Arch Linux

bnolsen

Member

Registered: 2008-12-10

Posts: 64

Split input audio into 2 streams?

I was wondering where to start looking to do the following:

With "line in" plugged into the sound card copy to 2 streams

- make a recording at 16bit mono 11025
- have another application process simultaneously do processing at 16bit stereo 48000

I might be able to live with replicating the line in at 16bit/mono/11025 for both purposes.

What terms do I search for and where do I start looking to even do this?

Thanks!

ngoonee

Forum Fellow

From: Between Thailand and Singapore

Registered: 2009-03-17

Posts: 7,362

Re: Split input audio into 2 streams?

What application and what process?

Sounds like you want a sound server like JACK, which most good audio apps are designed to connect to. Pulseaudio is another option.

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bnolsen

Member

Registered: 2008-12-10

Posts: 64

Re: Split input audio into 2 streams?

Any audio recorder will do (mostly use audacity).
Using mumble for transmitting.

Both of these are pretty flexible for audio inputs.

Any hint as to what i need to search for ?

skottish

Forum Fellow

From: Here

Registered: 2006-06-16

Posts: 7,942

Re: Split input audio into 2 streams?

FFmpeg can do it, but I can't remember off the top of my head what needs to be done to set up capturing from the audio device. There's a lot of information in the FFmpeg man page.

As an example of handling the output, I'll just assume some audio file coming in and the two that you wanted out as wav files:

ffmpeg -i <some_input> -ac 2 -ar 48000 first_track.wav -ac 1 -ar 11025 second_track.wav

bnolsen

Member

Registered: 2008-12-10

Posts: 64

Re: Split input audio into 2 streams?

Has to be real time for the one stream.  In the future I'd like to icecast...do that with low bitrate speex and then save a much better quality copy for archival.  Considering how much bandwidth I'm seeing taken with mumble it makes me wonder if broadcasting 24kbps mp3 would be more efficient.

I *could* do the above all with hardware...just hop the sound card audio out into the line of of a usb audio device and deal with it that way.

skottish

Forum Fellow

From: Here

Registered: 2006-06-16

Posts: 7,942

Re: Split input audio into 2 streams?

Has to be real time for the one stream.  In the future I'd like to icecast...do that with low bitrate speex and then save a much better quality copy for archival.  Considering how much bandwidth I'm seeing taken with mumble it makes me wonder if broadcasting 24kbps mp3 would be more efficient.

I *could* do the above all with hardware...just hop the sound card audio out into the line of of a usb audio device and deal with it that way.

FFmpeg will do it in real time. The example above was only for the outputs. As I said before, I simply can't remember what the setup is like to capture the audio, so I just used a local file for the demonstration.