[opus] Help with OpusEnc

Ralph Giles
Wed, 12 Feb 2014 18:11:41 -0000

On 2014-02-11 8:27 PM, Ben wrote:

> New to list and Opus Codec.

Welcome1

> One of the things I've noticed while encoding is that Opus reports a
float with an 'x' along with "realtime".

This is intended to measure the cpu performance of the encoder. The
float is the number of seconds of audio data processed divided by the
number of real-time seconds since encoding began.

If openenc displays '1x realtime' then the encoder is only just keeping
up with the input data from arecord. If it displays '524x realtime' then
it would need only .5% cpu to keep up with a live stream.

> Where can I look up where this calculation is derived?

The value is computed here:
https://git.xiph.org/?p=opus-tools.git;a=blob;f=src/opusenc.c;h=366893b7af325a67be90b33f991426a2c5665ef9;hb=HEAD#l1030

> The new recording is shorter than the original by significant amounts.

Shorter as in data is missing, or that the playback length doesn't
exactly match the walltime while you were recording? This could be a
couple of different things.

 -r