BS.1387

ITU-R recommendation BS.1387 is the document that defines Perceptual Evaluation of Audio Quality (PEAQ), an objective measurement technique used to measure the quality of encoded/decoded audio files. It acts in contrast to more the common place subjective testing methodology deployed using ABX and ABC/HR reference testing -- frequently preferred by hydrogenaudio. PEAQ returns an "ODG" rating, which is intended to match the difference in subjective (1–5) scores between the two input samples.

EAQUAL (Evaluation Of Audio Quality) is an open-source software that implements PEAQ. Several tests have been performed using EAQUAL most notably using numerous AAC encoders to determine via a Pearson Correlation the linear relationship between human ratings and EAQUAL ratings on a given set of test samples. The results, however when using objective testing methodologies are still inconclusive and mostly only used by codec developers and researchers.

Testing Using EAQUAL

As of version 0.1.3alpha, the -h argument can be used to find out how to use eaqual (ex: eaqual -h).
To compare a test wave file to a reference wave file, one can use for example: eaqual -fref ref.wav -ftest test.wav.

Interpreting the Results Output by EAQUAL

The results of EAQUAL are interpreted using what is known as an ODG score. Note: this information needs to be expanded.

External links:

• EAQUAL Sourcecode linux archive of c code used to implement EAQUAL provided by Gabriel Bouvigne.
• EAQUAL Tools zip compression archive of the utility used to perform EAQUAL tests provided by Rarewares.