Re: [ecasound] Fun with the PAN -epp command

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Subject: Re: [ecasound] Fun with the PAN -epp command
From: Kai Vehmanen (
Date: Tue Feb 29 2000 - 16:51:22 EET

On Tue, 29 Feb 2000, Neil E. Klepeis wrote:

> 2. -a:0 -f:16,1,44100 -i TESTstereo.mp3 -ea:100 -epp:100 -a:0 -o
> /dev/dsp1
> #2 results in nothing (i.e., no sound).

Yes, as it should. Let's see what happens.

1. Chain '0' is created - channel count still unknown.
2. You set the default audio format to 16,1,44100.
3. Mp3-file is opened and it's treated as a 16,1,44100
   (mono) file. Btw; if you could hear it, you'd get
   a half-speed version of the mp3-file. After creation,
   input is connected to the active chain '0'.
   Chain channel count is now adjusted to the
   attached input (==> 1 channel).
4. A amplify effect is added. This doesn't change channel
5. You add the pan-effect. -epp is a stereo-effect, so
   chain's channel-count is increased to 2 (stereo).
6. /dev/dsp1 is opened as a mono device and attached
   to chain '0'

Now when you start processing...:

channel input-mp3 -> chain-0 -> output-dsp1

0-left read process write
1-right - process -


So when you pan your signal fully right, you won't hear anything on the left channel (which happens to be the only one written to /dev/dsp1).

> 2. -a:0 -f:16,1,44100 -i TESTstereo.mp3 -ea:100 -epp:100 -a:0 -o /dev/dsp1

ecasound -a:0 -f:16,2,44100 -i TESTstereo.mp3 -epp:100 -o /dev/dsp1

> 3. -a:0 -f:16,1,44100 -i TESTstereo.mp3 -ea:100 -epp:0 -a:0 -o /dev/dsp1

ecasound -a:0 -f:16,2,44100 -i TESTstereo.mp3 -epp:100 -o /dev/dsp1

> 4. -a:0 -f:16,2,44100 -i TESTmono.mp3 -ea:100 -a:0 -o /dev/dsp1

ecasound -a:0 -f:16,1,44100 -i TESTmono.mp3 -o /dev/dsp1

> 5. -a:0 -f:16,1,44100 -i TESTmono.mp3 -ea:100 -epp:0 -a:0 -o /dev/dsp1

ecasound -a:0 -f:16,1,44100 -i TESTmono.mp3 -erc:1,2 -epp:0 -f:16,2,44100 -o /dev/dsp1

> 6. -a:0 -f:16,1,44100 -i TESTmono.mp3 -ea:100 -epp:100 -a:0 -o /dev/dsp1

ecasound -a:0 -f:16,1,44100 -i TESTmono.mp3 -erc:1,2 -epp:100 -f:16,2,44100 -o /dev/dsp1

> I'm still getting used to this whole thing, so please bear with me if > I'm missing something stupid.

No, no, these routing-related issues are still not that well documented. This is a good opportunity for me to explain my ideas.

-- Kai Vehmanen <> -------- CS, University of Turku, Finland . - linux multitrack audio processing . - ambient-idm-rock-... mp3/ra/wav

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