[Speex-dev] How to use aec correctly?

ac2491 at columbia.edu ac2491 at columbia.edu
Tue Aug 8 18:49:32 PDT 2006


For me AEC fails terribly on Dell Axim PDA. It has a high nice 625
Mhz processor.

AEC for me works on desktop. I maintain a queue of packets played on
speaker and a queue of packets captured through mic. These queue are
requirde since I am using Windows waveform APIs which behave in an
unexpected manner, as they are callback oriented. But with the
queues in place you can get the syn down to a level where a tail of
12*160(160 is the number of samples) , actually lesser, so it works
on a desktop.

Point to note is that I need to use speex_preprocess call otherwise
there is a trail of echo remaining which when high gets amplified
on each succesive pass.

On a PDA with only the call to speex_echo_cancel, the whole thing
becomes so slow, that wit just does not work.

I am using latest speex from SVN and fixed_point compilation on a
Dell Axim PDA (which looks like having some nice processing power
as compared to other PDAs)

Any advice on why speex_echo_cancel call takes so long, messes up
the normal packets also without any echo (wear headphones).


Quoting keith <qzyxm at 126.com>:

> Hi,all
>   I have tested AEC on files, it works well.I have some files,one
> is echo
> file, others are echo-added files(an origin file adding echo at
> different
> delay,such as 20ms,40ms...120ms,140ms).AEC do wonderfully on
> those files
> except echo added at 140ms-delay.
>   But ,when i use AEC in my voip project, it does feebly. Who can
> give me
> some hints why caused this.How long can  sound be picked up by
> mic after it
> plays out.This is the main problem to align echo.Give me a hint.
> Best regards
> keith
> _______________________________________________
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> Speex-dev at xiph.org
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