[FFmpeg-user] ffmpeg not honoring requested sample rate when outputting opus to .ogg

[Carl Eugen Hoyos]

Hi!

2016-08-29 4:06 GMT+02:00 Adam Langley <ffmpeg.org at irisdesign.co.nz>:
> I am capturing a live audio stream to Opus, and no matter what I
> choose for the audio sample rate, I get 48khz in the output file.

This is how Opus works (and not FFmpeg-related).

[...]

> I should also mention, that VLC also reports the file as being 48Khz -
> and the file size is way too big to be 16khz - so I'm pretty confident
> that it actually contains 48000 samples per second of data....

I may misunderstand you, but this is not how compressed audio
works generally (not only for Opus).

> I decoded the file to WAV, then used opusenc to compress it back
> to 16Khz, and it was way smaller....

You will get a smaller output file with FFmpeg if you select a smaller
bitrate.

Carl Eugen