[alsa-devel] Patchmix-style application for EMU cards

Camilo Polymeris cpolymeris at gmx.net
Mon Apr 21 06:42:39 CEST 2008


> That is more or less what I had figured out, but it how are playback_1 to
> > _16 channels routed to DSP0-15? It seems that it depends on the setting
> of
> > Front, Surround, LFE, etc. mixer controls. If they are turned up, I
> don't
> > understand what happens, sound to playback channels appears on various
> > buses, at different levels.
> Really? Well, I didn't much experiment with surround mode. In source code,
> I
> can see that there are up to playback 8 channels at hw:0,0 with can be
> controlled by faders in alsamixer. I tried surround40 and surroun51 on my
> emu1616m and it worked as expected. The channles were mapped to first
> couple
> of DSP ports in a correct order. In fact this should work the same as
> audigy
> does, except the result is passed to DSP ports instead of physical
> outputs.

On my card, playback channels 1 & 2 (hw:0,3) appear on all DSP busses
associated with surround.
Say you turn up the "Side" fader in alsamixer, channels 1 & 2 will appear at
the relevant DSPs (6-7, I think)
Whatever, for now I am just keeping all surround controls down (that is,
Front, Surround, Center, Side & LFE).

> Anyway, I think if there is another layer of routing done in audigy DSP,
> it
> shouldn't be used in EMU specific application. Or at least not for now.
> The
> most important thing is to provide all the switches and FPGA routing
> scheme
> for each EMU model. Or, to be precise, three routing schemes for each EMU
> model, because for "double speed" (e.g. 96kHz) and "quadro speed" (e.g.
> 192kHz) modes of operation the numebr of both physical and virtual
> channels
> changes.

I think the switches and enums for the card models are rather trivial, one
can handle it with a customized version
of qamix (done with a simple XML file), for example. A separate application
would not be necessary for only that.

> > If I turn the Front/Surround/LFE/etc. faders down, I can mix playback
> > channels to DSP using the "Multichannel PCM Send/Routing/Volume" faders,
> in
> > a more or less intuitive way, besides that routing values do not map
> > directly to DSP buses (i.e. 14-15 map to DSP0-1, but 2-3 map to DSP2-3).

Handling of this controls motivated me to write the application in the first
No sound at all will appear if I don't set the appropiate controls for each
playback channel: Multichannel PCM Volume (full), Multichannel PCM Send (an
index of 8 controls, the first 4 select the target DSP) & Multichannel PCM
Send Volume (again faders 0-3 of 8)
By the way, only DSP0-7 work in this way. I have no idea how to make DSP8-31

On which card you did tested it? The driver was primary written for the
> 1820M/1212M V1, so some things may not work well on other models and need
> to
> be fixed.

I have a 1212m, don't know which version, but I think it's V1-- it does have
I am using driver version 1.0.16.


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