[opus] a problem with bandwidth configuration

Timothy B. Terriberry tterribe at xiph.org
Mon Aug 3 15:25:46 PDT 2015

Michal Weiss wrote:
> It seems that the encoder's bandwidth is always the same as the input
> sample rate.
> Dows't it suppose to make a rate convertion?

Audio bandwidth is not the same thing as sample rate. Even if you fed 
the encoder 48 kHz data, if there was no signal energy above 8 kHz (or 
at sufficiently low bitrates) it could choose to use a WB config, and 
could change this decision on a packet by packet basis.

The decoder can decode any configuration at any sample rate. If you pass 
the encoded output of ./opus_demo -e audio 16000 ... to ./opus_demo -d 
48000 ... you will get 48 kHz output.

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