[Libav-user] Issues seeking MKV file.

[Bob Kirnum]

Apologies for top-posting, hopefully this reply is better.

I had a newer version of the FFmpeg source on a CentOS 7 image (we are
currently using libavformat 56.25.101).  Added some debug to ffprobe.c and
it still shows the nb_index_entries as empty after the call to
avformat_open_input.  MKVToolNix v26.0.0 indicates there are 10 entries in
the Cues section, each corresponding to a key frame as reported by ffprobe.

<<
./ffprobe ./test.mkv
ffprobe version N-85966-g78aa938 Copyright (c) 2007-2017 the FFmpeg
developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-11)
  configuration: --prefix=/root/ffmpeg_build
--extra-cflags=-I/root/ffmpeg_build/include
--extra-ldflags='-L/root/ffmpeg_build/lib -ldl' --bindir=/root/bin
--pkg-config-flags=--static --enable-gpl --enable-nonfree
--enable-libfdk_aac --enable-libfreetype --enable-libmp3lame
--enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264
--enable-libx265
  libavutil      55. 62.100 / 55. 62.100
  libavcodec     57. 95.100 / 57. 95.100
  libavformat    57. 72.101 / 57. 72.101
  libavdevice    57.  7.100 / 57.  7.100
  libavfilter     6. 88.100 /  6. 88.100
  libswscale      4.  7.101 /  4.  7.101
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
Input #0, matroska,webm, from './test.mkv':
  Metadata:
    COMPATIBLE_BRANDS: isomiso2avc1mp41
    MAJOR_BRAND     : isom
    MINOR_VERSION   : 512
    ENCODER         : Lavf57.41.100
  Duration: 00:00:40.04, start: 0.000000, bitrate: 1093 kb/s
    Stream #0:0: Video: vp8, yuv420p(progressive), 1280x690, SAR 1:1 DAR
128:69, 23.98 fps, 23.98 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      HANDLER_NAME    : VideoHandler
      ENCODER         : Lavc57.48.101 libvpx
      DURATION        : 00:00:40.040000000
    Stream #0:1: Audio: amr_nb (8[0][0][0] / 0x0038), 8000 Hz, mono, flt,
12 kb/s (default)
    Metadata:
      HANDLER_NAME    : SoundHandler
      DURATION        : 00:00:39.160000000
>>

The debug output added.

<<
fmt_ctx(0x4239960)->streams[0](nb_index_entries 1 index_entries(pos 1022
timestamp 0))
fmt_ctx(0x4239960)->streams[1](nb_index_entries 1 index_entries(pos 1022
timestamp 0))
>>

The debug.

<<
    /* bind a decoder to each input stream */
    for (i = 0; i < fmt_ctx->nb_streams; i++) {
        InputStream *ist = &ifile->streams[i];
        AVStream *stream = fmt_ctx->streams[i];
        AVCodec *codec;

        ist->st = stream;


/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        if (fmt_ctx->streams[i]->nb_index_entries > 0)
        {
            int j;
            for (j = 0; j < fmt_ctx->streams[i]->nb_index_entries; j++)
            {
                av_log(NULL, AV_LOG_INFO,
"fmt_ctx(%p)->streams[%d](nb_index_entries %d index_entries(pos %jd
timestamp %jd))\n"
                    , fmt_ctx
                    , i
                    , fmt_ctx->streams[i]->nb_index_entries
                    , fmt_ctx->streams[i]->index_entries[j].pos
                    , fmt_ctx->streams[i]->index_entries[j].timestamp
                );
            }
        }

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

        if (stream->codecpar->codec_id == AV_CODEC_ID_PROBE) {
>>
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