[alsa-devel] left/right bleed or crossover
howdy at cardinalpeak.com
Wed Jul 4 01:02:49 CEST 2007
Takashi Iwai wrote:
> Howdy Pierce wrote:
>> I'm encountering the following problem on Fedora Core 6 running on a Dell
>> Optiplex 745. This is a pretty vanilla computer with an ICH8 chipset and
>> integrated AD1983 sound capabilities.
>> I have wired up a funky line-input cable so that I have completely
>> separate audio sources playing on the left and right inputs.
>> When I either play these through to the speaker output directly (using
>> alsamixer), or record the audio using arecord, the result is that there
>> is a slight bit of bleeding or crossover, so I can faintly hear the left
>> input on the right channel, and vice versa. If I record a wav file and
>> then play it on another computer, the left/right bleeding follows the wav
>> file, so it seems that the problem is in the capture process somehow.
>> When I install Windows XP onto the same machine, the problem disappears,
>> so I can rule out hardware errors.
>> The application I'm working on relies on being able to reliably capture
>> the right and left channels of audio independently. Since the problem
>> can be seen using the standard arecord/aplay tools, though, I don't think
>> it's my code.
>> I've tried all the possible combinations inside alsamixer, and I don't
>> think there's anything I've messed up there.
> To investigate where the problem exists, try to use "hw" PCM first
> without alsa-lib plugins. If the problem still remains, it's in the
> driver (that I don't expect since your codec dump looks sane to me).
Thanks for the response.
I assume you want me to record something with
The problem still exists with that command line. Where do I need to look
next -- the kernel driver? Any theories as to what might be happening here?
Has anyone seen something similar before, perhaps on other hardware?
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