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what is the definition of "Mono Output" in pulseaudio ?

My three other sound cards does support mono playback and mono capture

The system setting/sound in gnome session allow me to select "mono duplex" but when it does not allow me to select "mono output + mono input" in unity session.

That sounds like the known bug I was working on yesterday.

Although those three sound cards (au8830, emu10k1 and ymfpci) support mono playback and capture.

None of them use the AC97 "Master Mono" pin for output.

gnome speaker-test show only one speaker

"Master Mono Playback Volume" was also removed from emu10k1 driver but still exist in au8830 and ymfpci driver

There is no "mono" volume control for capture volume.

There are "LFE on mono" in unity settings/sound in ubuntu 12.04 for au8830 and ymfpci which still have "Master Mono Playback Volume" but "LFE on mono" is not exist in gnome settings/sound Fedora 17 Live CD

Also My Creative 4.1 speaker set only have green and black jacks (Surround40) supported by emu10k1 and au8830

Can anyone explain "Analog Mono Output" and "surround41" in pulseaudio ?