Re: Opus 1.3-rc
Reply #22 – 2018-06-07 22:39:48
I'd listen to a 9kbps Opus audio without complaining as far as speech goes... 14kbps is about the lowest I would suggest as while you can go lower and have it still passable (i.e. still understand what's said etc) I feel sound quality starts to really drop off going below the 14kbps setting, at least based on my Klipsch Pro-Media speakers for the PC. because while I can notice the 14kbps being a hit to the overall sound compared to the 128kbps original MP3 speech file I got, it's not that much worse for a tiny fraction the original files bit rate. basically I sort of feel 14kbps, for speech, is that sweet spot where one wants smallest possible file size but without sacrificing sound quality too much. I know the 'sweet spot' might vary from person-to-person though as some might favor sound quality over bit rate a bit and some might be more of the other end where they favor super small file size at the expense of sound quality but I suspect many would find my suggested 14kbps as solid enough as while you can definitely notice the difference in sound drop off, it's not that much considering the really low bit rate. NOTE: I have not messed with Opus v1.3RC much yet but I suspect things will remain the same on what I said above.I hope there'll be improvements at 32 kbps and less artifacts at low bitrates. If I recall correctly, from what I have read around here not long ago, it seems like there will be mainly adjustments in the 48kbps and lower ranges as I would not expect much, if anything, on about 64kbps and probably next to nothing, if not nothing, in the 96kbps+ ranges since 96kbps is already pretty darn good given the listening tests around here. but even assuming what I said above is correct... I would imagine we are talking very small differences in sound quality to where when casually listening I would not expect to hear any obvious differences between v1.2.1 and v1.3RC at bit rates of 32-48kbps (give or take). so basically what I am saying is, don't expect much as I doubt there will be any obvious differences from v1.2.1 to v1.3 as we are probably talking faint differences I would imagine for the most part. while adjustments at the really low bit rates are nice, personally, I would like to see how far they can lower the bit rate while still 'approaching transparency' (or close enough to that standard) when it comes to music. so in this regard, while 96kbps is pretty much that 'approaching transparency' level already with Opus v1.2.1 it would be nice if that could be lowered a bit to say improve 64kbps (and the like) as I imagine much under 64kbps is just going to be difficult to get near that standard and even 64kbps is probably asking a lot already given it's a 1/3rd less bit rate than the already strong 96kbps, which is already a pretty low bit rate. but with that said... it seems Opus is already a pretty strong performer at those low bit rates (say under 96kbps) as say something like 10-15 years ago the sound quality Opus has at 64kbps was overall better than bit rates quite a bit higher than that. so it's obvious they (general audio encoders) made fairly major progress since then. but it's nice in that, at least with AAC/MP3, any files encoded in this decade (assuming the person used the newest encoders at the time) you don't have to worry about sound quality since it's pretty much the same. but in the previous decade as the years passed they made solid progress as the years passed. but this might not entirely apply to Opus given that seems to have made decent progress in this current decade where as AAC/MP3 peaked something like 8-ish years ago(?).