[Speex-dev] Problems with Speex Resamplers

Sherief N. Farouk sherief at mganin.com
Mon Dec 6 06:52:41 PST 2010

How much latency are we talking about? It seems that this issue cannot be
easily pinpointed, but if it turns out to be related to the Speex Resampler
let me know and I will put it on my task list.

- Sherief

-----Original Message-----
From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org] On
Behalf Of Colin Guthrie
Sent: Monday, December 06, 2010 9:47 AM
To: speex-dev at xiph.org
Subject: Re: [Speex-dev] Problems with Speex Resamplers

'Twas brillig, and Sherief N. Farouk at 06/12/10 14:29 did gyre and gimble:
> If you can produce a simple minimal repro that exhibits this issue on some
> procedural signal (sine wave, etc) I'd love to look into it some more -
> maintaining a hardened version of the Speex Resampler and would be very
> concerned if this bug made it into production.

Well at present, I'm not sure it is a bug at all.

I suspect that it is in some capacity related to PulseAudio's rewinding
that causes this. e.g. a new sounds starts that triggers a rewind, and
the resampler is reset and some other rewind happens and the latency of
the resampler during this reset phase is somehow longer than we need it
to be or something along those lines. After the rewind is dealt with,
then the latency of the resampler is not a problem any more... (and not
resetting and doing other such things also prevents overhead).

I'm not sure about the above hand-wavey, vague explanation but I suspect
it's something in that general area that's causing the problems rather
than a bug in speex per se.



Colin Guthrie

Day Job:
  Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
  Mageia Contributor [http://www.mageia.org/]
  PulseAudio Hacker [http://www.pulseaudio.org/]
  Trac Hacker [http://trac.edgewall.org/]

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