[FFmpeg-user] libopus encoder produces bigger files than opusenc with 6-channel audio

Peter White peter.white at posteo.net
Mon Jul 18 20:59:45 EEST 2016

Am 18.07.2016 um 18:51 schrieb Carl Eugen Hoyos:
 > Peter White <peter.white <at> posteo.net> writes:
 >> So both programs autoselect 320 kbit/s as the nominal
 >> bitrate, yet opusenc produces a considerably smaller file.
 > So you are reporting a bug in opusenc on our mailing list?

I was merely checking if there was a bug to be found or if ffmpeg did
something differently than opusenc.

 > In any case: If the default bitrate is 320k for your
 > usecase (I didn't check, you claim so) and FFmpeg
 > produces an output file closer to this bitrate than
 > opusenc, there is no bug in FFmpeg.

Is this really how it works with opus? As I understand it, that
bitrate setting results in an average of i.e. 320k over a "typical
music collection"[1], so in a single file it may be below or above the
target, depending on the content. What you might be thinking about is
constrained vbr, or cvbr, which is supposed to be like abr in LAME or
managed mode in vorbis.

Anyway, I now know what the reason for the discrepancy was.

[1] http://wiki.hydrogenaud.io/index.php?title=Opus#Characteristics


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