Public Multiformat Listening Test @ 48 kbps (November 2006)

After the last public AAC listening test @ 48 kbps conducted by Gabriel Bouvigne, it is time for a multiformat test at 48 kbps featuring the latest and greatest encoders optimized for this bitrate, including the long-awaited WMA Professional 10 codec shipped with Windows Vista and Windows Media Player 11.

While most contenders use VBR encoding, WMA Professional 10 has to be tested using CBR because no VBR quality setting comes near 48 kbps.

• Which codecs and settings are tested?

  • iTunes AAC 7.0.2.16 (High Anchor)
    96 kbps, VBR
  • Ogg Vorbis AoTuV 5 Beta
    -q -1
  • WMA Professional 10
    1-pass CBR, 48 kbps
  • Nero HE-AAC May 26 2006
    -q 0.2
  • WMA Standard 9.2
    Quality-Based VBR, Q10
  • iTunes AAC 7.0.2.16 (Low Anchor)
    48 kbps, CBR

• Is it normal that the bitrate is very high on some samples (even 73 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 48 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:

  • ABC-HR_bin.zip

  If you already have ABC/HR, download the readme from here:

  • readme.txt
  • readme.htm

  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 1.4 can participate (JRE 1.5 is recommended, though). Instructions are available inside the ABC/HR package.

• When will the test finish?

  The test is scheduled to end on December 8th, 2006. This date may be extended if proven to be necessary.

  Update: The results are now available here.

If you have any questions, feel free to contact me via e-mail: mail@listening-tests....

Best regards,
Sebastian Mares

© Sebastian Mares, 2006 | Layout by Dibrom | Portions of the Text by Roberto Amorim