[opus] Opus frame size

[Timothy B. Terriberry]

Manpreet Singh wrote:
> this overhead. Is there any significant downside in using a higher frame
> size for VoIP applications?

The only real downside is latency. If you're targeting a latency of 150 
ms and your network stack, jitter buffer, etc., add 2-3 packets worth of 
latency, then 60 ms frames put you in danger of blowing your latency 
budget even if your network is infinitely fast.

> Secondly, the sweet spot is mentioned as 16-20kbps for wideband speech
> "for a 20ms frame". Assuming this is just the codec bitrate (without any
> headers), does the frame size really influence the Opus bitrate?

Frame sizes larger than 20 ms will have similar quality at similar 
bitrates. If you want smaller frames, you will have to increase the 
bitrate to maintain the same quality.