Public Multiformat Listening Test @ ~64 kbps (March 2011)

There has been significant advancement since the last 64kbps test. The Nero HE-AAC and Aoyumi Vorbis encoders improved, Apple added HE-AAC capability, and we have a new low delay codec: CELT.

The test is finished, results are available here.

• Which codecs and settings are tested?

  • Nero 1.5.4.0 HE-AAC
    -q 0.245
  • Ogg Vorbis AoTuV 6.02 Beta
    -q 0.1
  • Apple QuickTime 7.6.9 HE-AAC
    constrained VBR, high quality, 64 kbps
  • CELT 0.11.2 (March 2011) http://www.celt-codec.org/
    complexity 10, VBR 67.5 kbps
  • iTunes AAC 7.6.9 (Low Anchor)
    48 kbps, CBR

• Is it normal that the bitrate is very high on some samples (even 128 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:

  ABC-HR.zip

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

  readme.txt

  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.

• When will the test finish?

  The test is scheduled to end on 30th March, 2011. This date may be extended if proven to be necessary. The test is extended until the 10th of April.

  The test is closed!

• Where can I download the encoders?

  • CELT: https://people.xiph.org/~greg/celt-0.11.2-win32.zip
  • Nero HE-AAC:
    http://www.nero.com/eng/downloads-nerodigital-nero-aac-codec.php
  • Vorbis aoTuV: http://www.geocities.jp/aoyoume/aotuv/
  • Apple (HE-)AAC: http://www.apple.com/itunes/

If you have any questions, feel free to contact me via e-mail: igoruso@gmail.com.

Best regards,

© Sebastian Mares, 2007-2011 | Layout by Dibrom | Portions of the Text by Roberto Amorim | Edited by Igor