OPUS wizard: CBR/VBR and small bitrates

[PhoenixIV]

I just checked the wizard for OPUS and two things came up:

First, I can only choose CBR from a dropdown menu, but can then, additionally, tick VBR. This works fine, no major issue, but makes no sense.

More important (even though this can easily be solved by altering the generated parameters code): The lowest accepted bitrate is 64 kbps. But, especially with OPUS, bitrates like 32k (and lower!) are still common / producing great results.

The default suggested compression level is 5 if I am not wrong. The pre-set in the wizard is 10.

[eibol]

Hi, I will include these suggestions on next release.
Regarding VBR, ffmpeg results vary depending on the combination of bitrate and vbr choices.
If only vbr is selected, bitrate is always low, and quality factor affects the encoding complexity and speed, but not output bitrate that much.
If you select only cbr, you obtain the desired bitrate, but if you add -vbr on and a -compression_level n, bitrate also changes a little bit, as well as the encoding speed. So it seems that vbr can work either alone or with a target bit rate.

[PhoenixIV]

The default suggested compression level is 5 if I am not wrong. The pre-set in the wizard is 10.

I gave wrong information here. Default is 10.
Source: https://wiki.xiph.org/index.php?title=Opus_Recommended_Settings#Trading_Coding_Efficiency_with_CPU_Time

[eibol]

Right. I'll revert the default compression factor to 10 for next release, coming out by the end of this month.

[PhoenixIV]

Yeah. Sorry. Thank you, @eibol ❤