[Speex-dev] Re: aec

[Jason Harper]

When I ran test 4 as originally described there is
substantial echo cancellation (but not as good as when
the files are perfectly aligned).  When I invert the
inputs, there is no noticeable cancellation.
I'm using testecho with the preprocess line commented
out.  Preprocess seems to work very well at cleaning
up the residual echo when mdf does its job, so I'm
just focusing on testing mdf.

-Jason

--- Jean-Marc Valin <Jean-Marc.Valin at USherbrooke.ca>
wrote:

> First try your test #4 (same signal and offset) and
> swap the inputs.
> 
> 	Jean-Marc
> 
> Le mercredi 09 novembre 2005 à 22:44 -0800, Jason
> Harper a écrit :
> > I'm pretty much sure of it.  When I test inverting
> the
> > inputs, my output is pretty much the same as my
> > speaker signal.  Whereas the way that I normally
> test
> > the output is my mic signal with very little
> > attenuation.
> > If you are interested I can send my test files;
> they
> > are about 94KB each.
> > 
> > -Jason
> > 
> > --- Jean-Marc Valin
> <jean-marc.valin at usherbrooke.ca>
> > wrote:
> > 
> > > Are you sure you're not just inverting the two
> > > inputs?
> > > 
> > > 	Jean-Marc
> > > 
> > > On Wed, 2005-11-09 at 22:16 -0800, Jason Harper
> > > wrote:
> > > > I ran some further tests on mdf and here are
> the
> > > > results:
> > > > 1. reduced tail length to 100ms, aligned mic
> and
> > > > speaker signals to within 10ms - almost no
> echo
> > > > attenuation
> > > > 2. aligned mic and speaker signals to within 5
> > > samples
> > > > - still almost no echo attenuation
> > > > 3. ran testecho using the same file for mic
> and
> > > > speaker - very good echo cancellation (of
> course
> > > this
> > > > is expected, but I needed to do a sanity
> check)
> > > > 4. ran the same file for mic and speaker, but
> had
> > > the
> > > > mic signal delayed by 10ms - OK echo
> cancellation,
> > > but
> > > > noticeably degraded over previous test
> > > > 5. same file for mic and speaker, but mic
> signal
> > > > delayed by 40ms - noticeable echo attenuation,
> but
> > > > still a large echo.
> > > > 
> > > > So far my testing is only showing good echo
> > > > cancellation when the exact same file is being
> > > used
> > > > and is pretty closely aligned.
> > > > 
> > > > -Jason
> > > > 
> > > > --- Jean-Marc Valin
> > > <Jean-Marc.Valin at USherbrooke.ca>
> > > > wrote:
> > > > 
> > > > > This kind of behaviour is odd. One of the
> reason
> > > > > could be the fact that
> > > > > you're using a really long impulse response.
> Try
> > > > > syncing your signals
> > > > > and making the tail length more in the order
> of
> > > 100
> > > > > ms to 300 ms.
> > > > > 
> > > > > 	Jean-Marc
> > > > > 
> > > > > Le dimanche 06 novembre 2005 à 21:25 -0800,
> > > Jason
> > > > > Harper a écrit :
> > > > > > Thanks for alerting me to the new changes.
>  I
> > > just
> > > > > > tried the latest code from SVN, but
> > > unfortunately
> > > > > I
> > > > > > still have just about the same results. 
> The
> > > > > estimated
> > > > > > echo that gets subtracted from the actual
> echo
> > > is
> > > > > such
> > > > > > a small signal that it doesn't really
> result
> > > in
> > > > > any
> > > > > > noticeable echo attenuation.
> > > > > > I currently have my filter size set to 2
> > > seconds
> > > > > even
> > > > > > though the echo in my microphone file is
> only
> > > > > about
> > > > > > 180ms delayed from the signal in my
> speaker
> > > file. 
> > > > > I
> > > > > > also double checked that the endianess of
> my
> > > is
> > > > > > correct, and that I am providing the files
> to
> > > > > testecho
> > > > > > in the correct order.
> > > > > > Do you think that there could be some
> > > > > characteristics
> > > > > > to my echo that make it not work with the
> mdf
> > > > > > algorithm?  How much echo attenuation
> should I
> > > > > expect
> > > > > > from the mdf algorithm before the
> preprocess? 
> > > Are
> > > > > > there any test speaker and mic files that
> I
> > > could
> > > > > run
> > > > > > against testecho to see how it handles
> other
> > > > > acoustic
> > > > > > echos?
> > > > > > 
> > > > > > -Jason
> > > > > > 
> > > > > > --- Jean-Marc Valin
> > > > > <Jean-Marc.Valin at USherbrooke.ca>
> > > > > > wrote:
> > > > > > 
> > > > > > > I've recently made changes to the AEC.
> > > Please
> > > > > try
> > > > > > > the code in SVN and
> > > > > > > see if it works better.
> > > > > > > 
> > > > > > > 	Jean-Marc
> > > > > > > 
> > > > > > > Le jeudi 03 novembre 2005 à 22:36 -0800,
> > > Jason
> > > > > > > Harper a écrit :
> > > > > > > > I've tried some further debugging to
> see
> > > what
> > > > > mdf
> > > > > > > is
> > > > > > > > actually doing.  Instead of sending:
> > > > > > > > tmp_out = (float)ref[i] -
> > > > > st->y[i+st->frame_size]
> > > > > > > > to the output, I just sent
> > > > > > > > st->y[i+st->frame_size]
> > > > > > > > to see what was being subtracted from
> the
> > > > > > > microphone
> > > > > > > > input.  When I open this in Audacity,
> I
> > > see a
> > > > > very
> > > > > > > > small signal at about -40dBm.  The
> actual
> > > echo
> > > > > in
> > > > > > > my
> > > > > > > > sample has a power closer to -20dBm. 
> So,
> > > when
> > > > > the
> > > > > > > > -40dBm estimated echo is removed from
> the
> > > > > -20dBm
> > > > > > > > actual echo there is almost no
> perceived
> > > > > > > difference in
> > > > > > > > the echo power.
> > > > > > > > I'm sure that there are others on the
> list
> > > > > that
> > > > > > > have
> > > > > > > > had good success with the echo
> > > cancellation
> > > > > > > module. 
> > > > > > > > Could anyone point me to reference
> test
> 
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