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Stacking PCI input cards

post #1 of 9
2/12/12 at 12:40am
Thread Starter 

Hey everyone, f!rst p0st!

 

My question is pretty simple, but searching hasn't yielded much. 

Does anyone have experience using multiple PCI sound cards concurrently to capture as many audio channels as possible? I'm trying to get at least 4 inputs per card and up to 4 cards per machine, plus the built in mic & line in.

I'm looking for low-ish latency but quality is not especially important.

 

So far I'm leaning towards PulseAudio on a barebones linux install as a first test, unless you guys have any better suggestions.

 

Thanks!

 

db

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post #2 of 9
2/12/12 at 4:48am
Quote:

Originally Posted by genbeany View Post

 

My question is pretty simple, but searching hasn't yielded much. 

Does anyone have experience using multiple PCI sound cards concurrently to capture as many audio channels as possible? I'm trying to get at least 4 inputs per card and up to 4 cards per machine, plus the built in mic & line in.

I'm looking for low-ish latency but quality is not especially important.

 

So far I'm leaning towards PulseAudio on a barebones linux install as a first test, unless you guys have any better suggestions.

 

It should be possible, although I do not use PulseAudio, only ALSA. But the recording software needs to take into account that the cards will not have exactly the same sample rate, and resample to keep the streams synchronized.

By the way, I think the majority of cards have only 2 channels of input, the line and microphone in tend to share the same ADC.

 

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post #3 of 9
2/12/12 at 4:39pm

Yes, it is a common thing to do in the audio recording circles to provide more I/O for recording.

 

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post #4 of 9
2/12/12 at 7:50pm
Thread Starter 

I don't think matching the sample rates matters for me, as I am not recording the audio - I'm just converting each input directly into independent http streams.

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post #5 of 9
2/12/12 at 8:22pm

in order to gang them together into a composite device; matching the sample rates very much DOES matter

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post #6 of 9
2/12/12 at 8:29pm
Thread Starter 

Ah I will see to that then. I was assuming it was just for temporal consistency when recording the multiple channels together.

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post #7 of 9
2/12/12 at 9:06pm

Hmm... all from external sources ... can't you do all w/o soundcards by using stored source files or is it live sources in question?

 

jiiteepee

 

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post #8 of 9
2/13/12 at 9:38pm
Thread Starter 

Yeah it's all from live, external, analog sources. Thing is I don't need stereo sound, so I was thinking of inputting two independent sources into each stereo input via RCA -> 1/8th inch adapters for each soundcard input, and then separating them in software, finally assigning each left and right channel to a different URL stream... Any reason why that would be impossible?

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post #9 of 9
2/14/12 at 1:40am
Quote:
Originally Posted by genbeany View Post

Any reason why that would be impossible?


It should work. In fact, if you do not need the streams to be synchronized, then even the different sample rates of the cards may not be an issue.

 

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