concat demuxer does not work for two h264 streams

[Carl Eugen Hoyos]

​http://thread.gmane.org/gmane.comp.video.ffmpeg.user/51570

A user uploaded two h264/mp4 samples that cannot be demuxed with the concat demuxer.

$ ffmpeg -i concat-test-1_cut.mp4 -i concat-test-2.mp4
ffmpeg version N-62765-g8120668 Copyright (c) 2000-2014 the FFmpeg developers
  built on Apr 28 2014 22:40:02 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      52. 79.100 / 52. 79.100
  libavcodec     55. 59.100 / 55. 59.100
  libavformat    55. 37.101 / 55. 37.101
  libavdevice    55. 13.100 / 55. 13.100
  libavfilter     4.  4.100 /  4.  4.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 18.100 /  0. 18.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'concat-test-1_cut.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.37.101
  Duration: 00:00:00.54, start: 0.000000, bitrate: 37373 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 36980 kb/s, 50 fps, 50 tbr, 12800 tbn, 100 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 383 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'concat-test-2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.19.104
  Duration: 00:00:01.04, start: 0.000000, bitrate: 8143 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 7751 kb/s, 50 fps, 50 tbr, 12800 tbn, 100 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 387 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
At least one output file must be specified

$ ffmpeg -f concat -i concat-test -qscale 2 out.avi
ffmpeg version N-62765-g8120668 Copyright (c) 2000-2014 the FFmpeg developers
  built on Apr 28 2014 22:40:02 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      52. 79.100 / 52. 79.100
  libavcodec     55. 59.100 / 55. 59.100
  libavformat    55. 37.101 / 55. 37.101
  libavdevice    55. 13.100 / 55. 13.100
  libavfilter     4.  4.100 /  4.  4.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 18.100 /  0. 18.100
  libpostproc    52.  3.100 / 52.  3.100
[concat @ 0x2359d00] Estimating duration from bitrate, this may be inaccurate
Input #0, concat, from 'concat-test':
  Duration: 00:00:00.00, start: 0.000000, bitrate: 19047 kb/s
    Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 36980 kb/s, 50 fps, 50 tbr, 12800 tbn, 100 tbc
    Stream #0:1: Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 383 kb/s
Please use -q:a or -q:v, -qscale is ambiguous
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf55.37.101
    Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 50 tbn, 50 tbc
    Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo, fltp, 192 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mpeg4)
  Stream #0:1 -> #0:1 (aac -> ac3)
Press [q] to stop, [?] for help
[h264 @ 0x33acf80] left block unavailable for requested intra mode at 0 0
[h264 @ 0x33acf80] error while decoding MB 0 0, bytestream 299
[h264 @ 0x33acf80] concealing 8160 DC, 8160 AC, 8160 MV errors in I frame
[h264 @ 0x33f2120] error while decoding MB 33 1, bytestream -20
[h264 @ 0x33f2120] concealing 8056 DC, 8056 AC, 8056 MV errors in P frame
[h264 @ 0x3485600] top block unavailable for requested intra mode at 39 0
[h264 @ 0x3485600] error while decoding MB 39 0, bytestream 3505
[h264 @ 0x3485600] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x3518ae0] Reference 3 >= 2
[h264 @ 0x3518ae0] error while decoding MB 4 0, bytestream 4204
[h264 @ 0x3518ae0] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x35abfc0] Reference 2 >= 2
[h264 @ 0x35abfc0] error while decoding MB 16 0, bytestream 592
[h264 @ 0x35abfc0] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x363f4a0] Reference 5 >= 4
[h264 @ 0x363f4a0] error while decoding MB 15 0, bytestream 3022
[h264 @ 0x363f4a0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x36d2980] Reference 3 >= 3
[h264 @ 0x36d2980] error while decoding MB 19 0, bytestream 649
[h264 @ 0x36d2980] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x3765e60] top block unavailable for requested intra4x4 mode -1 at 12 0
[h264 @ 0x3765e60] error while decoding MB 12 0, bytestream 263
[h264 @ 0x3765e60] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x37f9340] Reference 2 >= 2
[h264 @ 0x37f9340] error while decoding MB 12 0, bytestream 811
[h264 @ 0x37f9340] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x33acf80] top block unavailable for requested intra mode at 11 0
[h264 @ 0x33acf80] error while decoding MB 11 0, bytestream 6584
[h264 @ 0x33acf80] Cannot use next picture in error concealment
[h264 @ 0x33acf80] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33f2120] Reference 2 >= 2
[h264 @ 0x33f2120] error while decoding MB 22 0, bytestream 3077
[h264 @ 0x33f2120] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x3485600] Reference 5 >= 5
[h264 @ 0x3485600] error while decoding MB 7 0, bytestream 10468
[h264 @ 0x3485600] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3518ae0] left block unavailable for requested intra mode at 0 0
[h264 @ 0x3518ae0] error while decoding MB 0 0, bytestream 21667
[h264 @ 0x3518ae0] concealing 8160 DC, 8160 AC, 8160 MV errors in I frame
[h264 @ 0x35abfc0] top block unavailable for requested intra4x4 mode -1 at 1 0
[h264 @ 0x35abfc0] error while decoding MB 1 0, bytestream 13024
[h264 @ 0x35abfc0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x363f4a0] Reference 5 >= 4
[h264 @ 0x363f4a0] error while decoding MB 3 0, bytestream 14554
[h264 @ 0x363f4a0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x36d2980] Reference 9 >= 5
[h264 @ 0x36d2980] error while decoding MB 6 0, bytestream 11751
[h264 @ 0x36d2980] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3765e60] Reference 5 >= 5
[h264 @ 0x3765e60] error while decoding MB 40 0, bytestream 15076
[h264 @ 0x3765e60] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x37f9340] Reference 4 >= 4
[h264 @ 0x37f9340] error while decoding MB 2 0, bytestream 20757
[h264 @ 0x37f9340] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33acf80] top block unavailable for requested intra4x4 mode -1 at 5 0
[h264 @ 0x33acf80] error while decoding MB 5 0, bytestream 19083
[h264 @ 0x33acf80] Cannot use next picture in error concealment
[h264 @ 0x33acf80] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33f2120] Reference 5 >= 5
[h264 @ 0x33f2120] error while decoding MB 0 0, bytestream 17954
[h264 @ 0x33f2120] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3485600] Reference 5 >= 5
[h264 @ 0x3485600] error while decoding MB 10 0, bytestream 19940
[h264 @ 0x3485600] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3518ae0] top block unavailable for requested intra mode at 33 0
[h264 @ 0x3518ae0] error while decoding MB 33 0, bytestream 15571
[h264 @ 0x3518ae0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x35abfc0] Reference 6 >= 5
[h264 @ 0x35abfc0] error while decoding MB 14 0, bytestream 20061
[h264 @ 0x35abfc0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x363f4a0] top block unavailable for requested intra mode at 1 0
[h264 @ 0x363f4a0] error while decoding MB 1 0, bytestream 19385
[h264 @ 0x363f4a0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x36d2980] top block unavailable for requested intra mode at 106 0
[h264 @ 0x36d2980] error while decoding MB 106 0, bytestream 18693
[h264 @ 0x36d2980] concealing 8103 DC, 8103 AC, 8103 MV errors in P frame
[h264 @ 0x3765e60] Reference 5 >= 5
[h264 @ 0x3765e60] error while decoding MB 0 0, bytestream 20609
[h264 @ 0x3765e60] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x37f9340] Reference 5 >= 5
[h264 @ 0x37f9340] error while decoding MB 10 0, bytestream 25742
[h264 @ 0x37f9340] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33acf80] Reference 5 >= 5
[h264 @ 0x33acf80] error while decoding MB 8 0, bytestream 19745
[h264 @ 0x33acf80] Cannot use next picture in error concealment
[h264 @ 0x33acf80] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33f2120] top block unavailable for requested intra4x4 mode -1 at 5 0
[h264 @ 0x33f2120] error while decoding MB 5 0, bytestream 22778
[h264 @ 0x33f2120] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3485600] Reference 11 >= 5
[h264 @ 0x3485600] error while decoding MB 13 0, bytestream 23670
[h264 @ 0x3485600] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3518ae0] Reference 5 >= 5
[h264 @ 0x3518ae0] error while decoding MB 4 0, bytestream 25350
[h264 @ 0x3518ae0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x35abfc0] concealing 8158 DC, 8158 AC, 8158 MV errors in P frame
[h264 @ 0x363f4a0] top block unavailable for requested intra mode at 52 0
[h264 @ 0x363f4a0] error while decoding MB 52 0, bytestream 24663
[h264 @ 0x363f4a0] concealing 8157 DC, 8157 AC, 8157 MV errors in P frame
[h264 @ 0x36d2980] Reference 2 >= 2
[h264 @ 0x36d2980] error while decoding MB 25 0, bytestream 13254
[h264 @ 0x36d2980] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x3765e60] top block unavailable for requested intra4x4 mode -1 at 4 0
[h264 @ 0x3765e60] error while decoding MB 4 0, bytestream 26838
[h264 @ 0x3765e60] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x37f9340] Reference 9 >= 5
[h264 @ 0x37f9340] error while decoding MB 25 0, bytestream 26875
[h264 @ 0x37f9340] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33acf80] Cannot use next picture in error concealment
[h264 @ 0x33acf80] concealing 8097 DC, 8097 AC, 8097 MV errors in P frame
[h264 @ 0x33f2120] Reference 5 >= 5
[h264 @ 0x33f2120] error while decoding MB 3 0, bytestream 29120
[h264 @ 0x33f2120] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3485600] Reference 7 >= 5
[h264 @ 0x3485600] error while decoding MB 12 0, bytestream 28072
[h264 @ 0x3485600] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3518ae0] Reference 8 >= 5
[h264 @ 0x3518ae0] error while decoding MB 9 0, bytestream 32759
[h264 @ 0x3518ae0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x35abfc0] Reference 5 >= 5
[h264 @ 0x35abfc0] error while decoding MB 12 0, bytestream 30443
[h264 @ 0x35abfc0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x363f4a0] Reference 5 >= 5
[h264 @ 0x363f4a0] error while decoding MB 8 0, bytestream 29151
[h264 @ 0x363f4a0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x36d2980] concealing 8137 DC, 8137 AC, 8137 MV errors in B frame
[h264 @ 0x3765e60] Reference 7 >= 5
[h264 @ 0x3765e60] error while decoding MB 7 0, bytestream 28497
[h264 @ 0x3765e60] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x37f9340] top block unavailable for requested intra4x4 mode -1 at 8 0
[h264 @ 0x37f9340] error while decoding MB 8 0, bytestream 33653
[h264 @ 0x37f9340] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x33acf80] Reference 2 >= 2
[h264 @ 0x33acf80] error while decoding MB 2 0, bytestream 17660
[h264 @ 0x33acf80] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x33f2120] Reference 5 >= 5
[h264 @ 0x33f2120] error while decoding MB 11 0, bytestream 32264
[h264 @ 0x33f2120] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3485600] Reference 8 >= 5
[h264 @ 0x3485600] error while decoding MB 20 0, bytestream 57902
[h264 @ 0x3485600] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x3518ae0] Reference 3 >= 2
[h264 @ 0x3518ae0] error while decoding MB 37 0, bytestream 14829
[h264 @ 0x3518ae0] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x35abfc0] top block unavailable for requested intra4x4 mode -1 at 32 0
[h264 @ 0x35abfc0] error while decoding MB 32 0, bytestream 33738
[h264 @ 0x35abfc0] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
[h264 @ 0x363f4a0] Reference 2 >= 2
[h264 @ 0x363f4a0] error while decoding MB 16 0, bytestream 13330
[h264 @ 0x363f4a0] concealing 8160 DC, 8160 AC, 8160 MV errors in B frame
[h264 @ 0x36d2980] Reference 5 >= 5
[h264 @ 0x36d2980] error while decoding MB 4 0, bytestream 44562
[h264 @ 0x36d2980] concealing 8160 DC, 8160 AC, 8160 MV errors in P frame
frame=   79 fps=0.0 q=2.0 Lsize=    4085kB time=00:00:01.58 bitrate=21182.2kbits/s
video:4037kB audio:36kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.313807%

The output file contains the video from the first file, then only artefacts.
The following works fine:

$ ffmpeg -i concat-test-1_cut.mp4 -vcodec copy -vbsf h264_mp4toannexb out1.h264
$ ffmpeg -i concat-test-2.mp4 -vcodec copy -vbsf h264_mp4toannexb out2.h264
$ cat out1.h264 out2.h264 >out.h264

out.h264 can be decoded with FFmpeg.

[Carl Eugen Hoyos]

Works fine with -auto_convert 1

[Serghei]

1