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Re: PulseAudio



 ❦ 18 juillet 2013 01:00 CEST, Wouter Verhelst <wouter@debian.org> :

>> Alsa is a completely different layer in the sound stack. It doesn't even
>> make sense to compare these two.
>
> They're both APIs that applications can use to produce audio. What do
> you mean, it doesn't make sense?
>
> Of course they're not the same thing; I get that. That's not what I'm
> saying. But as far as "producing audio" is concerned, they can both do
> that.

To make Alsa work with some 7.1 setup through HDMI:

pcm.hdmi-remap {
       type route
       slave.pcm hdmi
       ttable.0.0 1
       ttable.1.1 1
       ttable.2.4 1
       ttable.3.5 1
       ttable.4.2 1
       ttable.5.3 1
       ttable.6.6 1 
       ttable.7.7 1 
}

Works out of the box with PulseAudio.

Typical 5.1 setup that actually works for desktop and video:

pcm.hdmi_direct {
        type route
        slave {
                pcm "hdmi"
        }
        ttable.0.0 1
        ttable.1.1 1
        ttable.2.4 1
        ttable.3.5 1
        ttable.4.2 1
        ttable.5.3 1
}

pcm.hdmi_shared {
        type route
        slave {
                pcm "hdmi_dmixer"
        }
        ttable.0.0 1
        ttable.1.1 1
        ttable.2.4 1
        ttable.3.5 1
        ttable.4.2 1
        ttable.5.3 1
}

pcm.hdmi_dmixer {
        type dmix
        ipc_key 1024
        ipc_key_add_uid false
        ipc_perm 0660
        slave {
                pcm "hw:0,3"
        }
}

pcm.!default {
        type plug
        slave.pcm "hdmi_shared"
}

Works out of the box with PulseAudio. Notice the name of your HDMI
device: "hw:0,3". You can have 4 of them, only one will work. PulseAudio
exposes friendly names for your working outputs only. Others are just not
displayed.

Another common dmix setup:

pcm.!default {
	type plug
	slave.pcm "dmixer"
}

pcm.dmixer  {
 	type dmix
 	ipc_key 1024
 	slave {
		pcm "hw:1,0"
		period_time 0
		period_size 1024
		buffer_size 4096
		rate 44100
	}
	bindings {
		0 0
		1 1
	}
}

ctl.dmixer {
	type hw
	card 0
}

How user-friendly!

With PulseAudio, all that works out of the box. You can switch the
output per application during playback. I want to send music to my other
box where my speakers are plugged, I can do this right from pavucontrol
without interrupting playback.
-- 
Write and test a big program in small pieces.
            - The Elements of Programming Style (Kernighan & Plauger)

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