General discussion of future public test Options

[IgorC]

Hello,
Now when it’s sure that Apple encoder represents AAC standard very well the next step will be a public multiformat test.
No particular date or plan. It’s a general discussion with the purpose to hear the opinions, points of view, suggestions.

Items to talk about (these numbers are first approximations):
1.The number of codecs: 4+low anchor. 4 is affordable number for one test.
2.The selection of codecs (basing on curret previous votes):
http://listening-test.blogspot.com/2011/06...reparation.html

Apple LC-AAC - the most optimal AAC encoder. (Well, though FhG was quite good too).
MP3 LAME – 10 votes
Vorbis AoTuV – 8.5 votes.
Opus/CELT – 6 votes. (still no info when there will be Opus 1.0)

It’s possible to change your votes.

(?) USAC (working name of future AAC’s successor ). No information about future availability of it.
(?) low anchor
(?) Settings, versions, etc.

3. Bitrate:
VBR 96 kbps. The last AAC public test was at 96 kbps (well, it was actually 100 kbps).
Also I think it will be more interesting to compare MP3 128-135 kbps and AAC/AoTuV 96-100 kbps. Probably a lot of people are interesting to trade off between compability/compression efficiency

4. Samples.
Last time we have applied the technic of random selection of the samples. 20 samples.

The developers are very welcome to participate in this topic.

This test should be more interesting as it will include interesting (for use) codecs.

[halb27]

The fact that Lame resamples to 32 kHz at 96 kbps shouldn't worry too much IMO. Maybe the lack of HF is easily noticeable, but at 96 kbps there is worse to be frightened of for mp3. Lacking the extreme frequency range doesn't really hurt much though it's often audible.

Whether it's useful that mp3 participates in a 96 kbps test is a question of sample selection. With problem samples, especially pre-echo stuff, mp3 won't have a chance, and participance of mp3 doesn't make sense.
So if mp3 should participate we'd better use only regular music, best chosen by chance.

On the other hand I wouldn't mind if we forget about mp3 at 96 kbps. It's really no candidate for the winner here.

This post has been edited by halb27: Dec 23 2011, 16:39

[nu774]

The fact that Lame resamples to 32 kHz at 96 kbps shouldn't worry too much IMO. Maybe the lack of HF is easily noticeable, but at 96 kbps there is worse to be frightened of for mp3.

QuickTime at CVBR96k surely doesn't do sample rate conversion by default, but LPF at 15k-16k or so is applied anyway. AFAIK FhG @ VBR q3 do the same.
In other words, "losing highs" is neither specific to LAME nor important.

As for QuickTime true VBR mode, sample rate conversion to 32k is done at quality 54 by default.
Therefore, when the test is done at quality 54, the decision must be made also for QuickTime, whether to use sample rate conversion or not.

This post has been edited by nu774: Dec 23 2011, 17:55