[opus] advantage of OPUS_SET_FORCE_CHANNELS(1)?

Timothy B. Terriberry tterribe at xiph.org
Mon Oct 23 02:19:33 UTC 2017

Phil Karn wrote:
> This works well, but then I noticed the SET_FORCE_CHANNELS option. Is
> there any advantage to my detecting identical left and right channels
> and setting this to force mono? Or does the Opus encoder already do this
> internally in the AUTO mode?

No, the automatic setting should be fine. The purpose of this setting is 
for the case where you know the receiver will only use a mono decoding 
path. This is common in some VoIP applications. It lets you avoid coding 
a stereo signal even when you have stereo input, e.g., because you know 
through out-of-band means that the receiver will discard the stereo 
image anyway.

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