Yalac - Comparisons, How the evaluation release compares to other compressors Options

[TBeck]

Content

In this thread the testers should post comparisons of the preset modes of Yalac (Working name for "Yet another lossless audio compressor") with other lossless compressors.

The results for specific variations of individual encoder options should go into the thread " Yalac – Evaluation and optimization".

Guidelines

Please post the exact version number of the compressors. Compression ratio should be specified in percent of the uncompressed file size. Speed figures should be specified as multiple of real time (duration of the test files). A specification of your test system, especially the CPU, would be helpful.

Open end: Feel free to add more results later.

What happened

Bad timing of my introduction (April 1.) forced an early publication of an evaluation release of Yalac, to prove, that it really works. This are results of 8 forum members, who where so kind to test the experimental release for me.

Many thanks!

Goals

Yalac should finally achieve compression ratios on par with Monkey's Audio High. Decoding speed should be at least two times higher than Monkey and never be significantly lower than with FLAC (possibly Yalac will later be integrated into FLAC).

My next steps

The first results i have received from the testers show me some weaknesses of the encoder. That's a good thing, because that means, that there definitely is a chance to increase the compression efficiency! Same is true for the speed; especially the decoder is not fully optimized yet. But it will take some time, before i will come up with an optimized release.

Links to 24 bit files i have used

I think, they are hard to find.

CODE

44 KHz, 24 bit

mytek_8X96_24bit_web.wav
Mytek-stereo96adc_evans.wav
Mytek-stereo96adc_ravel.wav

Source: http://www.mytekdigital.com/compare/comparison1.htm

48 KHz, 24 bit

McDougalsMen24bit_48kHz.wav
sister24bit_48kHz.wav

Source: http://ff123.net/samples.html

Or make a better Google search. foosion shows you how: http://www.hydrogenaudio.org/forums/index....ndpost&p=381702

This post has been edited by TBeck: Apr 12 2006, 20:23

[Synthetic Soul]

I'm not sure what the priority is for testing 0.06. Would we be comparing against other encoders, or is the idea that we simply run Yalac on numerous files using all its presets?

I'm quite happy to pass some batch files on if it will help people test, but I'm not sure the database I used in my initial test is adequate for this round of testing.

The way I see it, if we are simply testing how Yalac performs, we need to test a greater variety of files (mono; 24bit; etc). The database is only really set up to deal with 44.1KHz 16bit stereo files. If you consider what my pages detailed, it would really just be a table to show that fast is faster than normal, and high compresses better than normal. We know that already (well, we can assume).

Don't get me wrong, I think amalgamating the results is a great idea. Joseph Pohm and I have communicated regarding a similar thing. I think I'm being a little short-sighted and just need some help to understand how and what we would all be testing.

[TBeck]

I'm not sure what the priority is for testing 0.06. Would we be comparing against other encoders, or is the idea that we simply run Yalac on numerous files using all its presets?
...
The way I see it, if we are simply testing how Yalac performs, we need to test a greater variety of files (mono; 24bit; etc). The database is only really set up to deal with 44.1KHz 16bit stereo files. If you consider
...
Don't get me wrong, I think amalgamating the results is a great idea. Joseph Pohm and I have communicated regarding a similar thing. I think I'm being a little short-sighted and just need some help to understand how and what we would all be testing.

To be honest, i don't have an elaborated plan for test design beyond my current interests.

I did work on

- mainly speed optimizations
- improvements of my source code quality
- some slight compression improvements (found some opportunities while evaluating my source code).

Hence current tests should check

a) if the speed optimizations are present on different platforms (especially CPU's)
b) if the speed and source code optimizations didn't affect the reliability
c) if the changes made for the slight compression improvements don't hurt on other files.

For this purposes an evaluation based upon the existing test sets and a comparison with previous results would be quite helpful. For a) and b) the tests sets don't have to be really representative.

Most work for V0.07 will probably again consist of speed optimizations of the channel decorrelation. V0.06 brings algorithmic, V0.07 will bring assembler optimizations.

Reason: I want to improve the channel decorrelation in terms of compression efficiency. The current speed optimizations should guarantee, that later increases of the algorithm complexity will not hurt speed too much. And i really like Yalac to be fast...

V0.08 should contain an improved channel decorrelation. Then it will be really useful to test it on heterogenous file sets to tweak it. Mono and 24-Bit files wouldn't be important here.

Besides testing for my development purposes i am surely interested into comparisons with other compressors! Why else should i look for some tenth of a percent better compression...

I hope this shows some direction for possible further testing.

Thomas

P.S.: Some time in the future i will activate my ominous pre filter, which gives up to 4 percent better compression on some rare problem files! But this one needs really much evaluation on big test sets.

This post has been edited by TBeck: May 5 2006, 22:24