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• FFmpeg - convert 2 audio tracks from video to 5.1 audio, (play video with different languages to different devices) [closed]

  10 février, par Sandre

  How to watch a movie with one language playing through the speakers and another through the headphones ?

  


  Disclaimer : I know nothing about audio conversion, and don't want to study ffmpeg. I spend a few hours searching how to do, actually much more than I want. I found a bunch of questions from different people and not a single working solution, so I made a clunky but working solution. If someone helps me make it more elegant, I'll be happy. If my question just gets downvoted like most ffmpeg newbie questions, it probably deserves it. And I hope my question can help people who want enjoy video with 2 different languages.

  


  A clumsy but working solution.

  


  


  1. Setup Aggregate Audio Device to play 2 channels of 5.1 through speakers and 2 through bluetooth headphones. (On screenshot Audio MIDI Setup for MacOS)


     


  


  2. Use ffmpeg to convert 2 audio tracks into 5.1 audio.

     


  


  3. Play video with new external audio track.

     


  


  


  # print list of channels
ffprobe INPUT.mkv 2>&1 >/dev/null | grep Stream

--- sample output ---
    Stream #0:0(eng): Video: h264 (High), yuv420p(progressive), 1280x544, SAR 1:1 DAR 40:17, 23.98 fps, 23.98 tbr, 1k tbn (default)
    Stream #0:1(rus): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s (default)
    Stream #0:2(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 640 kb/s

# extract audio
ffmpeg -i INPUT.mkv -map 0:1 -acodec copy ru.ac3
ffmpeg -i INPUT.mkv -map 0:2 -acodec copy en.ac3

# extract only front_center channel from 5.1 - speach
ffmpeg -i en.ac3 -filter_complex "channelsplit=channel_layout=5.1:channels=FC[center]" -map "[center]" en_front_center.wav
ffmpeg -i ru.ac3 -filter_complex "channelsplit=channel_layout=5.1:channels=FC[center]" -map "[center]" ru_front_center.wav

# join to 5.1
ffmpeg -i en_front_center.wav -i ru_front_center.wav -filter_complex "[0:a][0:a][0:a][0:a][1:a][1:a]join=inputs=6:channel_layout=5.1[a]" -map "[a]" output.wav


  


  Is it possible to avoid re-encoding the audio and copying the same channel many times to reduce the file size ?

  


• How do Iuse FFMPEG API to add AV_CODEC_ID_ASS stream to my MPEGTS video format

  31 juillet 2020, par Meir Ivry

  I want to add an ASS/SSA subtitle stream to my video format using FFMPEG API.

  


  The specification for that format is in the following link :
ASS file format specification
(http://www.tcax.org/docs/ass-specs.htm)

  


  I know how to that with video, where it compirsed of the following steps

  


  

  1. get the desired AVCodec

  


  2. create new AVStream

  


  3. create new AVCodecContext

  


  4. create the proper AVFrame for each raw video frame.

  


  5. use avcodec_send_frame to encode frame

  


  6. use avcodec_receive_packet to get the frame packets

  


  7. use av_interleaved_write_frame to write the packets

  


  


  My question is the same procedure applies to subtitles and, if so, how do I initialize the AVFrame ?
Moreover, is there more to know other than that ?

  


  Thanks.

  


• Audio Video Editing in Python : How to do it ? [on hold]

  12 mai 2019, par DoakCode

  Does anyone know how to do it ? It’s a bit more complex then then the usual docs I’ve read, so I don’t know where to start and I’d appreciate someone leading me to the right docs or the right path.

  The software should be doing following :

  1. Taking a background picture and making it blurred -> The background
  2. In the front should be :
     1. A picture
     2. Text
     3. A progressing timer (which displays the current status of the video)
  3. Last, but not least, audio should be added to the video or vice versa as the video is supposed to end when the audio ends to round things up.

  As this all is pretty complex editing for a python programme, I don’t know which library(ies) to use.. If someone has a solution / idea please reply !