Subject: Re: [ecasound] trouble panning with -epp
From: Kai Vehmanen (k_AT_eca.cx)
Date: Tue Oct 23 2001 - 01:53:07 EEST
On Mon, 22 Oct 2001, CLOTILDE Guy Daniel wrote:
>> I've got 3 single channel tracks that I want to pan across the left to
>> right sound field. I'm using the following ecs script:
> ----cut-------
> -f:16,1,44100
> -a:1 -epp:0 -ea:500 -i:sax1.wav -ea:500 -erc:1,2 -epp:0
> -a:2 -epp:50 -ea:500 -i:trumpet1.wav -ea:500 -erc:1,2 -epp:50
> -a:3 -epp:100 -ea:500 -i:trombone1.wav -ea:500 -erc:1,2 -epp:100
> -a:all -f:16,2,44100 -o:alsa,default
> ----cut-------
You have the right idea. The minimum setup to do panning of mono-files
would be:
--cut--
-a:1 -i:sax1.wav -erc:1,2 -epp:0
-a:2 -i:trumpet1.wav -erc:1,2 -epp:50
-a:3 -i:trombone1.wav -erc:1,2 -epp:100
-a:all -f:16,2,44100 -o:alsa,default
--cut--
The actual signal chain is something like ('---' = mono channel)
sax1.wav |--'1'---- erc ----| epp |---\
\-----| |---\\
\\
trumpet1.wav |--'2'---- erc ----| epp |------- | alsa,default
\-----| |------- |
//
trombone1.wav |--'3'---- erc ----| epp |---//
\-----| |---/
The critical points are:
- ecasound automatically notices that the three
input files are mono files
- chains contain mono signal until -erc operator,
which transforms the chain into a stereo chain
- now -epp works as excepted
- chains are mixed to the alsa device channel-wise
If you leave out the -erc effect, chains will still be converted to
stereo, but on each chain, only the first channel (left) will contain any
audio from the input files.
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