Re: Opus 1.2 alpha
Reply #49 –
I wonder which codec is being used with --bitrate 32 --framesize 60 --cvbr --downmix-mono setting right now in 1.2-alpha. Seems like a nice spot for very low bitrate generic music. It's still noticable not transparent, but artifacts are not utterly annoying (at least compared to HE-AACv1 mono at this bitrate). For me it's even listenable with headphones on. But it sounds a bit different, like it was using SILK instead of CELT.
Not closely related, but is there any algorithm which can more gracefully downmix stereo to mono in order to avoid phase cancelation as much as possible? Does Opus involves anything like that with --downmix-mono, or it's just using a simple downmix algorithm? Imo below 48kbps Opus is not capable enought to represent stereo without nasty artifacts at the moment (especially bad when played back on single speaker devices, like mobile phones), so I'm preferring the mono downmix. But that's just my 2 cents. Maybe reducing the stereo width and phase significantly before encoding could help, but then again, you can just downmix to mono then.