Problem with h264_v4l2m2m

[ForsakenNGS]

In some cases (mainly observed when streaming to one of my tablets) plex will set the option -segment_format matroska which will cause the encoding to fail if h264_v4l2m2m is used instead of libx264.

Commandline example:

ffmpeg -codec:0 hevc -analyzeduration 20000000 -probesize 20000000 -i '/path/to/my/video.mkv' 
  -filter_complex '[0:0]scale=w=1920:h=1080:force_divisible_by=4[0];[0]format=pix_fmts=yuv420p|nv12[1]' -map '[1]' -metadata:s:0 language=jpn 
  -codec:0 h264_v4l2m2m -crf:0 10 -maxrate:0 50M -bufsize:0 10M -r:0 23.809999999999999 -preset:0 veryfast -level:0 4.0 
  -x264opts:0 subme=0:me_range=4:rc_lookahead=10:me=dia:no_chroma_me:8x8dct=0:partitions=none 
  -force_key_frames:0 'expr:gte(t,n_forced*1)' -map 0:1 -metadata:s:1 language=jpn -codec:1 copy -copypriorss:1 0 
  -segment_format matroska -f ssegment -individual_header_trailer 0 -flags +global_header -segment_header_filename header 
  -segment_time 1 -segment_start_number 0 -segment_copyts 1 -segment_time_delta 0.0625 
  -segment_list 'http://127.0.0.1:32400/video/:/transcode/session/somehash-com-plexapp-android/sessionid/manifest?X-Plex-Http-Pipeline=infinite' 
  -segment_list_type csv -segment_list_size 5 -segment_list_separate_stream_times 1 -segment_list_unfinished 1 
  -segment_format_options output_ts_offset=10 -max_delay 5000000 -avoid_negative_ts disabled -map_metadata:g -1 
  -map_metadata:c -1 -map_chapters -1 media-%05d.ts -start_at_zero -copyts -vsync cfr -y -nostats -loglevel_plex error 
  -progressurl http://127.0.0.1:32400/video/:/transcode/session/somehash-com-plexapp-android/sessionid/progress

The output is the following:

[h264_v4l2m2m @ 0x2344880] Using device /dev/video11
[h264_v4l2m2m @ 0x2344880] driver 'bcm2835-codec' on card 'bcm2835-codec-encode' in mplane mode
[h264_v4l2m2m @ 0x2344880] requesting formats: output=YU12 capture=H264
[h264_v4l2m2m @ 0x2344880] Failed to set gop size: Invalid argument
[stream_segment,ssegment @ 0x38bf3d0] Opening 'header' for writing
Output #0, stream_segment,ssegment, to 'media-%05d.ts':
  Metadata:
    encoder         : Lavf58.65.101
    Stream #0:0(jpn): Video: h264, yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 23.81 fps, 1k tbn (default)
    Metadata:
      encoder         : Lavc58.117.101 h264_v4l2m2m
    Stream #0:1(jpn): Audio: aac (LC), 48000 Hz, stereo, fltp (default)
    Metadata:
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      title           : Japanese (FUNIMATION)
      BPS             : 256000
      DURATION        : 00:23:40.117000000
      NUMBER_OF_FRAMES: 66568
      NUMBER_OF_BYTES : 45443755
      _STATISTICS_WRITING_APP: mkvmerge v61.0.0 ('So') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-12-20 12:39:52
av_interleaved_write_frame(): Invalid data found when processing input
Error writing trailer of media-%05d.ts: Invalid data found when processing input
frame=    2 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x    
video:0kB audio:16kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Conversion failed!

When running the exact same commandline and only swapping out h264_v4l2m2m for libx264 everything works fine.

[tmm1]

You can try adding -bsf:v h264_mp4toannexb

[ForsakenNGS]

You can try adding -bsf:v h264_mp4toannexb

Thanks for the tip. Unfortunally that did not help. I now implemented the feature to remove arguments and just removed -segment_format matroska alltogether. I'm not sure why plex sets this option in this case, so unfortunally this could have consequences I am not aware of. For now it is certainly better than a non-working transcode I guess :D

[ForsakenNGS]

This definitly needs a cleaner solution. When trying to download the episode I get the same error for the commandline

ffmpeg -codec:0 hevc -analyzeduration 20000000 -probesize 20000000 -i '/path/to/my/video.mkv' -map_inlineass 0:2 
  -filter_complex '[0:0]scale=w=1920:h=1080:force_divisible_by=4[0];[0]format=pix_fmts=yuv420p|nv12[1];[1]inlineass=font_scale=1.000000:font_path=/usr/lib/plexmediaserver/Resources/Fonts/NotoSans-Medium.otf:fontconfig_file=/usr/lib/plexmediaserver/Resources/fonts.conf:language=en[2]' 
  -map '[2]' -metadata:s:0 language=jpn -codec:0 h264_v4l2m2m -crf:0 10 -maxrate:0 50M -bufsize:0 10M -r:0 23.975999999999999 -preset:0 veryfast -level:0 5.2 
  -x264opts:0 subme=0:me_range=4:rc_lookahead=10:me=dia:no_chroma_me:8x8dct=0:partitions=none -map 0:1 
  -metadata:s:1 language=jpn -codec:1 copy -copypriorss:1 0 -f matroska -map_metadata -1 -map_chapters -1 Output.mkv 
  -map 0:2 -f null -codec ass nullfile -y -nostats -loglevel quiet -loglevel_plex error 
  -progressurl http://127.0.0.1:32400/video/:/transcode/session/sessionid/sessionid/progress

[ForsakenNGS]

For now I replaced the offending flags by -segment_format mpegts and -f mpegts respectively, that does seem to work in most cases. Yet I still consider this an issue. Most likely this will have impact on the available features like multiple audio-streams, subtitles, meta-data and similar things.