is oss unable to record on loopback?

OSS specific Solaris discussion (x86/SPARC)

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Joined: Sun Jun 11, 2006 6:23 pm

is oss unable to record on loopback?

Postby solaris_user » Mon Oct 01, 2007 7:02 pm

hello all,
after this non success try:
i'm installing OSS on Solaris 10 8/07, without success again

I doesn't understand why loopback isn't available by default, and i'm searching on the net some docs about it. I found:
but nothing seems to be applicable to last release of OSS, does it?
If i did:
ultra20-henry% ossrecord -s48000 -b16 -c2 -d /dev/dsp0 test.wav
ultra20-henry% ossplay test.wav
i'm hearing nothing...
In vmix.conf, there are 8 entries:

and dev suggested that i set numloops to 1, but i don't know if it is related to a particular entry (vmix1, vmix2, etc...) or if numloops can be set to 2, 3, 4...
Where can i find the description of these variables?
what is the relation beetween these 8 parameters and what i see from ossinfo
ultra20-henry% ossinfo -v
Version info: OSS 4.0 (b1006/200708291218) (0x00040002)
Platform: SunOS/i86pc 5.10 Generic_120012-14 (ultra20)

Number of audio devices: 2
Number of audio engines: 7
Audio devices
/dev/oss/ich0/pcm0 Nvidia nForce4 (device index 0)
Legacy device /dev/dsp0
Modes: IN/OUT
Engine 1: Busy (IN/OUT) label 'VMIX'
Engine 2: Busy (IN/OUT) label 'gnome-settings-'
Engine 3: Available for use
Engine 4: Available for use
Engine 5: Available for use
Engine 6: Available for use

Why only 6 engines? Why Engine 1 and 2 are busy? Is it a problem when i want to record from loopback?

And again, OSS is ready to record from loopback device?

thanks in advance,


Posts: 585
Joined: Fri Sep 12, 2003 6:08 am
Location: Culver City, CA

Postby dev » Wed Oct 03, 2007 7:31 pm

You can enable the loopback device by setting /usr/lib/oss/conf/vmix.conf and set num_loops=1 and restart the drivers by running ossdetect.

You can then look at ossinfo -v and see that you will get /dev/oss/vmix0/loop0 is a loopback recording device.

Now when you play any audio via VMIX you should be able to record it via
ossrecord -s48000 -b16 -c2 -d/dev/oss/vmix0/loop0 test.wav

Dev Mazumdar

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