Speex dev - Apr 2011 - lpcSize

I would like to make lpcSize a multiple of 4.  In the current library for narrow
band mode lpcSize is currently set to 10.  I would like to increase this 12 for
optimization reasons.  Is it a simple matter of just changing lpcSize in the
structures in mode.c or are there other implications to doing this?

I did try and change the value but I seem to be getting some runtime errors
indicating a stack corruption.  This seems to indicate that I am not allowed to
just change the value in the struct.  Is there a way for me to alter the lpcSize
without having to rewrite sections of code?

Thanks,

Vasant Shridhar
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On 11-04-11 11:05 AM, Shridhar, Vasant wrote:
> I would like to make lpcSize a multiple of 4. In the current library for
> narrow band mode lpcSize is currently set to 10. I would like to
> increase this 12 for optimization reasons. Is it a simple matter of just
> changing lpcSize in the structures in mode.c or are there other
> implications to doing this?
Nothing major except you'd need to rewrite the LSP quantizer, retrain 
half the codebooks, change the bit-allocation and break compatibility 
with the format.

Cheers,

	Jean-Marc

Okay,

Not exactly the answer I was looking for.  This sounds like a big change.  I
don't mind re-writing the LSP quantizer but re-training code books and
breaking compatibility is not what I want to do.  I am working on an
optimization for an ARM cortex-A8.  It is desirable to process things in 4
element blocks.  Is there a simpler approach you could recommend?

Vasant Shridhar
________________________________________
From: Jean-Marc Valin [jmvalin at jmvalin.ca]
Sent: Monday, April 11, 2011 5:29 PM
To: Shridhar, Vasant
Cc: speex-dev at xiph.org
Subject: Re: [Speex-dev] lpcSize

On 11-04-11 11:05 AM, Shridhar, Vasant wrote:
> I would like to make lpcSize a multiple of 4. In the current library for
> narrow band mode lpcSize is currently set to 10. I would like to
> increase this 12 for optimization reasons. Is it a simple matter of just
> changing lpcSize in the structures in mode.c or are there other
> implications to doing this?
Nothing major except you'd need to rewrite the LSP quantizer, retrain
half the codebooks, change the bit-allocation and break compatibility
with the format.

Cheers,

        Jean-Marc