Re: [ecasound] 1.6.x development info

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Subject: Re: [ecasound] 1.6.x development info
From: Kai Vehmanen (
Date: Wed Oct 27 1999 - 02:37:25 EEST

On Sun, 24 Oct 1999 wrote:

>> surround reverbs and other multichannel effects to chains as usual.
>> If you connect these effects to mono channels, they won't work of
>> course, but this shouldn't be a problem. If you connect a mono-effect
> What actually would happen? Strange sounds? Segfault? Mysterious
> corruption of unmounted drives?

No, no. It depends on how effects are implemented. In 1.6.x, effects
access sample data through iterator classes. Currently I've implemented
four iterator types:

1) normal
 --- all samples in the buffer, not in any specific order,
 --- example: amplify
2) channels
 --- all samples, one channel at a time, examples: filters, delays
 --- and other effects that require info about past sample data
3) channel
 --- like (2), but only one channel, example: channel amplify,
 --- left-right panning
4) interleaved
 --- all samples, channels are interleaved, examples:
 --- surround effects, mixing

So effect don't know much about the actual representation of sample
data, or where the samples are coming from. If effect asks: "I want to
process the 4th channel", but there's only one channel, it won't get
any samples. On the other hand, amplify effect will happily process
a reversed 128-channel audio buffer using the "normal" iterator. ;)

Kai Vehmanen <> -------- CS, University of Turku, Finland
 . - linux audio processing
 . - ambient-idm-rock-... mp3/ra/wav
 . - music&movies (in Finnish)

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