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• Converting DTS to AAC with ffmpeg shifts spoken audio to the right

  18 août 2018, par Giuseppe

  I am using ffmpeg to convert mkv movies to mp4, like so :

  $ ffmpeg -i source.mkv -c:v copy -c:a aac destination.mp4

  By doing this, the audio stream gets converted from the original DTS :

  Stream #0:1: Audio: dts (DTS), 48000 Hz, 5.1(side), fltp, 1536 kb/s (default)

  To AAC :

  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 394 kb/s (default)

  The resulting file plays just fine, except that the spoken audio (what I am assuming would be sent to the central channel in a 5.1 configuration) sounds clearly shifted to the right, when listening through the MacBook’s built-in speakers or my stereo headphones. Note that music and other sound effects appear unaffected, properly balanced. Also note that I have been able to reproduce this behavior with a variety of source files.

  Here’s ffmpeg’s banner :

  ffmpeg version 4.0.2 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.0.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  
    libavutil      56. 14.100 / 56. 14.100
  
    libavcodec     58. 18.100 / 58. 18.100
  
    libavformat    58. 12.100 / 58. 12.100
  
    libavdevice    58.  3.100 / 58.  3.100
  
    libavfilter     7. 16.100 /  7. 16.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  1.100 /  5.  1.100
  
    libswresample   3.  1.100 /  3.  1.100
  
    libpostproc    55.  1.100 / 55.  1.100

• Getting 'av_interleaved_write_frame() : Broken pipe' error

  2 juillet 2016, par Poornan

  I am trying this blog post.I am new to python, numpy as well as FFMPEG. I could not figure out what causes this issue.

  http://zulko.github.io/blog/2013/09/27/read-and-write-video-frames-in-python-using-ffmpeg/

  here is the code :

  import subprocess as sp
  
  import numpy
  
  
  
  print ("Hello World!");
  
  FFMPEG_BIN = "ffmpeg" # on Linux ans Mac OS
  
  #FFMPEG_BIN = "ffmpeg.exe" # on Windows
  
  
  
  command = [ FFMPEG_BIN,
  
              '-i', '/Users/eananthaneshan/Movies/myvideo.mp4',
  
              '-f', 'image2pipe',
  
              '-pix_fmt', 'yuv444p',
  
              '-s', '420x360',
  
              '-r', '24',
  
              '-vcodec', 'h264', '-']
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=-1)
  
  
  
  # read 420*360*3 bytes (= 1 frame)
  
  raw_image = pipe.stdout.read(420*360*3)
  
  # transform the byte read into a numpy array
  
  image =  numpy.fromstring(raw_image, dtype='uint8')
  
  image = image.reshape((360,420,3)   )
  
  # throw away the data in the pipe's buffer.
  
  pipe.stdout.flush()

  This is the output :

  ffmpeg version 2.8 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with Apple LLVM version 7.0.0 (clang-700.0.72)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.8 --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-libfreetype --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libass --enable-ffplay --enable-libspeex --enable-libschroedinger --enable-libfdk-aac --enable-libopus --enable-frei0r --enable-libopenjpeg --disable-decoder=jpeg2000 --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.2_1/include/openjpeg-1.5 ' --enable-nonfree --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
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/eananthaneshan/Movies/myvideo.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 1
  
      compatible_brands: isom
  
      creation_time   : 2014-04-07 02:02:31
  
    Duration: 01:00:10.03, start: 0.000000, bitrate: 1024 kb/s
  
      Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 111 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-04-07 02:02:31
  
        handler_name    : GPAC ISO Audio Handler
  
      Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/unknown/unknown), 720x404, 909 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)
  
      Metadata:
  
        creation_time   : 2014-04-07 01:14:58
  
        handler_name    : L-SMASH Video Media Handler
  
        encoder         : AVC Coding
  
  Output #0, image2pipe, to 'pipe:':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 1
  
      compatible_brands: isom
  
      encoder         : Lavf56.40.101
  
      Stream #0:0(und): Video: rawvideo (444P / 0x50343434), yuv444p, 420x360, q=2-31, 200 kb/s, 23.98 fps, 23.98 tbn, 23.98 tbc (default)
  
      Metadata:
  
        creation_time   : 2014-04-07 01:14:58
  
        handler_name    : L-SMASH Video Media Handler
  
        encoder         : Lavc56.60.100 rawvideo
  
  Stream mapping:
  
    Stream #0:1 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Press [q] to stop, [?] for help
  
  av_interleaved_write_frame(): Broken pipe
  
  frame=    2 fps=0.0 q=-0.0 Lsize=     886kB time=00:00:00.08 bitrate=87003.8kbits/s    
  
  video:886kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
  
  Conversion failed!

• MPEG-4 and alpha transparency - the ongoing saga

  6 décembre 2022, par OrangeDog

  I'd like to reach some sort of definitive answer for the following questions :

  



  

  1. Is alpha transparency supported in MPEG-4-based codecs ?

  


  2. Is there any way to be reasonably certain that there is no alpha-channel from the output of ffprobe ?

  


  



  Some links I've found on the subject :

  



  

  • https://stackoverflow.com/a/5057631/476716

  


  



  


  Also, transparent alpha layers, an optional part of the H.264 specification, are now supported in H.264-based QuickTime movies.

  


  



  

  • http://software.intel.com/en-us/articles/alpha-channel-support-in-the-h264-decoder-in-ipp/

  


  



  


  The support for alpha channel in the H.264 decoder is now available in Intel® Integrated Performance Primitives 6.0 version.

  


  



  

  • http://forums.creativecow.net/readpost/335/30475

  


  



  


  The MPEG4 Simple Studio Profile supports auxiliary channels, which could be used for alpha or depth — and presumably even displacement, motion vectors, normals, etc.

  


  



  However, I've never seen a concrete example, or indeed any details on how you use these announced features.