[ecasound] using rme96 with alsa; four tests

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Subject: [ecasound] using rme96 with alsa; four tests
From: Janroel Koppen (J.Koppen_AT_its.tudelft.nl)
Date: Wed Apr 10 2002 - 11:37:31 EEST

Hi there,

As you might know, having read my previous postings, I'm using an RME
digi96/8 card. Since I still have trouble using the ADAT mode - it gives
an anoying click train - I setup four very simple tests. Can anybody
help me explain the outcome?

First of all I have to give (as root):
> modprobe snd-card-rme96

Then, I try four possible ways of playing out a wave file:

> aplay -D hw:0,0 stereo.wav works (s/pdif)
> aplay -D hw:0,1 stereo.wav error (see below)
> aplay -D plughw:0,0 stereo.wav works (s/pdif)
> aplay -D plughw:0,1 stereo.wav works (ADAT) *NOISY*

0,0 means using the s/pdif channel
0,1 means using the ADAT channel
hw means using the hardware layer
plughw means using the software layer
(I understand that in s/pdif mode coaxial and optical connectors carry
the same signal, so I use optical only, since I can switch my DA
convertor between s/pdif and ADAT reception)

The resulting messages:
Playing WAVE 'stereo.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,
Stereo

Playing WAVE 'stereo.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,
Stereo
play: set_params:724: Channels count non available

Playing WAVE 'stereo.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,
Stereo

Playing WAVE 'stereo.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,
Stereo

So this leads me to the conclusion that the plughw layer converts the
audio to 'fit' 8 channels and does a nasty job. Results are similar with
48000 Hz audio. I still have to repeat the second test with an 8-channel
wave file...

Let's redo the test with ecasound.

ecasound -o alsa,hw:0,0 -i stereo.wav works (s/pdif)
ecasound -o alsa,hw:0,1 -i stereo.wav works (s/pdif)!
ecasound -o alsa,plughw:0,0 -i stereo.wav works (s/pdif)
ecasound -o alsa,plughw:0,1 -i stereo.wav works (s/pdif)!

the resulting message (four times identical):

- [ Chainsetup/Enabling audio inputs ] --------------------
(eca-audio-objects) Audio object "stereo.wav", mode "read".
(audio-io) Format: s16_le, channels 2, srate 44100, interleaved.
- [ Chainsetup/Enabling audio outputs ] -------------------
(eca-audio-objects) Audio object "alsa", mode "write".
(audio-io) Format: s16_le, channels 2, srate 44100, interleaved.
- [ Engine/Init - mixmode "simple" ] ----------------------
- [ Engine/Exiting ] --------------------------------------

Apparently ecosound doesn't care much about the device number (would
this be a bug?). (I know chain setup with ecasound is very flexible, but
if it doesn't recognize the ADAT device in the first place, what's the
use?)

Greetz, Janroel 

-- 
________________________________________________________________
|
| Janroel Koppen, (+31)(0)15-27.86224
| Information & Communication Theory Group,
| Delft University of Technology, The Netherlands
| J.Koppen_AT_its.tudelft.nl, www-ict.its.tudelft.nl/~janroel
|_______________________________________________________________
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