Re: [ecasound] ecamegapedal, full-duplex, usb audio

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Subject: Re: [ecasound] ecamegapedal, full-duplex, usb audio
From: Kai Vehmanen (k_AT_eca.cx)
Date: Wed Sep 11 2002 - 01:38:22 EEST


On Mon, 9 Sep 2002, janne halttunen wrote:

> is supported by the driver. Perhaps you could test with ecasound: first
> playback, then recording, and finally playback and recording.

Or if you suspect ecasound (or some other app) is not working, you can do
the following full-duplex test:

1. start a mixer app (for example 'aumix' or 'alsamixer')
    - set recording source to 'mic' (or 'line-in')
    - unmute 'master' and 'pcm'
    - mute 'mic' (or 'line-in')
2. play a mp3 or wav file
    - if nothing comes out, go back to (1) and unmute
      more controls and increase levels until you hear
      some output
    => if ok: output works
3. talk to the mic (or feed data to line-in)
    - you should _not_ hear anything from the speakers
    - if problems, go back to (1)
4. issue "cat </dev/dsp |hexdump"
    - you should see a matrix-ish hexview :) - the numbers
      should react to the mic input
    => if ok: input works
5. issue "cat </dev/dsp >/dev/dsp" and keep on
   talking to the mic
    - you should now hear the mic-in signal
      from the speakers
    => if ok: full-duplex works

... you can do this test with all drivers (OSS/kernel, OSS/commercial, all
ALSA versions w/ OSS-emulation, various driver-specific drivers).

> I am thinking about writing somesort of a test-script for this common
> category of problems. Don't hold your breath, though :)

That would be great! ;)

-- 
 http://www.eca.cx
 Audio software for Linux!

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