[gstreamer-bugs] [Bug 567690] New: Problems with OSS mixer code

[GStreamer (bugzilla.gnome.org)]

If you have any questions why you received this email, please see the text at
the end of this email. Replies to this email are NOT read, please see the text
at the end of this email. You can add comments to this bug at:
  http://bugzilla.gnome.org/show_bug.cgi?id=567690

  GStreamer | gst-plugins-good | Ver: 0.10.x
           Summary: Problems with OSS mixer code
           Product: GStreamer
           Version: 0.10.x
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: brian.cameron at sun.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: 2.25/2.26
   GNOME milestone: Unspecified


I notice that the volume control using the OSSv3 mixer plugin in
gst-plugins-good 
is using the SNDCTL_DSP_PLAYVOL.  That's *not* a good thing to do in a mixer 
application.  That ioctl is supposed to adjust the play volume associated with
an 
application.  It affects that applications input into the audio mixer.  It does 
*not* adjust the system volume.

In OSS 3.x the better solution is to pick on one of the SOUND_MIXER_xxx ioctls 
--  probably SOUND_MIXER_READ_VOLME (and WRITE of course), _OGAIN, or _PCM 
(perhaps in that order). 

In other implementations of OSS, the SNDCTL_SET_PLAYVOL is probably implemented
in terms of those other ioctls.


-- 
See http://bugzilla.gnome.org/page.cgi?id=email.html for more info about why you received
this email, why you can't respond via email, how to stop receiving
emails (or reduce the number you receive), and how to contact someone
if you are having problems with the system.

You can add comments to this bug at http://bugzilla.gnome.org/show_bug.cgi?id=567690.