FFmpeg process go over 100% when adding null audio track

[Anh Trinh]

Summary of the bug:
How to reproduce:

% ffmpeg -i myvideo.mp4 -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=48000 -y -acodec aac -ac 1 -b:a 128k -ar 48000 -vcodec copy -video_track_timescale 90000 output/myvideo_encoded.mp4

ffmpeg version 6.0-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 8 (Debian 8.3.0-6)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100

===================== PLEASE NOTICE THIS ===============================

[h264 @ 0x5a1c100] error while decoding MB 75 44, bytestream -29
[h264 @ 0x5a1c100] concealing 54 DC, 54 AC, 54 MV errors in I frame

===================== /////////////////// ===============================

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '20230402-starbulls_rosenheim-tilburg_trappers-1680456945-P1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
    creation_time   : 2023-04-02T17:20:15.000000Z
    encoder         : Dartfish Software 11.1.517.0 (Recorder)
    encoder-eng     : Dartfish Software 11.1.517.0 (Recorder)
    comment         : XEncoder (city/sz)
    comment-eng     : XEncoder (city/sz)
  Duration: 03:01:32.40, start: 0.000000, bitrate: 4129 kb/s
  Stream #0:0[0x1](eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 4127 kb/s, 30 fps, 30 tbr, 30 tbn (default)
    Metadata:
      creation_time   : 2023-04-02T17:20:15.000000Z
      vendor_id       : [0][0][0][0]
      encoder         : H.264/AVC
Input #1, lavfi, from 'anullsrc=channel_layout=stereo:sample_rate=48000':
  Duration: N/A, start: 0.000000, bitrate: 768 kb/s
  Stream #1:0: Audio: pcm_u8, 48000 Hz, stereo, u8, 768 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #1:0 -> #0:1 (pcm_u8 (native) -> aac (native))
Press [q] to stop, [?] for help
Output #0, mp4, to 'output/encoded_20230402-starbulls_rosenheim-tilburg_trappers-1680456945-P1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
    comment-eng     : XEncoder (city/sz)
    comment         : XEncoder (city/sz)
    encoder         : Lavf60.3.100
  Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 4127 kb/s, 30 fps, 30 tbr, 90k tbn (default)
    Metadata:
      creation_time   : 2023-04-02T17:20:15.000000Z
      vendor_id       : [0][0][0][0]
      encoder         : H.264/AVC
  Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc60.3.100 aac


frame=326775 fps=10473 q=-1.0 Lsize= 5503970kB time=04:07:24.84 bitrate=3037.3kbits/s speed= 476x    

As you can see, the reported duration is 03:01:32.40, but the encoding just goes on and on and it doesn't want to complete (see the last output, it get to 04:07:24.84). I have to Ctrl + C to stop it.

Remove the anullsrc stuff in the command line stop this from happening. Please also notice some error in the output above:

[h264 @ 0x5a1c100] error while decoding MB 75 44, bytestream -29
[h264 @ 0x5a1c100] concealing 54 DC, 54 AC, 54 MV errors in I frame

The above command works in 5.1.1, so something in 6.0 is causing this issue.

[Elon Musk]

Missing -shortest