Opus 1.1a BABYEATER build Options

[NullC]

Ever mindful of the world's population problems, the Opus development team is excited to present a new highly experimental build of Opus which is expected to eat 100% more babies than prior editions. It is also expected have (potentially) improved transient handling performance:

https://people.xiph.org/~greg/opus-tools_ba...ater-deluxe.zip (Edit: replaced with updated version, see below)

What this does is adapts the frame-size dynamically based on transient analysis prior to encoding. Leave the opus-tools framesize knob alone (in this test build it controls the amount of look-ahead used for the analysis, and 60ms is the default and only tested value).

It would be super-helpful to compare this with the regular 1.1 alpha at various rates and point us to any interesting results you find (e.g. where it does obviously worse or better, or where it catches fire and/or eats household pets instead of babies). Obviously you shouldn't be encoding your music archives with this stuff yet.

This post has been edited by NullC: Feb 13 2013, 01:07

[RobertM]

I'm not a listening expert. However, I was interested in seeing how the progress made in Opus has progressed over the last few months. Using the latest code from opus-tools (from git://git.xiph.org/opus-tools.git ) I compiled the binary, obtained the the three previously-worst Opus samples from the hydrogenaudio listening test and re-encoded the lossless samples at 64kb/s.
http://people.xiph.org/~greg/opus/ha2011/

The samples chosen were numbers 1, 2 and 26. Here are the results of my (unofficial) ABX listening test.

Sample 1 - Acoustic guitar solo:
In the original Opus encoding there was quite a bit of distortion on the guitar notes. It was very noticeable and was significantly worse than the lossless version.

With the new opusenc, the distortion virtually disappeared. I could still just barely differentiate between the lossless and opus versions of the file, but it was very close to a perfect score.


Sample 2 - Harpsichord solo:
There is a large amount of distortion on the harpsichord notes in the original encoding.

Again, with the new opusenc the distortion disappeared. Similarly to sample 1, could just barely tell the difference between the opus-encoded version and the lossless one.

Sample 26 - Guitar mix (acoustic and electric):
In the original opus encoding, the acoustic guitar sounds very tinny and the electric guitar loses some depth.

I wasn't able to tell the difference between the new opus version and the lossless version.

Conclusion
My amateur conclusion is that the latest version of the encoder (af25999bbd6aef6defcefebd489e1cf4abbcd867, 2013-02-25) fixes some significant issues which were causing distortion in some samples encoded with the version used for the listening test (CELT 0.11.2, March 2011).

I didn't test further to see whether the previously good samples had regressed at all. It would be interesting to see the results of another listening test take place once the Opus encoder v1.1 is officially released.

This post has been edited by RobertM: Feb 25 2013, 12:18