Re: [ecasound] channel manipulation

From: Patrick Shirkey <pshirkey@email-addr-hidden>
Date: Fri Sep 28 2012 - 22:41:14 EEST

On Sat, September 29, 2012 2:05 am, S. Massy wrote:
> On Fri, Sep 28, 2012 at 11:23:09AM +1000, Patrick Shirkey wrote:
>> ecasound -t 5 -f:s16_be,6,48000 \
>> -a:1,2,3,4,5,6 -i TEST_1-2.aif \
>> -a:1 -chmute:2 \
>> -a:2 -chmute:1 \
>> -a:3 -chmix:3 \
>> -a:4 -chmix:4 \
>> -a:5 -chmute:1 \
>> -a:6 -chmute:2 \
>> -a:5,6 -chmix:5 -chcopy:5,6 \
>> -a:all -o test-out.wav
>> +++
> I've only skimmed this thread as it unfolded, but I must say I'm a bit
> puzzled as to what exactly you are trying to achieve: could you explain?
> Why do you keep mixing the signal with itself?

I have stripped each chain of it's respective filters to make sure that
the actual chain is correct and avoid any further confusion.

> All this channel manipulation can obfuscate things somewhat; perhaps a
> simple way to debug could be to employ a two step method where you send
> each channel to a single wave file and then rejoin them in a 6-channel
> file again. Once you get the expected result, you could just modify your
> setup to do it in one go.

I've already done that. My objective is a complete chain setup and I would
like to know why the code I have is not working. As far as I can tell it
should result in valid output on channels 5,6. It doesn't make any sense
that the output on those channels is silent.

It should be possible to get the signal into 6 different channels as long
as the chain setup is valid right?

However if it is simply in the too hard basket or not interested in
aswering this question right now or don't have time to look into it then I
will move on to a new method and abandon the single pass objective for

It seems like I have found a limitation in ecasound and my question is am
I doing something wrong with this chain or is this a new bug that has
been found?

Nothing wrong with finding bugs. If it is a bug then at least we know it
exists and if it is not then it must be a logic error on my part.

As an aside this is one of the benefits of doing professional work with
the Linux Audio tools. Things like this tend to be found and that means we
can look at fixing them. If it is a real bug then we can fix the code, if
not then we can fix the docs. It's no surprise that this particular chain
setup is not documented. I'm sure once we figure it out we will be able to
add it to the examples page for everyone to benefit from...

Patrick Shirkey
Boost Hardware Ltd
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Received on Sat Sep 29 00:15:01 2012

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