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• How can I mux a MKV and MKA file and get it to play in a browser ?

  28 juin 2017, par Robert

  I’m using ffmpeg to merge .mkv and .mka files into .mp4 files. My current command looks like this :

  ffmpeg -i video.mkv -i audio.mka output_path.mp4

  The audio and video files are pre-signed urls from Amazon S3. Even on a server with sufficient resources, this process is going very slowly. I’ve researched situations where you can tell ffmpeg to skip re-encoding each frame, but I think that in my situation it actually does need to re-encode each frame.

  I’ve downloaded 2 sample files to my macbook pro and have installed ffmpeg locally via homebrew. When I run the command

  ffmpeg -i video.mkv -i audio.mka -c copy output.mp4

  I get the following output :

  ffmpeg version 3.3.2 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with Apple LLVM version 8.1.0 (clang-802.0.42)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  Input #0, matroska,webm, from '319_audio_1498590673766.mka':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2017-06-27T19:10:58.000000Z
  
    Duration: 00:00:03.53, start: 2.831000, bitrate: 50 kb/s
  
      Stream #0:0(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : Audio
  
  Input #1, matroska,webm, from '319_video_1498590673766.mkv':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2017-06-27T19:10:58.000000Z
  
    Duration: 00:00:03.97, start: 2.851000, bitrate: 224 kb/s
  
      Stream #1:0(eng): Video: vp8, yuv420p(progressive), 640x480, SAR 1:1 DAR 4:3, 30 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        title           : Video
  
  [mp4 @ 0x7fa4f0806800] Could not find tag for codec vp8 in stream #0, codec not currently supported in container
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (copy)
  
    Stream #0:0 -> #0:1 (copy)
  
      Last message repeated 1 times

  So it appears that the specific encodings I’m working with are vp8 videos and opus audio files, which I believe are incompatible with the .mp4 output container. I would appreciate answers that cover ways of optimally merging vp8 and opus into .mp4 output or answers that point me in the direction of output media formats that are both compatible with vp8 & opus and are playable on web and mobile devices so that I can bypass the re-encoding step altogether.

  EDIT :

  Just wanted to provide a benchmark after following LordNeckbeard’s advice :

  4 min 41 second video transcoded locally on my mac
  
  
  
  LordNeckbeard’s approach : 15 mins 55 seconds (955 seconds)
  
  Current approach : 18 mins 49 seconds (1129 seconds)
  
  
  
  18% speed increase

• ffmpeg resample to flac loud clicks/noise

  4 août 2017, par Sjoerd Staal

  I’m using the ffmpeg-api to resample a DSD file to Flac & mp3. I don’t experience any problems with the mp3 resample, but with the flac resample there is always a loud click at the end of a track.

  I’m using the FFMpeg API which outputs the following command in command line :

  ffmpeg -i input.dsf -ar 192000 -acodec flac output.flac

  Output :

  ffmpeg version 2.8.5 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with Apple LLVM version 7.0.2 (clang-700.1.81)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.8.5 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-vda
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [mjpeg @ 0x7fe617809000] Changeing bps to 8
  
  [dsf @ 0x7fe617000000] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, dsf, from 'input.dsf':
  
    Metadata:
  
      title           : Bach Brandenburg no. 6 - Allegro
  
      artist          : Florilegium
  
      album           : Brandenburg Concertos
  
      track           : 3
  
      Tool Version    : 18.0.212
  
      genre           : Classical
  
      composer        : Bach
  
      Catalog #       : 35914
  
      Format          : DSD
  
      ISRC            : NLA460912792
  
      Label           : Channel Classics
  
      Tool Name       : Media Center
  
      date            : 2014
  
    Duration: 00:06:00.31, bitrate: 5644 kb/s
  
      Stream #0:0: Audio: dsd_lsbf_planar, 352800 Hz, stereo, fltp, 5644 kb/s
  
      Stream #0:1: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 1429x1417 [SAR 300:300 DAR 1429:1417], 90k tbr, 90k tbn, 90k tbc
  
      Metadata:
  
        title           : Picture
  
        comment         : Cover (front)
  
  [flac @ 0x7fe617122000] encoding as 24 bits-per-sample
  
  Output #0, flac, to 'output.flac':
  
    Metadata:
  
      title           : Bach Brandenburg no. 6 - Allegro
  
      artist          : Florilegium
  
      album           : Brandenburg Concertos
  
      TRACKNUMBER     : 3
  
      Tool Version    : 18.0.212
  
      genre           : Classical
  
      composer        : Bach
  
      Catalog #       : 35914
  
      Format          : DSD
  
      ISRC            : NLA460912792
  
      Label           : Channel Classics
  
      Tool Name       : Media Center
  
      date            : 2014
  
      encoder         : Lavf56.40.101
  
      Stream #0:0: Audio: flac, 192000 Hz, stereo, s32 (24 bit), 128 kb/s
  
      Metadata:
  
        encoder         : Lavc56.60.100 flac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (dsd_lsbf_planar (native) -> flac (native))
  
  Press [q] to stop, [?] for help
  
  size=  306541kB time=00:05:58.10 bitrate=7012.3kbits/s    
  
  video:0kB audio:306532kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.002733%

• ffmpeg called from python random failure

  9 juillet 2017, par Jim Weisbin

  Python 2.7.1 on Mac OS X 10.12.5, ffmpeg 3.3.2 (installed with Brew).

  ffmpeg is called in a loop though thousands of Apple Lossless files, converting to mp3 and tagging.

  thecall = '/usr/local/bin/ffmpeg -hide_banner -loglevel error -i ' + <path to="to" m4a="m4a" file="file"> + ' -i ' + <path to="to" artwork="artwork"> + ' -map 0:0 -map 1:0 -id3v2_version 3 -map_metadata -1 -metadata album="xxx" -metadata artist="xxx" -metadata comment="Cover (Front)" -f mp3 -b:a 128K ' + <path to="to" mp3file="mp3file">'
  
  </path></path></path>

  os.system(thecall)

  this works perfectly from the command line, and also works from Python most of the time, but randomly fails with the message

  [alac @ 0x7fc888858800] invalid samples per frame : 0
  Error while decoding stream #0:0 : Invalid data found when processing input

  What’s strange is that on the files it failed on, if I run it from the command line it succeeds. I tried putting in time.sleep(5) but no change. And the failures are not always on the same file, so it seems like it’s a memory or threading issue. I also tried calling with subprocess() instead, no change.

  Any help would be appreciated.