Libav Merges Its Native Opus Decoder

[psychoticmeow]

Last time I checked Opus supported only mono and stereo. More channels can be added in container but Opus won't use any correlation between them for compression, it only can compress channels in pairs. That's not good for movies.

Sounds like it supports it just fine then.

[mark45]

Last time I checked Opus supported only mono and stereo. More channels can be added in container but Opus won't use any correlation between them for compression, it only can compress channels in pairs. That's not good for movies.

What technical problem are you talking about? What's the correlation thing specifically?

[Nobu]

It's very clear that it was written from the belief that Opus will be as ineffective at gaining market share as Vorbis did.

Obviously. What's not so clear is why you are arguing with me about that point.

[TheBlackCat]

Sounds like it supports it just fine then.

It looks like some codecs intended for movies, like some or all versions of dolby, support correlations across multiple channels. This is probably important for surround sound for movies where there is likely a fair amount of redundancy across multiple channels. opus apparently doesn't support this as far as I can find.

[Daktyl198]

For music collection, it's better than mp3 but not that much when using a modern mp3 encoder at very high bitrates (>200), and it's not really better than AAC.
So in this industry, the transition will probably be much slower, if it ever happens.

The thing about opus, though, is that it sounds better at lower bitrates than mp3/AAC does at higher bitrates. Because of this, you can have audio files that sound just as good, if not better, at half the file size. This can be pretty important in places like portable audio players (iPods, etc) or even just for people who have a very, very large music collection (going from 10GB down to 5GB, with better audio quality is a pretty damn big change).

[Szzz]

What technical problem are you talking about? What's the correlation thing specifically?

If you have multichannel audio then there is probably a lot of similarity (correlation) between different channels, this similarity can be used for better compression. If you compress each channel separately then you will need to save same information several times. For 6 channel audio it would be better to compress all channels together but Opus can compress only 2 channels together.

[erendorn]

The thing about opus, though, is that it sounds better at lower bitrates than mp3/AAC does at higher bitrates. Because of this, you can have audio files that sound just as good, if not better, at half the file size. This can be pretty important in places like portable audio players (iPods, etc) or even just for people who have a very, very large music collection (going from 10GB down to 5GB, with better audio quality is a pretty damn big change).

AAC has similar quality to Opus for any reasonable music bitrate (> 48kb/s). It's true that both are quite better than mp3 for bitrates < 160kb/s. But then, Opus matches AAC while being free, so if you don't mind the (for now) limited player support, it is indeed a good solution for encoding your music collection.

But 10GB does not look large to me :P