[gst-devel] [oss-devel] libgstoss4audio / SNDCTL_MIX_READ

Clive Wright clive_wright at ntlworld.com
Thu May 8 14:57:14 CEST 2008

The recently added gstreamer plugin for OSS4 has problems handling the 
value returned by SNDCTL_MIX_READ for control type MIXT_MONOSLIDER16 
(and I suspect MIXT_MONOSLIDER).

See attached extract of oss4_mixer.log

This appears to be caused by stereo values being returned by 
SNDCTL_MIX_READ for these control types.

The OSS v4 Programmer's guide is not explicit in this situation stating 
only that:

"The current value of the mixer control will be returned in the value 

This is elaborated on in the next section on scaling but does not 
discuss differences between values returned by mono and stereo controls 
(or is this because they are treated identically).

Perhaps this should be filed as a bug report but I am mindful of getting 
into the not uncommon situation where two projects claim that it is the 
other projects responsibility.

A quick fix in the form of a patch for gstreamer-plugins-bad is attached.

Whether this is the correct solution for this problem depends on if the 
values being returned by SNDCTL_MIX_READ are correct. OSS project please 

Kind regards,

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