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• How to record video and audio with ffmpeg and pipe only audio to python process

  9 juin 2023, par urico12

  I have an ffmpeg command recording video and audio as one output and
I'm trying to add a second output to pipe out only the raw audio to python so that I can run additional processing on the audio chunks.

  


  from subprocess import Popen, PIPE, STDOUT

record_audio_video_command = f"ffmpeg -i small_bunny_1080p_60fps.mp4 \ 
                             -vcodec libx264 output.mp4 -f s16le pipe:1"

record_command = Popen(record_audio_video_command, 
                        shell=True, 
                        stdout=PIPE, 
                        stderr=STDOUT)

f = open("output.txt", "w")
data = record_command.stdout.read(320)
f.write(str(data))
while len(data) > 0:
    data = record_command.stdout.read(320)
    f.write(str(data))


  


  Is there a way to have ffmpeg pipe out only the raw audio bytes as one output, while still recording video and audio as the other output ?

  


• Add a 2nd audio stream using ffmpeg so you can switch audio streams on iOS ?

  26 décembre 2019, par Tony M

  I have an m.mp4 with English audio and want to add a second audio stream in Italian so that I can play either language using the iPhone. When I used this command :

  ffmpeg -i m.mp4 -i ita.mp3 -c copy -map 0 -map 1 out.mp4 

  The output from ffmpeg -i out.mp4 (see below) shows that a new audio stream is added, and I can switch between audio streams using the VLC player. Yet when I transfer the video to the TV app and play it on either MacOS or iOS it only plays the original English and I see no options to play other languages.

  How do I get it to be able to switch between either audio on iOS ?

  Here is the output from ffmpeg -i out.mp4:

      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 400x300 [SAR 1:1 DAR 4:3], q=2-31, 482 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 24k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 102 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Stream #0:2: Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s
  
      Metadata:
  
        encoder         : LAME3.100
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
    Stream #1:0 -> #0:2 (copy)

• Extract all audio streams from video into seperate audio files using ffmpeg and python

  15 novembre 2020, par Insberr

  I'm trying to extract all the audio streams/tracks (whatever you wanna call them) from a video and save each one to a separate audio file using python and ffmpeg.
  
The problem is, I would need to know how many audio streams there are and I don't want to have to enter the number of streams the file has manually nor do I want to run a ffmpeg command for each file to figure it out.
  
Is there a way for the program to figure out how many streams there are so I can extract each stream to a separate file ?

  


  Here is a snippet of the code
inputFiles is a list of directories to each video file being inputted
  
_dir_in is the directory that all the input files are in
  
_dir_out is the directory all the files outputted by the code are placed

  


  for video in inputFiles:
    number_of_audio_streams = 0 # this is where I need to know how many audio streams there are
    for i in range(number_of_audio_stremas):
        subprocess.call(f'ffmpeg -i {_dir_in}/{video} -map 0:a:{str(i)} {_dir_out}/audio/{video}-{str(i)}.m4a')