[opus] Q: Bandwidth vs. bitrate

[Ulrich Windl]

Hi!

So here is what I got with different encoder settings; still not sure what the "best" setting is. 6kbps seems to add distortions, so I tried 12kbps.
MP3-Original: LAME 3.99r, 120kbps, 44100Hz, Stereo, VBR V5 (22:23, 19.8MB)
Opus (--raw-rate 44100 --bitrate 56 --vbr --comp 5): (44:45?, 23.4MB): Broken
Opus (--bitrate 56 --vbr --comp 5 --ignorelength - %d): (22:23, 12.1 MB, 74kbps)
Opus (--bitrate 6 --vbr --comp 10 --ignorelength - %d): (1MB, 6kbps)
Opus (--speech --set-ctl-int 4008=1103 --bitrate 56 --vbr --comp 5 --ignorelength - %d): (22:23, 9.3 MB, 74kbps)
Opus (--speech --set-ctl-int 4008=1103 --bitrate 6 --vbr --comp 5 --ignorelength - %d): (22:23, 1.1 MB, 74kbps)
Opus (--bitrate 12 --vbr --comp 5 --ignorelength - %d): (2.1MB, 13kbps)
Regards,
Ulrich

>>> Mathias Buhr 30.10.2019, 14:39 >>>
Hi Ulrich,
I assume you've been using opusenc to encode the files. If that is the
case you can try giving the encoder some more hints about your files:
opusenc --speech --set-ctl-int 4008=1103 ...
The latter should tell the encoder that the signal bandwidth is 8kHz
(OPUS_SET_BANDWIDTH). See opus_defines.h for all valid numbers. You can
also experiment with the complexity settings.
-Mathias
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