Hi,
(I removed alsa-users from Cc)
At Fri, 20 Sep 2002 10:56:01 +0200,
Gerard Janssen wrote:
>
> I tried to find the spdif output port addresses by changing the register
> addresses of EXTOUT_TOSLINK_L/R in emu10k1.h to all 16 possible output
> address pairs between (00 - 1f). To do this, I removed the extout_mask
> check in emufx.c in the piece of code given below. I found the addresses of
> the four spdif output ports of the SBLive! card (I did/could not check this
> for the Audigity) and they are as follows: spdifo#0 = (0x02,0x03), which is
> the standard output, spdifo#1 = (0x04,0x05), spdifo#2 = (0x06,0x07) and
> spdifo#3 = (0x08,0x09).
>
> So in principle it seems to be possible to create 8 digital output channels
> on the SBLive!, however at the cost of some of its standard
> functionalities, namely the outputs of the center_lfe, headphone and rear
> channels to the LiveDrive (I think?).
it's interesting.
are signals sent to all spdif outs without changing any other reigisters?
>
> Now, I would like to implement three additional spdif outputs in the same
> way as the standard output, so without volume or tone control. I think,
> this is an interesting extension of the functionality of the SBLive, since
> by creating 8 independent digital outputs we get a functionality on a cheap
> soundcard which is now only available at expensive (professional) soundcards.
> The problem is that I am not a programmer, however, I would like to give it
> a try where any help from the ALSA community is very much appreciated. I
> have the following questions:
>
> 1. Is the code related to the standard spdif output in emufx.c, limited to
> the following code lines or is there other code involved?
> if (emu->fx8010.extout_mask &
> ((1<<EXTOUT_TOSLINK_L)|(1<<EXTOUT_TOSLINK_R))) {
> /* IEC958 Optical Raw Playback Switch */
>
> for (z = 0; z < 2; z++) {
> SWITCH(icode, &ptr, tmp + 0, 8 + z, gpr + z);
> SWITCH_NEG(icode, &ptr, tmp + 1, gpr + z);
> SWITCH(icode, &ptr, tmp + 1, playback +
>SND_EMU10K1_PLAYBACK_CHANNELS +
> z, tmp + 1);
> OP(icode, &ptr, iACC3, EXTOUT(EXTOUT_TOSLINK_L + z), GPR(tmp +
>0),
> GPR(tmp + 1), C_00000000);
> }
> snd_emu10k1_init_stereo_onoff_control(controls + i++, "IEC958 Optical
>Raw
> Playback Switch", gpr, 0);
> gpr += 2;
> }
the code above implements a switch for "raw" playback (e.g. ac3).
at the first step, you can skip this switch and route wet signals like
others.
>
> 2. To what address does "tmp" refer in the OP instruction above?
initialized at the beginning of the function. it's 0x88.
as imagined from its name, it's a temporary GPR.
> 3. Do I need to implement additional "Process FX Buses" (now there are 9
> buses, indicated as GPR(0) - GPR(9), where GPR(8) and GPR(9) have the
> comment S/PDIF left/right)?
we might need more two FX buses for all 4 separate outputs (see below
my comments).
GPR(8) and (9) are used for raw playback, so additionally we need more
if 4 raw playbacks are needed, too.
> 4. I thought that the spdif channel status registers SPCS0-3 (I added an
> SPCS3 on address 0x57 in emu10k1.h) were initialized in emu10k1_main.c.
> However, after playing a wave file using aplay via spdif at 44.1 kHz, the
> sample frequency in SPCS is changed from 48 kHz to 44.1 kHz. Also other
> changes appear in some SPCS values, which I cannot trace back. Where in the
> code is the SPCS value changed?
SPCS is changed in snd_emu10k1_spdif_put() (in emumixer.c).
the value is changed if you open the pcm with arguments like
AES0=xxx.
the necessary changes would be to add controls to change other SPCS
registers via mixer (and more "raw playback" switches if necessary).
basically, the routing can be controlled via a mixer control element.
that is, to which FX bus and how much the signal is sent.
on the current code, you cannot separate spdif #1 and #2, since both
use the same center/lfe source. thus, we can define new FX channels
for them and mix if neceessary.
even with the current code, you can change the routing like the
following:
SPDIF #0
normal spdif playback
% aplay -Dspdif ...
SPDIF #1
(adjust Wave Center Playback Volume
Wave LFE Playback Volume)
% aplay -Dcenter_lfe ...
SPDIF #2
(toggle Headphone Center Playback Switch,1
and Headphone LFE Playback Switch,1
adjust Headphone Playback Volume,1
in addition to the volumes for spdif#2)
% aplay -Dcenter_lfe ...
SPDIF #3
(adjust Wave Surround Playback Volume)
% aplay -Drear ...
Takashi
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