Public Multiformat Listening Test @ 64 kbps (July 2007)
After my last public multiformat listening test @ 48 kbps, it is time for a multiformat test at 64 kbps featuring the most up-to-date encoders optimized for this bitrate, including WMA Professional 10, HE-AAC and Ogg Vorbis. It is also interesting to see if Microsoft's claims regarding the superiority of WMA Professional 10 over HE-AAC (see link below) are still valid.
While most contenders use VBR encoding, WMA Professional 10 is tested using CBR because it seems to be the setting recommended by Microsoft (according to a test by Microsoft and NSTL).
Which codecs and settings are tested?
iTunes AAC 220.127.116.11 (High Anchor)
96 kbps, VBR
Ogg Vorbis AoTuV 5 Beta
WMA Professional 10
1-pass CBR, 64 kbps
Nero HE-AAC Jul 20 2007
iTunes AAC 18.104.22.168 (Low Anchor)
48 kbps, CBR
- iTunes AAC 22.214.171.124 (High Anchor)
Is it normal that the bitrate is very high on some samples (even 89 kbps)?
Yes, and that is the beauty of VBR encoding - it will simply ignore bitrate limitations whenever possible, using as much bits as needed to encode a problematic sample.
Although that raises issues of fairness, it is the best way to compare modern codecs that shine most in VBR mode, like Vorbis. Trying to force a VBR setting to match a desired bitrate, although fairer, is far from the usual practice of audio encoding, where it's more usual that a user just sticks to a quality setting, not caring much about a specific bitrate.
The quality settings for the VBR codecs were chosen because they average out to about 64 kbps over a number of encoded albums. It would be unfair to tie the hands of VBR codecs and punish them for being smart about where to spend what turns out to be the same number of bits over the long run.
Who should take the test?
Anyone interested in lossy audio quality, or people who have no interest but would like to help making this test better are invited. You don't need excellent hearing, but some good gear is welcome. Using headphones is encouraged.
How do I take the test?
Download ABC/HR and the readme from the following location:
If you already have ABC/HR, download the readme from here:
Further instructions and links to the sample packages are inside the readme.
Please note: if you don't hear any sound when using ABC/HR, simply change the device from ABC/HR's settings. In some cases, ABC/HR might not default to the primary audio driver.
Can I take the test even if I am not running Microsoft Windows?
Thanks to schnofler, any person running an operating system with Java Runtime Engine 1.5 can participate. Instructions are available inside the ABC/HR package.
When will the test finish?
The test is scheduled to end on August 5th, 2007. This date may be extended if proven to be necessary.
Update 1: The test was extended to end on August 12th, 2007.
Update 2: The test was extended to end on August 15th, 2007.
Update 3: The partial results are now available here.
Update 4: The final results are now available here.
If you have any questions, feel free to contact me via e-mail: email@example.com.
© Sebastian Mares, 2007 | Layout by Dibrom | Portions of the Text by Roberto Amorim