64kbps public listening test, FINISHED Options

[rjamorim]

Hello.

There have been some delays, but here are the so awaited results of the latest 64kbps group blind listening test.

http://audio.ciara.us/test/64test/results.html

And the final plot:
Each vertical line segment represents the 95% confidence interval (using ANOVA analysis) for each codec.


Note: Lame MP3 is 128kbps "high anchor" in this test, FhG MP3 is the "low anchor"

Zoomed version without the anchors:


Codec specifications:

• Ahead/Nero 6.0.0.15 HE AAC VBR profile Streaming :: Medium, high quality
• Ogg Vorbis post-1.0 CVS -q 0
• MP3pro (from Adobe Audition 1.0) VBR quality 40, Current Codec, allow M/S and IS, allow narrowing, no CRC
• Real Audio Gecko (from Real Producer 9.0.1 64kbps
• Windows Media Audio v9 VBR quality 50
• QuickTime 6.3 AAC LC 64kbps, Best Quality
• Lame MP3 encoder 3.90.3 --alt-preset 128 --scale 1. (high anchor)
• FhG MP3 encoder (from Adobe Audition 1.0) 64kbps CBR, Current codec, allow M/S, no I/S, allow narrowing, no CRC. (low anchor)

Thanks to everyone that participated and helped!

Best regards;

Roberto.

[[proxima]]

This is the table of my results:



According to the averege the best my preferred encoder seems to be HE AAC even if i should say that i’m quite surprised for the result of mp3PRO (or maybe i’ve overestimated HE AAC).

I’ve done a sort of ranking for the best, real antagonists at 64 Kbps. The first position is colored in green, the second in yellow and the third in red. With this direct comparison Mp3PRO is (according to my preferences) often better than HE AAC.

Mp3Pro has shown a detectable lowpass (16Khz) but this is not the real problem for a 64 Kbps, artifacts are more annoying. There is an interesting thing i’ve perceived: with HE AAC the high frequencies seem unnatural, attenuated, as if it was lowpassed. While doing the blind test i imputed this to the lowpass, but later i’ve discovered that the HE AAC files are lowpassed at about 20 kHz (surely inaudible for me). Does FAAD use dithering when decoding ? If not, i think that the fact could be explained with the SBR “problem” of which guruboolez give us an excellent description.

While the two codecs above scored a very close quality level, i can’t say the same for Vorbis that is often behind the others two. I surely agree with guruboolez: Vorbis in this bitrate range is easy detectable because of noise and exaggerated highs (with sharp attacks the result is quite annoying).
We all are waiting for the 1.1 version that should give better result with this type of artifacts.

At the end, i sincerely want to thank Roberto for his effort organizing this useful test. The number of participants is increased and this is a clear indication of good organization.