pack_header(const uint8_t *buf) {
     return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;
 }
 

 static int mpegps_probe(AVProbeData *p)
 {

     uint32_t code= -1;

     int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;

     int i;

     int score=0;

     for(i=0; i<p->buf_size; i++){
         code = (code<<8) + p->buf[i];

         if ((code & 0xffffff00) == 0x100) {

             int len= p->buf[i+1] << 8 | p->buf[i+2];

             int pes= check_pes(p->buf+i, p->buf+p->buf_size);

             int pack = check_pack_header(p->buf+i);

             if(code == SYSTEM_HEADER_START_CODE) sys++;

             else if(code == PACK_START_CODE && pack) pspack++;

             else if((code & 0xf0) == VIDEO_ID &&  pes) vid++;

             // skip pes payload to avoid start code emulation for private
             // and audio streams
             else if((code & 0xe0) == AUDIO_ID &&  pes) {audio++; i+=len;}
             else if(code == PRIVATE_STREAM_1  &&  pes) {priv1++; i+=len;}

             else if(code == 0x1fd             &&  pes) vid++; //VC1

 
             else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
             else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;

             else if(code == PRIVATE_STREAM_1  && !pes) invalid++;

         }

     }

     if(vid+audio > invalid+1)     /* invalid VDR files nd short PES streams */

         score= AVPROBE_SCORE_MAX/4;
 

     if(sys>invalid && sys*9 <= pspack*10)

         return (audio > 12 || vid > 3 || pspack > 2) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4+1; // +1 for .mpg

     if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)

         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
     if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */

         return (audio > 12 || vid > 3 + 2*invalid) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;

 
     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1

     //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6

     //Have\ Yourself\ a\ Merry\ Little\ Christmas.mp3 0 0 0 5 0 1 len:21618

     return score;

 }
 
 

 typedef struct MpegDemuxContext {

     int32_t header_state;

     unsigned char psm_es_type[256];

     int sofdec;

 #if CONFIG_VOBSUB_DEMUXER
     AVFormatContext *sub_ctx;
     FFDemuxSubtitlesQueue q;
 #endif

 } MpegDemuxContext;
 

 static int mpegps_read_header(AVFormatContext *s)

 {
     MpegDemuxContext *m = s->priv_data;

     const char *sofdec = "Sofdec";
     int v, i = 0;

     int64_t last_pos = avio_tell(s->pb);

     m->header_state = 0xff;
     s->ctx_flags |= AVFMTCTX_NOHEADER;
 

     m->sofdec = -1;
     do {

         v = avio_r8(s->pb);

         m->sofdec++;
     } while (v == sofdec[i] && i++ < 6);

     m->sofdec = (m->sofdec == 6) ? 1 : 0;
 

     if (!m->sofdec)
        avio_seek(s->pb, last_pos, SEEK_SET);
 

     /* no need to do more */
     return 0;
 }
 

 static int64_t get_pts(AVIOContext *pb, int c)

 {

     uint8_t buf[5];
 

     buf[0] = c<0 ? avio_r8(pb) : c;
     avio_read(pb, buf+1, 4);

 
     return ff_parse_pes_pts(buf);

 }
 

 static int find_next_start_code(AVIOContext *pb, int *size_ptr,

                                 int32_t *header_state)

 {
     unsigned int state, v;
     int val, n;
 
     state = *header_state;
     n = *size_ptr;
     while (n > 0) {
         if (url_feof(pb))
             break;

         v = avio_r8(pb);

         n--;
         if (state == 0x000001) {
             state = ((state << 8) | v) & 0xffffff;
             val = state;
             goto found;
         }
         state = ((state << 8) | v) & 0xffffff;
     }
     val = -1;
  found:
     *header_state = state;
     *size_ptr = n;
     return val;
 }
 

 /**

  * Extract stream types from a program stream map

  * According to ISO/IEC 13818-1 ('MPEG-2 Systems') table 2-35

  *

  * @return number of bytes occupied by PSM in the bitstream
  */

 static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)

 {
     int psm_length, ps_info_length, es_map_length;
 

     psm_length = avio_rb16(pb);
     avio_r8(pb);
     avio_r8(pb);
     ps_info_length = avio_rb16(pb);

 
     /* skip program_stream_info */

     avio_skip(pb, ps_info_length);

     es_map_length = avio_rb16(pb);

 
     /* at least one es available? */
     while (es_map_length >= 4){

         unsigned char type      = avio_r8(pb);
         unsigned char es_id     = avio_r8(pb);
         uint16_t es_info_length = avio_rb16(pb);

         /* remember mapping from stream id to stream type */
         m->psm_es_type[es_id] = type;
         /* skip program_stream_info */

         avio_skip(pb, es_info_length);

         es_map_length -= 4 + es_info_length;
     }

     avio_rb32(pb); /* crc32 */

     return 2 + psm_length;
 }
 

 /* read the next PES header. Return its position in ppos

    (if not NULL), and its start code, pts and dts.
  */
 static int mpegps_read_pes_header(AVFormatContext *s,

                                   int64_t *ppos, int *pstart_code,

                                   int64_t *ppts, int64_t *pdts)

 {
     MpegDemuxContext *m = s->priv_data;

     int len, size, startcode, c, flags, header_len;

     int pes_ext, ext2_len, id_ext, skip;

     int64_t pts, dts;

     int64_t last_sync= avio_tell(s->pb);

  error_redo:

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

  redo:

         /* next start code (should be immediately after) */
         m->header_state = 0xff;
         size = MAX_SYNC_SIZE;

         startcode = find_next_start_code(s->pb, &size, &m->header_state);

         last_sync = avio_tell(s->pb);

     if (startcode < 0){
         if(url_feof(s->pb))
             return AVERROR_EOF;
         //FIXME we should remember header_state
         return AVERROR(EAGAIN);
     }
 

     if (startcode == PACK_START_CODE)
         goto redo;
     if (startcode == SYSTEM_HEADER_START_CODE)
         goto redo;

     if (startcode == PADDING_STREAM) {

         avio_skip(s->pb, avio_rb16(s->pb));

         goto redo;
     }
     if (startcode == PRIVATE_STREAM_2) {

         len = avio_rb16(s->pb);

         if (!m->sofdec) {
             while (len-- >= 6) {

                 if (avio_r8(s->pb) == 'S') {

                     uint8_t buf[5];

                     avio_read(s->pb, buf, sizeof(buf));

                     m->sofdec = !memcmp(buf, "ofdec", 5);
                     len -= sizeof(buf);
                     break;
                 }
             }
             m->sofdec -= !m->sofdec;
         }

         avio_skip(s->pb, len);

         goto redo;
     }

     if (startcode == PROGRAM_STREAM_MAP) {

         mpegps_psm_parse(m, s->pb);

         goto redo;
     }

     /* find matching stream */
     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
           (startcode >= 0x1e0 && startcode <= 0x1ef) ||

           (startcode == 0x1bd) || (startcode == 0x1fd)))

         goto redo;

     if (ppos) {

         *ppos = avio_tell(s->pb) - 4;

     }

     len = avio_rb16(s->pb);

     pts =

     dts = AV_NOPTS_VALUE;

     /* stuffing */
     for(;;) {

         if (len < 1)

             goto error_redo;

         c = avio_r8(s->pb);

         len--;
         /* XXX: for mpeg1, should test only bit 7 */

         if (c != 0xff)

             break;
     }
     if ((c & 0xc0) == 0x40) {
         /* buffer scale & size */

         avio_r8(s->pb);
         c = avio_r8(s->pb);

         len -= 2;
     }

     if ((c & 0xe0) == 0x20) {

         dts = pts = get_pts(s->pb, c);

         len -= 4;

         if (c & 0x10){

             dts = get_pts(s->pb, -1);

             len -= 5;
         }

     } else if ((c & 0xc0) == 0x80) {
         /* mpeg 2 PES */

         flags = avio_r8(s->pb);
         header_len = avio_r8(s->pb);

         len -= 2;
         if (header_len > len)

             goto error_redo;

         len -= header_len;

         if (flags & 0x80) {

             dts = pts = get_pts(s->pb, -1);

             header_len -= 5;

             if (flags & 0x40) {

                 dts = get_pts(s->pb, -1);

                 header_len -= 5;
             }

         }

         if (flags & 0x3f && header_len == 0){
             flags &= 0xC0;
             av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
         }

         if (flags & 0x01) { /* PES extension */

             pes_ext = avio_r8(s->pb);

             header_len--;
             /* Skip PES private data, program packet sequence counter and P-STD buffer */
             skip = (pes_ext >> 4) & 0xb;
             skip += skip & 0x9;

             if (pes_ext & 0x40 || skip > header_len){
                 av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
                 pes_ext=skip=0;
             }

             avio_skip(s->pb, skip);

             header_len -= skip;
 
             if (pes_ext & 0x01) { /* PES extension 2 */

                 ext2_len = avio_r8(s->pb);

                 header_len--;
                 if ((ext2_len & 0x7f) > 0) {

                     id_ext = avio_r8(s->pb);

                     if ((id_ext & 0x80) == 0)
                         startcode = ((startcode & 0xff) << 8) | id_ext;
                     header_len--;
                 }
             }
         }

         if(header_len < 0)
             goto error_redo;

         avio_skip(s->pb, header_len);

     }

     else if( c!= 0xf )
         goto redo;
 

     if (startcode == PRIVATE_STREAM_1) {

         startcode = avio_r8(s->pb);

         len--;
     }

     if(len<0)
         goto error_redo;

     if(dts != AV_NOPTS_VALUE && ppos){
         int i;
         for(i=0; i<s->nb_streams; i++){

             if(startcode == s->streams[i]->id &&

                s->pb->seekable /* index useless on streams anyway */) {

                 ff_reduce_index(s, i);

                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);

             }
         }
     }

     *pstart_code = startcode;
     *ppts = pts;
     *pdts = dts;
     return len;
 }
 
 static int mpegps_read_packet(AVFormatContext *s,
                               AVPacket *pkt)
 {

     MpegDemuxContext *m = s->priv_data;

     AVStream *st;

     int len, startcode, i, es_type, ret;

     int lpcm_header_len = -1; //Init to supress warning

     int request_probe= 0;

     enum AVCodecID codec_id = AV_CODEC_ID_NONE;

     enum AVMediaType type;

     int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work

 
  redo:

     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);

     if (len < 0)
         return len;

     if (startcode >= 0x80 && startcode <= 0xcf) {
         if(len < 4)
             goto skip;
 
         /* audio: skip header */
         avio_r8(s->pb);

         lpcm_header_len = avio_rb16(s->pb);

         len -= 3;
         if (startcode >= 0xb0 && startcode <= 0xbf) {
             /* MLP/TrueHD audio has a 4-byte header */
             avio_r8(s->pb);
             len--;
         }
     }
 

     /* now find stream */
     for(i=0;i<s->nb_streams;i++) {
         st = s->streams[i];
         if (st->id == startcode)
             goto found;
     }

 
     es_type = m->psm_es_type[startcode & 0xff];
         if(es_type == STREAM_TYPE_VIDEO_MPEG1){

             codec_id = AV_CODEC_ID_MPEG2VIDEO;

             type = AVMEDIA_TYPE_VIDEO;

         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){

             codec_id = AV_CODEC_ID_MPEG2VIDEO;

             type = AVMEDIA_TYPE_VIDEO;

         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
                   es_type == STREAM_TYPE_AUDIO_MPEG2){

             codec_id = AV_CODEC_ID_MP3;

             type = AVMEDIA_TYPE_AUDIO;

         } else if(es_type == STREAM_TYPE_AUDIO_AAC){

             codec_id = AV_CODEC_ID_AAC;

             type = AVMEDIA_TYPE_AUDIO;

         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){

             codec_id = AV_CODEC_ID_MPEG4;

             type = AVMEDIA_TYPE_VIDEO;

         } else if(es_type == STREAM_TYPE_VIDEO_H264){

             codec_id = AV_CODEC_ID_H264;

             type = AVMEDIA_TYPE_VIDEO;

         } else if(es_type == STREAM_TYPE_AUDIO_AC3){

             codec_id = AV_CODEC_ID_AC3;

             type = AVMEDIA_TYPE_AUDIO;

     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {

         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
         unsigned char buf[8];

         avio_read(s->pb, buf, 8);

         avio_seek(s->pb, -8, SEEK_CUR);

         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))

             codec_id = AV_CODEC_ID_CAVS;

         else

             request_probe= 1;

         type = AVMEDIA_TYPE_VIDEO;

     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {

         type = AVMEDIA_TYPE_AUDIO;

         codec_id = m->sofdec > 0 ? AV_CODEC_ID_ADPCM_ADX : AV_CODEC_ID_MP2;

     } else if (startcode >= 0x80 && startcode <= 0x87) {

         type = AVMEDIA_TYPE_AUDIO;

         codec_id = AV_CODEC_ID_AC3;

     } else if (  ( startcode >= 0x88 && startcode <= 0x8f)

                ||( startcode >= 0x98 && startcode <= 0x9f)) {
         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */

         type = AVMEDIA_TYPE_AUDIO;

         codec_id = AV_CODEC_ID_DTS;

     } else if (startcode >= 0xa0 && startcode <= 0xaf) {

         type = AVMEDIA_TYPE_AUDIO;

         if(lpcm_header_len == 6) {

             codec_id = AV_CODEC_ID_MLP;

         } else {

             /* 16 bit form will be handled as AV_CODEC_ID_PCM_S16BE */
             codec_id = AV_CODEC_ID_PCM_DVD;

         }

     } else if (startcode >= 0xb0 && startcode <= 0xbf) {

         type = AVMEDIA_TYPE_AUDIO;

         codec_id = AV_CODEC_ID_TRUEHD;

     } else if (startcode >= 0xc0 && startcode <= 0xcf) {
         /* Used for both AC-3 and E-AC-3 in EVOB files */

         type = AVMEDIA_TYPE_AUDIO;

         codec_id = AV_CODEC_ID_AC3;

     } else if (startcode >= 0x20 && startcode <= 0x3f) {

         type = AVMEDIA_TYPE_SUBTITLE;

         codec_id = AV_CODEC_ID_DVD_SUBTITLE;

     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {

         type = AVMEDIA_TYPE_VIDEO;

         codec_id = AV_CODEC_ID_VC1;

     } else {
     skip:
         /* skip packet */

         avio_skip(s->pb, len);

         goto redo;
     }

     /* no stream found: add a new stream */

     st = avformat_new_stream(s, NULL);

     if (!st)

         goto skip;

     st->id = startcode;

     st->codec->codec_type = type;
     st->codec->codec_id = codec_id;

     st->request_probe     = request_probe;

     if (codec_id != AV_CODEC_ID_PCM_S16BE)

         st->need_parsing = AVSTREAM_PARSE_FULL;

  found:

     if(st->discard >= AVDISCARD_ALL)

         goto skip;

     if (startcode >= 0xa0 && startcode <= 0xaf) {

       if (lpcm_header_len == 6 && st->codec->codec_id == AV_CODEC_ID_MLP) {

             if (len < 6)
                 goto skip;
             avio_skip(s->pb, 6);
             len -=6;
       } else {

         int b1, freq;
 
         /* for LPCM, we just skip the header and consider it is raw
            audio data */
         if (len <= 3)
             goto skip;

         avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
         b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
         avio_r8(s->pb); /* dynamic range control (0x80 = off) */

         len -= 3;
         freq = (b1 >> 4) & 3;

         st->codec->sample_rate = lpcm_freq_tab[freq];
         st->codec->channels = 1 + (b1 & 7);

         st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;

         st->codec->bit_rate = st->codec->channels *
                               st->codec->sample_rate *

                               st->codec->bits_per_coded_sample;
         if (st->codec->bits_per_coded_sample == 16)

             st->codec->codec_id = AV_CODEC_ID_PCM_S16BE;

         else if (st->codec->bits_per_coded_sample == 28)

             return AVERROR(EINVAL);

       }

     }

     ret = av_get_packet(s->pb, pkt, len);

     pkt->pts = pts;

     pkt->dts = dts;

     pkt->pos = dummy_pos;

     pkt->stream_index = st->index;

     av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",

             pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
             pkt->size);

     return (ret < 0) ? ret : 0;

 }
 

 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,

                                int64_t *ppos, int64_t pos_limit)

 {
     int len, startcode;
     int64_t pos, pts, dts;
 
     pos = *ppos;

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

         return AV_NOPTS_VALUE;
 

     for(;;) {

         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);

         if (len < 0) {

             av_dlog(s, "none (ret=%d)\n", len);

             return AV_NOPTS_VALUE;
         }

         if (startcode == s->streams[stream_index]->id &&

             dts != AV_NOPTS_VALUE) {
             break;
         }

         avio_skip(s->pb, len);

     }

     av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
             pos, dts, dts / 90000.0);

     *ppos = pos;

     return dts;

 }
 

 AVInputFormat ff_mpegps_demuxer = {

     .name           = "mpeg",

     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-PS (MPEG-2 Program Stream)"),

     .priv_data_size = sizeof(MpegDemuxContext),
     .read_probe     = mpegps_probe,
     .read_header    = mpegps_read_header,
     .read_packet    = mpegps_read_packet,
     .read_timestamp = mpegps_read_dts,

     .flags          = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,

 };

 
 #if CONFIG_VOBSUB_DEMUXER
 
 #define REF_STRING "# VobSub index file,"
 
 static int vobsub_probe(AVProbeData *p)
 {
     if (!strncmp(p->buf, REF_STRING, sizeof(REF_STRING) - 1))
         return AVPROBE_SCORE_MAX;
     return 0;
 }
 
 static int vobsub_read_header(AVFormatContext *s)
 {

     int i, ret = 0, header_parsed = 0, langidx = 0;

     MpegDemuxContext *vobsub = s->priv_data;
     char *sub_name = NULL;
     size_t fname_len;
     char *ext, *header_str;
     AVBPrint header;
     int64_t delay = 0;
     AVStream *st = NULL;
 
     sub_name = av_strdup(s->filename);
     fname_len = strlen(sub_name);
     ext = sub_name - 3 + fname_len;
     if (fname_len < 4 || *(ext - 1) != '.') {
         av_log(s, AV_LOG_ERROR, "The input index filename is too short "
                "to guess the associated .SUB file\n");
         ret = AVERROR_INVALIDDATA;
         goto end;
     }
     memcpy(ext, !strncmp(ext, "IDX", 3) ? "SUB" : "sub", 3);
     av_log(s, AV_LOG_VERBOSE, "IDX/SUB: %s -> %s\n", s->filename, sub_name);
     ret = avformat_open_input(&vobsub->sub_ctx, sub_name, &ff_mpegps_demuxer, NULL);
     if (ret < 0) {
         av_log(s, AV_LOG_ERROR, "Unable to open %s as MPEG subtitles\n", sub_name);
         goto end;
     }
 
     av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
     while (!url_feof(s->pb)) {
         char line[2048];
         int len = ff_get_line(s->pb, line, sizeof(line));
 
         if (!len)
             break;
 
         line[strcspn(line, "\r\n")] = 0;
 
         if (!strncmp(line, "id:", 3)) {
             int n, stream_id = 0;
             char id[64] = {0};
 
             n = sscanf(line, "id: %63[^,], index: %u", id, &stream_id);
             if (n != 2) {
                 av_log(s, AV_LOG_WARNING, "Unable to parse index line '%s', "
                        "assuming 'id: und, index: 0'\n", line);
                 strcpy(id, "und");
                 stream_id = 0;
             }
 
             st = avformat_new_stream(s, NULL);
             if (!st) {
                 ret = AVERROR(ENOMEM);
                 goto end;
             }
             st->id = stream_id;
             st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
             st->codec->codec_id   = AV_CODEC_ID_DVD_SUBTITLE;

             avpriv_set_pts_info(st, 64, 1, 1000);

             av_dict_set(&st->metadata, "language", id, 0);
             av_log(s, AV_LOG_DEBUG, "IDX stream[%d] id=%s\n", stream_id, id);
             header_parsed = 1;
 
         } else if (st && !strncmp(line, "timestamp:", 10)) {
             AVPacket *sub;
             int hh, mm, ss, ms;
             int64_t pos, timestamp;
             const char *p = line + 10;
 
             if (sscanf(p, "%02d:%02d:%02d:%03d, filepos: %"PRIx64,
                        &hh, &mm, &ss, &ms, &pos) != 5) {
                 av_log(s, AV_LOG_ERROR, "Unable to parse timestamp line '%s', "
                        "abort parsing\n", line);
                 break;
             }
             timestamp = (hh*3600LL + mm*60LL + ss) * 1000LL + ms + delay;
             timestamp = av_rescale_q(timestamp, (AVRational){1,1000}, st->time_base);
 
             sub = ff_subtitles_queue_insert(&vobsub->q, "", 0, 0);
             if (!sub) {
                 ret = AVERROR(ENOMEM);
                 goto end;
             }
             sub->pos = pos;
             sub->pts = timestamp;
             sub->stream_index = s->nb_streams - 1;
 
         } else if (st && !strncmp(line, "alt:", 4)) {
             const char *p = line + 4;
 
             while (*p == ' ')
                 p++;
             av_dict_set(&st->metadata, "title", p, 0);
             av_log(s, AV_LOG_DEBUG, "IDX stream[%d] name=%s\n", st->id, p);
             header_parsed = 1;
 
         } else if (!strncmp(line, "delay:", 6)) {
             int sign = 1, hh = 0, mm = 0, ss = 0, ms = 0;
             const char *p = line + 6;
 
             while (*p == ' ')
                 p++;
             if (*p == '-' || *p == '+') {
                 sign = *p == '-' ? -1 : 1;
                 p++;
             }
             sscanf(p, "%d:%d:%d:%d", &hh, &mm, &ss, &ms);
             delay = ((hh*3600LL + mm*60LL + ss) * 1000LL + ms) * sign;
 
         } else if (!strncmp(line, "langidx:", 8)) {
             const char *p = line + 8;
 
             if (sscanf(p, "%d", &langidx) != 1)
                 av_log(s, AV_LOG_ERROR, "Invalid langidx specified\n");
 
         } else if (!header_parsed) {
             if (line[0] && line[0] != '#')
                 av_bprintf(&header, "%s\n", line);
         }
     }
 
     if (langidx < s->nb_streams)
         s->streams[langidx]->disposition |= AV_DISPOSITION_DEFAULT;
 
     ff_subtitles_queue_finalize(&vobsub->q);
 
     if (!av_bprint_is_complete(&header)) {
         av_bprint_finalize(&header, NULL);
         ret = AVERROR(ENOMEM);
         goto end;
     }
     av_bprint_finalize(&header, &header_str);
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *sub_st = s->streams[i];
         sub_st->codec->extradata      = av_strdup(header_str);

         sub_st->codec->extradata_size = header.len;

     }
     av_free(header_str);
 
 end:
     av_free(sub_name);
     return ret;
 }
 
 static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     MpegDemuxContext *vobsub = s->priv_data;
     FFDemuxSubtitlesQueue *q = &vobsub->q;
     AVIOContext *pb = vobsub->sub_ctx->pb;
     int ret, psize, len16 = -1;
     AVPacket idx_pkt;
 
     ret = ff_subtitles_queue_read_packet(q, &idx_pkt);
     if (ret < 0)
         return ret;
 
     /* compute maximum packet size using the next packet position. This is
      * useful when the len in the header is non-sense */
     if (q->current_sub_idx < q->nb_subs) {
         psize = q->subs[q->current_sub_idx].pos - idx_pkt.pos;
     } else {
         int64_t fsize = avio_size(pb);
         psize = fsize < 0 ? 0xffff : fsize - idx_pkt.pos;
     }
 
     avio_seek(pb, idx_pkt.pos, SEEK_SET);
 
     av_init_packet(pkt);
     pkt->size = 0;
     pkt->data = NULL;
 
     do {
         int n, to_read, startcode;
         int64_t pts, dts;
 
         ret = mpegps_read_pes_header(vobsub->sub_ctx, NULL, &startcode, &pts, &dts);
         if (ret < 0)
             return ret;
         to_read = ret & 0xffff;
 
         /* this prevents reads above the current packet */
         if (pkt->size + to_read > psize)
             break;
 
         /* if the len is computed, we check for overread */
         if (len16 != -1 && pkt->size + to_read > len16)
             break;
 
         /* the current chunk doesn't match the stream index (unlikely) */
         if ((startcode & 0x1f) != idx_pkt.stream_index)
             break;
 
         ret = av_grow_packet(pkt, to_read);
         if (ret < 0)
             return ret;
 
         n = avio_read(pb, pkt->data + (pkt->size - to_read), to_read);
         if (n < to_read)
             pkt->size -= to_read - n;
 
         /* first chunk contains the total len of the packet to raise */
         if (len16 == -1 && n > 2)
             len16 = AV_RB16(pkt->data);
     } while (len16 != -1 && pkt->size != len16);
 
     pkt->pts = pkt->dts = idx_pkt.pts;
     pkt->pos = idx_pkt.pos;
     pkt->stream_index = idx_pkt.stream_index;
 
     return 0;
 }
 
 static int vobsub_read_seek(AVFormatContext *s, int stream_index,
                             int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     MpegDemuxContext *vobsub = s->priv_data;

 
     /* Rescale requested timestamps based on the first stream (timebase is the
      * same for all subtitles stream within a .idx/.sub). Rescaling is done just
      * like in avformat_seek_file(). */
     if (stream_index == -1 && s->nb_streams != 1) {
         AVRational time_base = s->streams[0]->time_base;
         ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
         min_ts = av_rescale_rnd(min_ts, time_base.den,
                                 time_base.num * (int64_t)AV_TIME_BASE,
                                 AV_ROUND_UP   | AV_ROUND_PASS_MINMAX);
         max_ts = av_rescale_rnd(max_ts, time_base.den,
                                 time_base.num * (int64_t)AV_TIME_BASE,
                                 AV_ROUND_DOWN | AV_ROUND_PASS_MINMAX);
     }
 

     return ff_subtitles_queue_seek(&vobsub->q, s, stream_index,
                                    min_ts, ts, max_ts, flags);
 }
 
 static int vobsub_read_close(AVFormatContext *s)
 {
     MpegDemuxContext *vobsub = s->priv_data;
     ff_subtitles_queue_clean(&vobsub->q);
     if (vobsub->sub_ctx)
         avformat_close_input(&vobsub->sub_ctx);
     return 0;
 }
 
 AVInputFormat ff_vobsub_demuxer = {
     .name           = "vobsub",
     .long_name      = NULL_IF_CONFIG_SMALL("VobSub subtitle format"),
     .priv_data_size = sizeof(MpegDemuxContext),
     .read_probe     = vobsub_probe,
     .read_header    = vobsub_read_header,
     .read_packet    = vobsub_read_packet,
     .read_seek2     = vobsub_read_seek,
     .read_close     = vobsub_read_close,
     .flags          = AVFMT_SHOW_IDS,
     .extensions     = "idx",
 };
 #endif