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I currently have a wireless USB headset which works ok, but has the typical drawbacks of USB headsets (acts as a separate sound card to the host OS). For that reason I'm considering to get a Pi and use it like this:

  • USB headset on the first USB port
  • simple USB soundcard on the second USB port

That way I could connect the stereo jacks from the USB soundcard to my PC's onboard soundcard and use the USB headset like a "normal" headset. Additionally I could do probably some nice stuff with the GPIOs to connect e.g. a rotary switch for volume adjustment and a mute button.

However, since I don't have a Pi yet I wonder if there'll be a noticable latency with this setup? On the software side I thought about using JACK to make the connection between the two audio devices.

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The USB chip on the Pi is a strange piece of hardware, intented to be used rarely, with some missing features, emulated by the driver. And the ethernet port is actually a USB one. If I understood correctly, you plan to use 3 stereo streams: headset playback and full duplex to the PC. This seems unrealistic, especially if you have some network traffic. There are a bunch of I2S DAC available now, which use the I2S bus instead, but no ADC yet.

As for JACK: situation has improved, some cards work quite well, other produce horrible sound. There is a thread on the Raspberry Forum: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=38&t=33462

NB: if you want to pair 2 soundcards into one, you will have timing issues unless you hack the oscillator of one to drive both. See http://alsa.opensrc.org/TwoCardsAsOne

  • There won't be network traffic so the only thing on the USB ports would be the headset and the soundcard. For the clock timing issue: jackaudio.org/multiple_devices sounds like it's not too hard to get rid of the issues on the software side? – ThiefMaster Nov 4 '13 at 13:53
  • "YMMV". Getting JACK to run with one card is a journey on its own. As far as I know, nobody got multiple streams working succesfully. And I for one am very interested in 4 mono streams in / 2 mono streams out, for a radio application. – M Noit Nov 6 '13 at 10:09

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