FFMpeg giving invalid argument error with python subprocess

Question

I am trying to convert a file or microphone stream to 22050 sample rate and change tempo to double. I can do it using terminal with below code;

#ffmpeg -i test.mp3 -af asetrate=44100*0.5,aresample=44100,atempo=2 output.mp3

But i can not run this terminal code with python subprocess. I try many things but every time fail. Generaly i am taking Requested output format 'asetrate' or 'aresample' or 'atempo' is not suitable output format errors. Invalid argument. How can i run it and take a stream with pipe?

song = subprocess.Popen(["ffmpeg.exe", "-i", sys.argv[1], "-f", "asetrate", "22050", "wav", "pipe:1"],
                        stdout=subprocess.PIPE)

llogan · Accepted Answer · 2020-01-23 01:41:55Z

2

Your two commands are different. Try:

song = subprocess.Popen(["ffmpeg", "-i", sys.argv[1], "-af", "asetrate=22050,aresample=44100,atempo=2", "-f", "wav", "pipe:1"],

-af is for audio filter.
-f is to manually set muxer/output format

answered Jan 23, 2020 at 1:41

llogan

137k30 gold badges261 silver badges270 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Emre Erol Over a year ago

Ok it is working. Thanks a lot.. May i ask you a new question? How can i give a live stream microphone input these code? Accualy i want to change sys.argv[1] parameter with pyaudio callback sound data. Can you give an example or tip about this ? @llogan

metatoaster · Accepted Answer · 2020-01-23 01:39:54Z

2

ffmpeg interprets whatever supplied by -af as a single argument that it would then parse internally into separate ones, so splitting them out before passing it via Popen would not achieve the same thing.

The initial example using the terminal should be created using Popen as

subprocess.Popen([
    'ffmpeg', '-i', 'test.mp3', '-af', 'asetrate=44100*0.5,aresample=44100,atempo=2',
    'output.mp3',
])

So for your actual example with pipe, try instead the following:

song = subprocess.Popen(
    ["ffmpeg.exe", "-i", sys.argv[1], "-f", "asetrate=22050,wav", "pipe:1"],
    stdout=subprocess.PIPE
)

You will then need to call song.communicate() to get the output produced by ffmpeg.exe.

answered Jan 23, 2020 at 1:39

metatoaster

19.2k5 gold badges65 silver badges74 bronze badges

2 Comments

Emre Erol Over a year ago

Ok it is working. Thanks a lot.. May i ask you a new question? How can i give a live stream microphone input these code? Accualy i want to change sys.argv[1] parameter with pyaudio callback sound data. Can you give an example or tip about this ?

metatoaster Over a year ago

Probably check to see if pyaudio can output to stdout and then pipe it into ffmpeg.

Collectives™ on Stack Overflow

FFMpeg giving invalid argument error with python subprocess

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related