[Speex-dev] Output sampling rate slightly increased. Will speexcomplain?

John Miles jmiles at pop.net
Tue Jun 5 13:37:28 PDT 2007


It is a good idea not to use sample rates other than 44100 or 48000 Hz for
your final audio I/O.  The chipset people just do not give a crap about
rates other than that.  They don't see a problem with giving you 11100 Hz
when you ask for 11025, for instance, even though that's a huge problem for
VoIP.

Ultimately you need to be prepared to resample to one of the de-facto
'standard' rates if timing is important.

-- john
  -----Original Message-----
  From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org]On
Behalf Of marzullo maio
  Sent: Tuesday, June 05, 2007 10:06 AM
  To: speex-dev at xiph.org
  Subject: [Speex-dev] Output sampling rate slightly increased. Will
speexcomplain?


  I noticed my latency is gradually increasing in my audio loopback test
application. I just hear what i say, encoding and decoding on the fly.
  I suppose 8000 Hz for the output device is not 8000 Hz for the input one,
they differs since they could refer to different time generators (i
suppose...).

  To solve the problem i rised the output sampling rate from 8000 to 8200
Hz, and now i'm not accumulating latency anymore. The quality remains
practically the same. The input sampling rate is still 8000 Hz. That's it, i
just need a faster consumer (audio output) than producer (audio input).

  Actually i'm telling the encoder/decoder i'm sampling at 8000 Hz either
for input and output. Should i tell speex i'm using this trick?

  Please give me some suggestions, should the speex be involved in some way?
  I'm not experiencing any noticeable difference through except the latency
which is now constant.

  Could be another solution to the latency rising issue?

  Thanks.

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