Audio Sample Rate with Jack and GStreamer

Sebastian Dröge sebastian at
Wed Apr 2 11:26:22 PDT 2014

On Mi, 2014-04-02 at 07:49 -0700, Scott Kidder wrote:
> Hi all,
> Where's the best place to specify the audio sample-rate when using Jack and
> GStreamer to encode with the Opus codec?  Should the sample-rate be
> specified in the Jack config, GStreamer pipeline, or both?
> I'd like to have the Opus codec use a sample rate of 24000 instead of the
> default of 48000.  It seems that it would be best to have Jack use a
> sample-rate of 24000, so as to reduce the load on Jack and eliminate the
> need to resample in the GStreamer pipeline.  Is this advisable?
> [...]

Opus always uses a sample rate of 48kHz. If you pass it anything else it
will internally resample to 48kHz before encoding.

But if Opus would support other sample rates it would be best if the
recording from the sound device already would happen with 24kHz and no
software resampling is happening. If that's not possible it doesn't
really matter much where the resampling happens in software, other than
that it shouldn't be done multiple times into different sample rates.

Sebastian Dröge, Centricular Ltd -
Expertise, Straight from the Source
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