What is SoundExpert

Audio metric that makes a differenceSoundExpert (SE) is an independent non-commercial audio research project, which provides audio quality ratings of sound equipment and technologies such as mp3, aac, wma ... encoders and portable players (to be extended). It is the home for innovative music-based audio metric which works both for objective audio measurements and for listening tests. SE is in beta state because the new audio metric and corresponding listening test design are not widely adopted by audio engineers. So, please, use our ratings with caution.

The new listener-centric audio metric allows to perform objective audio measurements using real-life music material and various technical signals, not only sine waves. Such measurements:
• correlate well to human perception of sound quality
• are valid for digital audio
• do not contradict traditional audio metric but extend it
• are understandable to people without technical background
• can be performed at home using any recording device

The first practical application of the new measurement method can be found on the Portable players page.

The new listening test design helps to hear sound artifacts which are normally beyond threshold of human perception. The core of the new design is sound artifacts amplification technology (SARTAMP), which is backed by the new audio metric. Such amplification is particularly important for testing high-bitrate encoders and high quality audio equipment. This technology is used in SE listening tests since 2005. The tests are blind - participants don't know the particular device they assess. Resulting quality scores are completely unbiased and free from marketing and advertising noise.

Live Listening Tests @SoundExpertThe ratings of encoders are computed in real time while participants of the listening tests send their grades to the rating system. The more participants - the more devices and technologies can be tested. The testing procedure is simple and short enough that anyone, including you, can participate. Just download a test file (<3Mb), listen it (<15s) and send back your grade. Details are in the test file. The more accurate grades - the more reliable ratings.

Detailed but still easy to understand overview of SE distributed listening tests is in the paper Live Listening Tests @SoundExpert.

* * *

The main idea behind SoundExpert project is consumer control over sound quality of various audio equipment and technologies on the market. Production side deserves clearly defined feedback from consumers.

 

 

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Opus, AAC, Vorbis, MP3, MPC at 128 kbit/s

Opus, AAC, Vorbis, MP3, MPC at 128 kbit/s

Published Date 3/24/14 9:25 AM

This listening test has almost the same codec contenders as the previous @96 one with the following differences:

  • All encoders have integer/discrete quality settings which are normally used in practice; in other words, quality parameters were not adjusted to get equal resulting bitrates with nine SE test samples; so the test will show how these codecs with usual settings compare with each other; for codecs with close resulting bitrates some conclusions about their efficiency can be derived as well
  • Opus version was updated from 1.0.2 to 1.1 with some quality fixes
  • CoreAudioToolbox 7.9.8.2 for QuikTime encoder was updated to 7.9.8.3 without any quality improvements
  • AAC encoder by Fraunhofer from Winamp was updated from 1.04 to 1.08
  • New AAC encoder by Fraunhofer from Android Open Source Project was added
  • Musepack MPC was added

 

Resulting list of contenders:


AAC [email protected] (Winamp 5.666) - VBR, AAC LC

  • AAC Encoder v1.08 (Fraunhofer IIS) from Winamp 5.666: Variable Bitrate, Preset 4
  • The encoder is also available as CLI utility and can be downloaded from https://github.com/tmkk/fhgaacenc

AAC [email protected] (iTunes 11.1.3) - TrueVBR, AAC LC

  • iTunes 11.1.3.8 or QuickTime 7.7.4 AAC Encoder via qaac 2.30 (CoreAudioToolbox 7.9.8.3): qaac -V63 ref.wav
  • The encoder is included in such Apple products as iTunes, QuickTime, Safari; though not all of its features can be reached through these applications. For greater flexibility the CLI utility qaac can be used
  • download from https://sites.google.com/site/qaacpage/

AAC [email protected] (NeroRef 1540) - CVBR, AAC LC

Vorbis [email protected] (Xiph 1.3.3)

Opus [email protected] (libopus 1.1)

  • encode: opusenc --bitrate 96 ref48.wav (44.1/16 -> 48/24 by Audition CS6)
  • The encoder operates at 48kHz only, so for other sample rates (as in our case) resampling is required. Some good quality resampler is already integrated into the codec but we used the external one from Audition CS6; the complete test files production chain: reference test files 44.1/16 -->> 48/24(Audition CS6) -->> opusenc -->> decode by foobar2000(48/32) -->> 44.1/32(Audition CS6) -->> test files production
  • download from http://opus-codec.org/downloads/

mp3 [email protected] (Lame 3.99.5) - MPEG-1 Layer 3, VBR

AAC [email protected] (libfdk 3.4.12) - MPEG-4 AAC LC, VBR mpc [email protected] (SV8) - Musepack

 

In addition to usual live ratings on 128kbit/s page there will be detailed results of this test when corresponding ratings reach 1% accuracy (example of the detailed report is in the previous 96 kbit/s listening test).

***

SoundExpert reminds you that final conclusion about audio quality of any device added can be made only after finishing corresponding listening test. So we encourage you to take part in testing. SE ratings exist only thanks to visitors like you. Testing is short and easy, visit our Testing Room for simple 1-2-3 instruction.

Please, remember, downloading test files from SoundExpert you will not necessarily get the ones of the newly added codecs. SoundExpert testing is blind testing – you don't know the device you test. This is the only reliable way of getting true audio quality ratings, free from any cheating and various human senses other than perception of sound quality. After you have sent your grade you will see the device you tested.

Best regards,
SE Team.

By Serge Smirnoff
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