Red Hat Bugzilla – Bug 471864
Pulseaudio only uses 2 channels on a multichannel sound device
Last modified: 2008-12-18 09:09:29 EST
Description of problem:
Pulseaudio only uses the front 2 speakers on a SB Live (EMU10K1) sound card which supports 4 speakers. This is not only the default setting, but there is no way to fix it without manually hacking the config files.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Install Rawhide on machine with multichannel sound card
2. Try playing sound through rear speakers
3. Observe silence
Pulseaudio only sees 2 channels on the hardware, even though "aplay -L" clearly lists a "surround40" subdevice with 4 channels.
Pulseaudio should detect the existence of a multichannel device and enable the extra channels, or at the very least allow the user to select the appropriate subdevice.
The work-around is to add "default-sample-channels = 4" to /etc/pulse/daemon.conf, but this changes the number of channels seen on all the other sound cards in the machine too, which may not be what you want.
This bug appears to have been reported against 'rawhide' during the Fedora 10 development cycle.
Changing version to '10'.
More information and reason for this action is here:
Unfortunately there is now way to magically detect what kind of speakers you have actually connected to your sound cards. We can't know if it is 2.0, 3.1, 4.0, 5.0, 5.1, 7.0, 7.1 or any other weird setup. That means you will always have to configure something manually. Right now this is done via editing configuration files. In the future we will allow that via a simple UI.
This quite clearly is a bug - "upgrading" caused my system went from all my speakers working to only 2 of them working, with no indication as to how to fix it.
Additionally, as I mentioned, the workaround affects *all* the sound cards in the system, which is probably not what you want.
*** This bug has been marked as a duplicate of bug 355161 ***