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• Script that will use ffmpeg to add AAC 2.0 audio streams to videos

  9 juillet 2018, par jsr

  I need to cast some videos to my Chromecast that only allows AAC audio. I have some video files and I am continuously adding more. They all have AC3 audio. The ideal would be to have a script that uses ffmpeg/ffprobe to add (not replace) an AAC stream converting the AC3 stream. The script should be looking in a path (and all the subfolders) every night for movies without AAC 2.0 streams.

  The container should me mkv. Can anyone help me getting started ? I’m not very into python yet so I don’t know where to start, but I do understand the coding. Help is much appreciated !

• When I append a silent audio (mp3) to an existing list of audio it garbles the final audio ?

  6 février 2020, par Marie

  After several hours I have narrowed down the issue with the garbled audio to be the 2-seconds silence audio mp3 I am appending (I think I had produced it once with Wavelab)

  However, I tried using ffmpeg according to a post to produce a similar 2 seconds audio but it too will corrupt/garble/chop voice in the final concatenation of audio files.

  ffmpeg -f lavfi -i anullsrc=r=44100:cl=mono -t 2 -q:a 9 -acodec libmp3lame SILENCE_2sec.MP3

  I typically will have several audio files to concatenate together but for simplicity I have able to narrow it to a couple of files simplifying to the following script. A simple Windows batch file you should be able to use and reproduce the issue at your end.

  rem 
  
  rem  
  
  SET EXE="S:\_BINS\FFmpeg 4.2.1 20200112\bin\ffmpeg.exe"
  
  
  
  SET ROOTPATH=.\
  
  
  
  SET IN_FILE="%ROOTPATH%MyList.txt"
  
  
  
  ECHO file '%ROOTPATH%HELLO.mp3' > MyList.txt
  
  ECHO file 'SILENCE_2sec.MP3' >> MyList.txt
  
  
  
  SET OPTIONS= -f concat -safe 0 -i  %IN_FILE%  -c copy -y
  
  
  
  SET OUT_FILE="%ROOTPATH%CONCATENATED_AUDIO_2.MP3"
  
  
  
  SET INFO_FILE="INFO.TXT"
  
  
  
  %EXE% %OPTIONS%  %OUT_FILE% 1> %INFO_FILE% 2>&1 
  
  
  
  ECHO ======================== >> %INFO_FILE%
  
  ECHO IN_FILE=%IN_FILE%  >> %INFO_FILE% 
  
  ECHO EXE=%EXE%  >> %INFO_FILE% 
  
  ECHO OPTIONS=%OPTIONS%  >> %INFO_FILE% 
  
  ECHO ======================== >> %INFO_FILE%

  Here is the console info output from the ffmpeg, let me know if you need other output include ones from ffprobe

  ffmpeg version git-2020-01-10-3d894db Copyright (c) 2000-2020 the FFmpeg developers
  
    built with gcc 9.2.1 (GCC) 20191125
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  
    libavutil      56. 38.100 / 56. 38.100
  
    libavcodec     58. 65.103 / 58. 65.103
  
    libavformat    58. 35.101 / 58. 35.101
  
    libavdevice    58.  9.103 / 58.  9.103
  
    libavfilter     7. 70.101 /  7. 70.101
  
    libswscale      5.  6.100 /  5.  6.100
  
    libswresample   3.  6.100 /  3.  6.100
  
    libpostproc    55.  6.100 / 55.  6.100
  
  [mp3 @ 000000000036af80] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, concat, from '.\MyList.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 32 kb/s
  
      Stream #0:0: Audio: mp3, 24000 Hz, mono, fltp, 32 kb/s
  
  Output #0, mp3, to '.\CONCATENATED_AUDIO_2.MP3':
  
    Metadata:
  
      TSSE            : Lavf58.35.101
  
      Stream #0:0: Audio: mp3, 24000 Hz, mono, fltp, 32 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mp3 @ 0000000000372d00] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 17280 >= 17255
  
  size=      11kB time=00:00:02.73 bitrate=  33.2kbits/s speed=2.73e+03x    
  
  video:0kB audio:11kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.137446%
  
  ======================== 
  
  IN_FILE=".\MyList.txt"   
  
  EXE="S:\_BINS\FFmpeg 4.2.1 20200112\bin\ffmpeg.exe"   
  
  OPTIONS= -f concat -safe 0 -i  ".\MyList.txt"  -c copy -y   
  
  ========================  

  I believe I am running FFmpeg 4.2.1, recently installed (20200112)

  You may produce the HELLO.mp3 by saving the following link

  https://translate.google.com.vn/translate_tts?en=UTF-8&q=Hello+&tl=en&client=tw-ob

  FYI, I am still a novice of ffmpeg and using it more like a black box with the help I received in this very super forum.
  Please be as explicit as you can with command line options on how I can fix this issue.
  Thank you.

  Additional Hints Debugging :

  If I append more files after the silence audio it seems that the silence audio impacts (garbles, chops) the previous audio.
  You may try the following for the list of audio files input.

  ECHO file '%ROOTPATH%HELLO.mp3' > MyList.txt
  
  ECHO file 'SILENCE_2sec.MP3' >> MyList.txt
  
  ECHO file '%ROOTPATH%HELLO.mp3' >> MyList.txt
  
  ECHO file '%ROOTPATH%HELLO.mp3' >> MyList.txt

  I typically add one or more silence file to derive a post silence effect after the actual audio. That’s my current logic. However if you have an alternative to appending a silence in the process of concatenating several audio files or appending x-seconds silence to an existing audio file. I can use that method as well from my coding.

  Thank you.

• ffmpeg screencasting with webcam

  6 septembre 2017, par curiouser

  I want to use the screen view of the computer in real-time for a fake webcam. I did the video action on the bottom. But the frames like the video (2.34) are forming on top of each other. How can I solve this problem.

  https://www.youtube.com/watch?v=6AZRiW3hHrw

  Load the module
  
  sudo modprobe v4l2loopback exclusive_caps=1
  
  
  
  Find the dummy device
  
  v4l2-ctl --list-devices
  
  
  
  Start the virtual-webcam (change "/dev/video1" to reflect your system)
  
  ffmpeg -f x11grab -r 15 -s 1920x1080 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video1