[opus] Q: Bandwidth vs. bitrate

[Sampo Syreeni]

On 2019-10-30, Ulrich Windl wrote:

> I have some MP3 audio material which is basically speech with some 
> background noises, essentially > 120Hz and < 5kHz. I had the idea to 
> reduce the file size by recoding the material to Opus at 56kbps. 
> Unfortunately the result is a file sampled at 48kHz much larger than 
> the original.

At the risk of sounding blunt...just don't do it? In general perceptual 
compression like MP3, Vorbis or AAC are better reserved for final 
delivery, and are to be avoided in any repeated application. If you once 
chose to compress that way, you really shouldn't reapply the process, 
but rather start with a lossless original/master. Otherwise it's well 
known you could end up with a recording which is 1) higher rate, and at 
the same time 2) of lower quality.
-- 
Sampo Syreeni, aka decoy - decoy at iki.fi, http://decoy.iki.fi/front
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