Although it would be nice, I doubt anyone will be using USAC for ripping this year Chris
Quote from: C.R.Helmrich on 02 January, 2012, 10:52:27 AMAlthough it would be nice, I doubt anyone will be using USAC for ripping this year ChrisWill USAC be better than HE-AAC?
Will USAC be better than HE-AAC?
Quote from: Gainless on 03 January, 2012, 07:40:53 AMWill USAC be better than HE-AAC?At low bit-rates, yes, as Igor has shown. At "ripping bit-rates" of > 96 kbps (no SBR), only on very few audio samples.Chris
Thanks for the answer Chris. Can you give a rough evaluation already how far the improvements will go, e.g how good the codec will compete with AAC around 96 or 128 kbps in terms of sound quality?
Quote from: Gainless on 05 January, 2012, 08:21:46 AMThanks for the answer Chris. Can you give a rough evaluation already how far the improvements will go, e.g how good the codec will compete with AAC around 96 or 128 kbps in terms of sound quality?Assuming carefully tuned encoders, at 128 kbps or so, USAC w/o SBR will give about the same average quality as AAC-LC. My guess is that some killer items will sound a bit better (~ 5 MUSHRA points), and none will sound worse with USAC (guaranteed since USAC transform coding is very similar to AAC).Chris
As far as I know USAC has reached the final state as format/standard (at last it's final draft).
Also it should be clear that USAC uses improved but still parametric bandwidth extension (enhanced SBR: eSBR) at bitrates up to 80 kbps. It means USAC is/should be/will be better than HE-AAC but parametric tools like SBR (even enhanced version of it ) loose completely their advantage over LC-AAC and USAC without SBR at bitrates >~80-85 kbps.
USAC brings bitrate reduction of about 10% (maybe a bit more or a bit less. Will depend of impelementations, material etc.) at range of bitrates 64 kbps and higher. The efficiency gain is considerably higher than that for lower bitrates (less than 64 kbps).
The main goal of USAC wasn't to bring much superior compression gain but provide equally high quality for both speech and music.
When we did internal tests to prepare for the verification tests, we compared USAC with and without SBR at 96 kbps. They were on par. This is possible because due to increased core-coder efficiency (as you mentioned) a higher SBR cross-over frequency can be chosen at higher bit-rates. For some items (e.g. some speech or tonal items without transients) SBR is better than no SBR even at 80-85 kbps.
I'm pretty sure that USAC's SBR and no-SBR are on par at lower bitrates as well, let's say 80 kbps. (in the same test conditions)
Quote from: IgorC on 05 January, 2012, 04:41:44 PMI'm pretty sure that USAC's SBR and no-SBR are on par at lower bitrates as well, let's say 80 kbps. (in the same test conditions) I'm sure they are not We'll see once we've tuned our USAC encoder to the level of the HE-AAC encoder in, say, Winamp.