Audio loopback in linux kernel? [try...]

Stuart Levy slevy at ncsa.uiuc.edu
Thu Apr 6 23:45:21 CDT 2000


I've just built a linux-glibc2 (Red Hat 6.1) rat 4.2.1 with some audio
driver mods which might help, maybe, for both Karen's and Richard's cases.

There's a tarball (just tar not rpm) at
    http://niri.ncsa.uiuc.edu/slevy/rats/rat-4.2.1-linux86-glibc2.tar.gz

This contains auddev_oss mods which
   - made our Creative SBLive card (non-Platinum I think) work
	using the Creative-supplied open-source driver.

	We didn't use ossmix to initialize the SBLive mixer, instead
	editing the setup-mixer script to invoke "aumix" with
	corresponding options.  If ossmix actually refuses to work
	rather than just complaining, you (either Richard or Karen)
	might try aumix.

   - might handle AC97-compliance that Bob suggests as
	causing the problems Karen saw with previous audio hardware.
	Now rat adjusts IGAIN if the driver says it exists,
	otherwise adjusts LINE.
	I haven't been able to test this except on a Dell with built-in
	CS423x audio hardware (whose audio in/out I can't reach...).

Details are in "rat-4.2.1.patch" inside the tarball -- this is what I'd
like to send to UCL if anybody gets a chance to try these and they're OK.

Also in same directory:

   http://niri.ncsa.uiuc.edu/slevy/rats/rat-4.2.1-sgi.tar.gz
	Irix n32 binaries for rat 4.2.1, compiled under Irix 6.3

   http://niri.ncsa.uiuc.edu/slevy/rats/rat-4.2.1.patch
	Source patch alone (with descriptions of what it's supposed to do)

Above binaries do include the "-N"-option patch Bob mentioned earlier,
though the patch file doesn't mention it.

Flakiness: With both the Irix and Linux versions, I've had a few crashes
where the rat...-media module reports that it "Can't send mbus message".
Seemed to happen when I was switching input sources and maybe when
ctrl-Z'ing the programs; not sure.

If anyone tries these, please let me know what you find.

   Stuart Levy



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