|
|
|
|
EAQUAL
EAQUAL (Evaluation of Audio Quality) is an ITU-R BS.1387 implementation
developed by the DSP engineer Alexander Lerch - the creator of the Compaact! AAC encoder.
The ITU-R BS.1387 standard aims to provide objective quality measurement
for compressed audio signals. Unlike subjective audio comparisons
(listening tests) that depend on each listener's auditory system, EAQUAL
mathematically models the same auditory system, therefore generating
consistent results across a broad spectrum of samples. As the author once
described, in the context of listening tests: "Perhaps you should think
of EAQUAL as _one_ listener whose results are not depending on his mood
and his concentration, who never gets tired and whose results are
repeatable."
The most relevant output of EAQUAL is the ODG (Objective Difference
Grade), a numeric value. An ODG of -4 means a very annoying disturbance,
while an ODG of 0 means that there is no perceptible difference between
the samples being evaluated. Wim Speekenbrink tested several samples on
several encoders (of that time, early 2002) and published the EAQUAL
results at his
web site.
Alexander stopped developing EAQUAL on February 2002 because of threats
from the patent owners, therefore version 0.1.3a, below, is the last
release.
Big thanks to Martin Wagner for reminding me of EAQUAL.
Date: 2002-02-06
Version: 0.1.3 alpha
Interface: Command line
Platform: Win32
Download: eaqual013.zip - 212kB
Sources: eaqual013.tar.gz - 384kB
|
|
|
|