[BUG] Opus output audio cannot be mono?

[TheJ]

Every time i try to encode the audio to opus mono but it always outputs to stereo no matter what, i tried doing the same thing but with ffmpeg and it works fine. Help..?

[Selur]

No debug output, no details, nothing to say from ne.

[TheJ]

No debug output, no details, nothing to say from ne.

sent you a pm

[Selur]

Looking at the debug output and the encoding call:

ffmpeg -y -threads 8 -loglevel fatal -nostdin -i "C:\Users\djoens\AppData\Local\Temp\iId_3_aid_0_lang_en_2021-07-30@09_46_42_1810_01.aac" -ac 2 -ar 44100 -f sox - | sox --multi-threaded  --temp "C:\Users\djoens\AppData\Local\Temp\2021-07-30@09_46_42_181001" --buffer 524288 -S -t sox - -t flac - | opusenc --bitrate 12 --comp 10 --framesize 20 --expect-loss 0 --max-delay 1000 --ignorelength -  "C:\Users\djoens\AppData\Local\Temp\iId_3_aid_0_lang_en_2021-07-30@09_46_42_1810_02.opus"

the downmix is missing in the 'sox'-part of the call.
-> I can reproduce the issue and will look into it after work today.

Cu Selur

[TheJ]

Looking at the debug output and the encoding call:

ffmpeg -y -threads 8 -loglevel fatal -nostdin -i "C:\Users\djoens\AppData\Local\Temp\iId_3_aid_0_lang_en_2021-07-30@09_46_42_1810_01.aac" -ac 2 -ar 44100 -f sox - | sox --multi-threaded  --temp "C:\Users\djoens\AppData\Local\Temp\2021-07-30@09_46_42_181001" --buffer 524288 -S -t sox - -t flac - | opusenc --bitrate 12 --comp 10 --framesize 20 --expect-loss 0 --max-delay 1000 --ignorelength -  "C:\Users\djoens\AppData\Local\Temp\iId_3_aid_0_lang_en_2021-07-30@09_46_42_1810_02.opus"

the downmix is missing in the 'sox'-part of the call.
-> I can reproduce the issue and will look into it after work today.

Cu Selur

Another question if you don't mind, i cant seem to get opus all the way down to 6kbps. I've seen handbrake do this and why can't Hybrid? Thanks.

[Selur]

I've seen handbrake do this and why can't Hybrid

That'S a bug, normally it should allow 6-256kBit/s per Channel, so for mono 6kBit/s should be possible.
-> will look into it

Cu Selur

[Selur]

Okay, found the problem, a typo caused the 'Mono'-downMix to be ignored, thus there was no downMix and and the bit rate limits weren't adjusted.
-> send you a link to a dev version via pm which should fix the issue, so once 'DownMix' is set to 'Mono' (or a mono source is loaded) opus should allow to set a bit rate of 6kBit/s.

Cu Selur