[Speex-dev] Problems with Speex Resamplers

[John Ridges]

Colin,

If you're using stereo audio with the resampler, there is a bug that can 
occur under certain situations (and maybe that's what's been happening 
to you). Check out:

http://lists.xiph.org/pipermail/speex-dev/2009-August/007406.html


With that patch, I've used the resampler extensively in many situations 
without any problems.

John Ridges


On 12/3/2010 1:00 PM, speex-dev-request at xiph.org wrote:
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> Today's Topics:
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>     1. Problems with Speex Resamplers (Colin Guthrie)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 03 Dec 2010 11:12:06 +0000
> From: Colin Guthrie<gmane at colin.guthr.ie>
> Subject: [Speex-dev] Problems with Speex Resamplers
> To: speex-dev at xiph.org
> Cc: pulseaudio-discuss at mail.0pointer.de
> Message-ID:<idaja6$sjj$1 at dough.gmane.org>
> Content-Type: text/plain; charset=UTF-8
>
> Hi Everyone,
>
> Just wanted to let people know that we've uncovered some problems with
> the speex resamplers in PulseAudio
>
> The problem generally manifests itself when having the following setup.
>
> * Server Sample Rate: 44100
> * Resampler: speex-* (both fixed and float)
> * Playing a 48000 stream
>
> The problem only really manifests itself in the first 500ms or so of the
> stream and then generally clears itself out so it's not always obvious
> when listening to e.g. music, but for event sounds etc. it's quite
> apparent (KDE event sounds are technically played via
> Phonon->GStreamer->PA, and as GST lets PA do the resampling, it will
> exhibit the problem - FWIW, I believe this pipeline for event sounds is
> insane and I am actively trying to change that[1], but it's beside the
> point).
>
>
> I opened this bug https://bugzilla.gnome.org/show_bug.cgi?id=636294 to
> report a GST problem but it very much is a problem in either Speex or
> our use of it. The above contains some test cases to recreate the issue
> easily via gst but it would be possible to cause this via other systems too.
>
>
> I have tried:
>   1. Calling speex_resampler_skip_zeros() on init and reset: no change.
>   2. Applying a fix found here.
> http://thread.gmane.org/gmane.comp.audio.compression.speex.devel/6833
> (no replies on the speex-dev list to that one... not sure if it's needed
> etc.
>
>
> Nothing above seemed to help.
>
> Any advice or debugging tips welcome. The trivial and sinc resamplers
> seem to work fine FWIW.
>
>
> Cheers
>
> Col
>
>
> References
> 1. http://thread.gmane.org/gmane.comp.kde.users.multimedia/5979
>
>