Status of USB audio support in OSS v4 on Linux ?

Discussion:

Wannabe Tsotsi

2011-10-04 21:05:06 UTC

Hi,

I've read that, on Linux, USB audio playback is experimental and record is not implemented.

I also read that changing the alt setting sometimes works for input !

Based on the above comments from the forums, it appears this is more likely a dev problem than a configuration issue.

My own testing with a USB headset shows playback working while record does not.

rec_callback() len == 0
oss usbaudio: Audio input timed out on device 13.

USB record and playback code in build-2005 and oss-devel head seem pretty comprehensive.

So, what is the current status of USB audio on Linux ?

Could someone outline what needs to be implemented to get input working, is there any work in progress ?

I don't want to step on any toes, but with some guidance I'm willing to program, debug, do whatever I can to help.

Thanks.

Hannu Savolainen

2011-10-06 19:22:54 UTC

Permalink

Hi,

The problem with USB audio is that it needs to work both with Linux and
Solaris which have rather different USB subsystems. Since the funding
for OSS came from Sun keeping the Solaris code functional has been the
priority.

USB audio recording worked under Linux until (around) 2.6.17 where the
semantics of the USB framework changed. The code in
setup/Linux/oss/build/usb_wrapper.inc needs to be modified in way or
another but I didnt manage to figure out how.

Best regards,

Hannu
--

Post by Wannabe Tsotsi
Hi,
I've read that, on Linux, USB audio playback is experimental and record is not implemented.
I also read that changing the alt setting sometimes works for input !
Based on the above comments from the forums, it appears this is more
likely a dev problem than a configuration issue.
My own testing with a USB headset shows playback working while record does not.
rec_callback() len == 0
oss usbaudio: Audio input timed out on device 13.
USB record and playback code in build-2005 and oss-devel head seem pretty comprehensive.
So, what is the current status of USB audio on Linux ?
Could someone outline what needs to be implemented to get input working,
is there any work in progress ?
I don't want to step on any toes, but with some guidance I'm willing to
program, debug, do whatever I can to help.
Thanks.
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oss-devel mailing list
http://mailman.opensound.com/mailman/listinfo/oss-devel

Wannabe Tsotsi

2011-10-07 15:00:13 UTC

Permalink

Thanks very much Hannu, this is a really useful head start, I now know where to focus my attention and aim to do so.

________________________________
From: Hannu Savolainen <***@opensound.com>
To: oss-***@mailman.opensound.com
Sent: Thursday, 6 October 2011, 20:22
Subject: Re: [oss-devel] Status of USB audio support in OSS v4 on Linux ?

Hi,

The problem with USB audio is that it needs to work both with Linux and
Solaris which have rather different USB subsystems. Since the funding
for OSS came from Sun keeping the Solaris code functional has been the
priority.

USB audio recording worked under Linux until (around) 2.6.17 where the
semantics of the USB framework changed. The code in
setup/Linux/oss/build/usb_wrapper.inc needs to be modified in way or
another but I didnt manage to figure out how.

Best regards,

Hannu
--