[opus] Info OPUS encoder

Ralph Giles giles at thaumas.net
Wed May 15 10:23:09 PDT 2013

On 13-05-15 12:47 AM, van Bijleveld Christian (ST-CO/ENG1.3) wrote:

> More specifically, I am interesting in knowing how should I interpret
> the Runtime information ‘6.86e+06x realtime’,

This is a basic performance benchmark. The measured execution time for
the encoder process was 1 microsecond (1e-06 is 1.x10^-6 in scientific
exponential notation). Since the encoded audio is 6.86 seconds long that
means that the encoder appeared to run at 6.86 million times realtime
(6.86e+06 is 6.86x10^6), or it encoded at a rate of 6.86 million seconds
of audio per second.

In this case the one microsecond measurement is likely very inaccurate
because of the short runtime relative to the timer resolution, so I
wouldn't trust this number. If you run it on a few minutes of audio
you'll get a more reliable runtime measurement.

> the Bitrate detail ‘without overhead’ and the Overhead figure 1.19%.

'without overhead' is the the average bitrate of just the compressed
Opus packets without any external framing. This is the number which
affects audio quality. It will generally be slightly less than the
requested bitrate if you supplied one, since opusenc tries to take the
container overhead into account.

The Overhead figure is the percentage of the actual output file taken up
by the containter formatting including framing, tag metadata, and
timestamps for seeking. 1% is a normal amount.

Hope that helps,

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