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• ffmpeg doesn't detect the subtitle format (webvtt) and refuses to copy it

  29 novembre 2023, par Thomas

  I am trying to re-encode the audio on some video files.
I want to copy the video and subtitles without touching them, however, ffmpeg doesn't detect the format of the subtitle (which is webvtt) and refuses to do anything.

  



  fmpeg -copy_unknown -analyzeduration 2000M -probesize 2000M -i input.mkv -map_metadata 0 -map 0 -c copy -c:a:0 aac -b:a 384k output.mkv

  



  [matroska,webm @ 0x5597558e4040] Unknown/unsupported AVCodecID S_TEXT/WEBVTT.
[matroska,webm @ 0x5597558e4040] Could not find codec parameters for stream 2 (Subtitle: none): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Guessed Channel Layout for Input Stream #0.1 : 5.1
Input #0, matroska,webm, from 'input.mkv':
  Metadata:
    encoder         : libebml v1.3.9 + libmatroska v1.5.2
    creation_time   : 2020-03-05T09:03:02.000000Z
  Duration: 00:56:33.26, start: 0.000000, bitrate: 3597 kb/s
    Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Metadata:
      BPS-eng         : 3340067
      DURATION-eng    : 00:56:33.140000000
      NUMBER_OF_FRAMES-eng: 81354
      NUMBER_OF_BYTES-eng: 1416664616
      _STATISTICS_WRITING_APP-eng: mkvmerge v38.0.0 ('The Silent Type') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2020-03-05 09:03:02
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
    Stream #0:1: Audio: eac3, 48000 Hz, 5.1, fltp (default)
    Metadata:
      BPS-eng         : 256000
      DURATION-eng    : 00:56:33.248000000
      NUMBER_OF_FRAMES-eng: 106039
      NUMBER_OF_BYTES-eng: 108583936
      _STATISTICS_WRITING_APP-eng: mkvmerge v38.0.0 ('The Silent Type') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2020-03-05 09:03:02
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
    Stream #0:2(eng): Subtitle: none (default)
    Metadata:
      BPS-eng         : 38
      DURATION-eng    : 00:54:47.388000000
      NUMBER_OF_FRAMES-eng: 514
      NUMBER_OF_BYTES-eng: 15766
      _STATISTICS_WRITING_APP-eng: mkvmerge v38.0.0 ('The Silent Type') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2020-03-05 09:03:02
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES

Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (eac3 (native) -> aac (native))
  Stream #0:2 -> #0:2 (copy)

[aac @ 0x5597b06ae000] Using a PCE to encode channel layout "5.1(side)"
[matroska @ 0x5597b06ab540] Subtitle codec 0 is not supported.
Could not write header for output file #0 (incorrect codec parameters ?): Function not implemented
Error initializing output stream 0:1 -- 
[aac @ 0x5597b06ae000] Qavg: -nan
Conversion failed!


  



  VLC shows it as WebVTT and displays the subtitles correctly :

  



  

  



  MediaInfo also detects properly as webvtt :

  



  Text
ID                                       : 3
Format                                   : S_TEXT/WEBVTT
Codec ID                                 : S_TEXT/WEBVTT
Duration                                 : 54 min 47 s
Bit rate                                 : 38 b/s
Count of elements                        : 514
Stream size                              : 15.4 KiB (0%)
Language                                 : English
Default                                  : Yes
Forced                                   : No


  



  My ffmpeg was built with webvtt :

  



  $ ffmpeg -codecs | grep VTT
ffmpeg version n4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9.3.0 (Arch Linux 9.3.0-1)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
 DES... webvtt               WebVTT subtitle


  



  How can I tell ffmpeg "this is webvtt, just copy it please !" ?

  



  EDIT : RESOLVED (thanks @Gyan)

  



  To force the decoder, -c:s webvtt must be set before the input :
fmpeg -analyzeduration 50M -probesize 50M -c:s webvtt -i input.mkv ...

  


• what is the correct command using gstreamer to convert mp4 to 264 file ?

  25 mars 2020, par hilow

  My english is pool, i am sorry !

  I use ffmpeg and gstreamer convert mp4 file to 264 format, but the output file is different.
  The question is :

  • 1.Why they are different file ?

  • 2.What is the level mean in gst-discoverer-1.0 ?

    Use ffmpeg it is Codec:     video/x-h264, ...... level=(string)1.2.

    Use gstreamer it is Codec:     video/x-h264, ...... level=(string)3.

  • 3.How to use gstreamer to convert the correct 264 file ?

  The original video file is come from https://github.com/notedit/media-server-go-demo/blob/master/video-mixer/public/big_buck_bunny.mp4 .

  command :

  gst-launch-1.0 filesrc location=big_buck_bunny.mp4 ! \
  
      qtdemux name=demux \
  
        demux.video_0 ! queue ! \
  
        decodebin ! \
  
        videoconvert ! \
  
        videoscale ! \
  
        videorate ! \
  
        video/x-raw,width=320,height=240,framerate=15/1,pixel-aspect-ratio=1/1,level=1.2 ! \
  
        x264enc bframes=0 byte-stream=true bitrate=9000 ! \
  
        filesink location=videogst.264
  
  
  
  ffmpeg -i big_buck_bunny.mp4 -f h264 -vcodec libx264 -s 320x240 -bf 0 -r 15 videoffmpeg.264

  output file :

  -rw-r--r-- 1 xxx staff 1.9M 3 25 13:39 videoffmpeg.264
  
  -rw-r--r-- 1 xxx staff 17M 3 25 13:40 videogst.264

  video codec :

  xxx@xxxs-MacBook-Pro resource %  gst-discoverer-1.0 videoffmpeg.264 -v
  
  Analyzing file:///Users/xxx/tool/resource/videoffmpeg.264
  
  Done discovering file:///Users/xxx/tool/resource/videoffmpeg.264
  
  
  
  Topology:
  
    video: video/x-h264, width=(int)320, height=(int)240, framerate=(fraction)15/1, chroma-format=(string)4:2:0, bit-depth-luma=(uint)8, bit-depth-chroma=(uint)8, parsed=(boolean)true, stream-format=(string)avc, alignment=(string)au, profile=(string)high, level=(string)1.2, codec_data=(buffer)0164000cffe100176764000cacb20283f420000003002000000303c1e2854901000668ebc3cb22c0
  
      Tags:
  
        视频编码: H.264 (High Profile)
  
  
  
      Codec:
  
        video/x-h264, width=(int)320, height=(int)240, framerate=(fraction)15/1, chroma-format=(string)4:2:0, bit-depth-luma=(uint)8, bit-depth-chroma=(uint)8, parsed=(boolean)true, stream-format=(string)avc, alignment=(string)au, profile=(string)high, level=(string)1.2, codec_data=(buffer)0164000cffe100176764000cacb20283f420000003002000000303c1e2854901000668ebc3cb22c0
  
      Additional info:
  
        None
  
      Stream ID: 349989c8845fcc23360fb0ab02ea7510051b926669bf8f3862879823fbab6daf
  
      Width: 320
  
      Height: 240
  
      Depth: 24
  
      Frame rate: 15/1
  
      Pixel aspect ratio: 1/1
  
      Interlaced: false
  
      Bitrate: 0
  
      Max bitrate: 0
  
  
  
  Properties:
  
    Duration: 0:01:32.995000000
  
    Seekable: yes
  
    Live: no
  
    Tags:
  
        视频编码: H.264 (High Profile)
  
  
  
  
  
  xxx@xxxs-MacBook-Pro resource % gst-discoverer-1.0 videogst.264 -v
  
  Analyzing file:///Users/xxx/tool/resource/videogst.264
  
  Done discovering file:///Users/xxx/tool/resource/videogst.264
  
  
  
  Topology:
  
    video: video/x-h264, pixel-aspect-ratio=(fraction)1/1, width=(int)320, height=(int)240, framerate=(fraction)15/1, chroma-format=(string)4:2:0, bit-depth-luma=(uint)8, bit-depth-chroma=(uint)8, parsed=(boolean)true, stream-format=(string)avc, alignment=(string)au, profile=(string)high, level=(string)3, codec_data=(buffer)0164001effe1001d6764001eacb20283f602d4180416940000030004000003007a3c58b92001000568ebccb22c
  
      Tags:
  
        视频编码: H.264 (High Profile)
  
  
  
      Codec:
  
        video/x-h264, pixel-aspect-ratio=(fraction)1/1, width=(int)320, height=(int)240, framerate=(fraction)15/1, chroma-format=(string)4:2:0, bit-depth-luma=(uint)8, bit-depth-chroma=(uint)8, parsed=(boolean)true, stream-format=(string)avc, alignment=(string)au, profile=(string)high, level=(string)3, codec_data=(buffer)0164001effe1001d6764001eacb20283f602d4180416940000030004000003007a3c58b92001000568ebccb22c
  
      Additional info:
  
        None
  
      Stream ID: fb99f4104b347e5682d52c0bd65bcee91b765e42f89ce2e3553be5d6d743a666
  
      Width: 320
  
      Height: 240
  
      Depth: 24
  
      Frame rate: 15/1
  
      Pixel aspect ratio: 1/1
  
      Interlaced: false
  
      Bitrate: 0
  
      Max bitrate: 0
  
  
  
  Properties:
  
    Duration: 0:01:45.505000000
  
    Seekable: yes
  
    Live: no
  
    Tags:
  
        视频编码: H.264 (High Profile)

• Revision 33515 : Erreur dans la requête

  4 décembre 2009, par kent1@… — Log

  Erreur dans la requête