Re: [ecasound] channel manipulation

From: Patrick Shirkey <pshirkey@email-addr-hidden>
Date: Sat Sep 29 2012 - 00:56:34 EEST

On Sat, September 29, 2012 7:30 am, S. Massy wrote:
> On Sat, Sep 29, 2012 at 06:31:36AM +1000, Patrick Shirkey wrote:
>> On Sat, September 29, 2012 6:19 am, S. Massy wrote:
>> > It's a long shot, but are you aware that loop devices introduce a
>> delay
>> > of one buffersize (so about 21.3 MS for -b:1024)? If you have anything
>> > like a periodic signal, this could conceivably cause some
>> cancellation.
>> >
>> The test track is 5 seconds of one person talking.
>> Do you mean cancellation in the playback or cancellation in the chain
>> signal?
> You should still see some frequencies though for this type of signal, so
> that can't be it.
> Just to be clear, are you saying the setup works when no loop devices
> are used but desn't (silence on those channels) when loop devices are
> used? If so, then it certainly looks like a bug (undocumented feature?)
> with loop devices and channel manipulation.

There are several issues that this process has put in the spotlight which
could be caused by bugs, user error or documentation.

1: If I use a loop device the signal is silent on the output track for
channels 5,6

2: If I don't use a loop device I get an error for a "multi" chain (a:5,6)
that I do not get on a "mono" chain (a:1)

-a:5 -chmute:1 -ea:-100 \
-a:6 -chmute:2 \
-a:5,6 -chmix:5 \

    ecasound: ERROR: [ECA-SESSION] : "Invalid argument, unable to parse:

3: If I don't use a loop device and I can't chmix a "multi" chain how do I
mix two channels : inverse right + left : without resorting to writing
mono files in a multi pass process?

4: Why does a loop think it has a live input if the chain input is a file?

Of course I could do things the long way which would probably save me some
time but I would rather invest some time into these issues while I am
looking at them so that everyone might benefit from the resolution. At
least if we know they are problems we can start thinking about how to fix
them. If it is all user error then at least I will learn how to use
ecasound properly :-)

Patrick Shirkey
Boost Hardware Ltd
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Received on Sat Sep 29 04:15:01 2012

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