PEXQ

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PEXQ is a collection of algorithms for the objective measurement of the perceived quality of communication channels and an associated software suite from OPTICOM GmbH to work with. The algorithms are in detail

• Perceptual Evaluation of Audio Quality (PEAQ),
• Perceptual Evaluation of Video Quality (PEVQ),
• Perceptual Evaluation of Speech Quality (PESQ, developed for telephone connections) and
• Perceptual Evaluation of Data Download Quality (PEDQ).

In a comparison of the starting material and the product that is available at the end of the transmission chain, various objective criteria are individually assessed and a Mean Opinion Score (MOS) between 0 (imperceptible) and −4 (very annoying) for the perceived quality or the disturbances generated by the examined method are averaged. As an automatic procedure, the test procedures are intended to represent a cost-effective alternative to complex tests based on the subjective judgments of human test persons. Accordingly, they are each based on a model of human perception and the quality of their results is assessed in comparison with the results that can be achieved with human test subjects. Normally, natural signals are used to measure.

Perceptual Evaluation of Audio Quality (PEAQ)

PEAQ is recommended as BS. Standardized in 1387 by the International Telecommunication Union (ITU). It was developed by the ITU-R Task Group 10/4, which was founded in 1994 for this purpose and concluded its work in 1998 with a proposal for a measurement method standard. The standard was last updated in 2001.

The method works with a ( psychoacoustic ) model of human hearing with FFT and filter bank-based parts. Parts that represent the outer part of the hearing are based on older methods such as PERCEVAL (Perceptual Evaluation), POM (Perceptual Objective Measure) and OASE (Objective Audio Signal Evaluation).

The process is covered by several patents and license fees are charged for commercial use. There are independent implementations such as PQevalAudio and Peaqb that have not been checked by the ITU and can be used free of charge for teaching purposes.

Perceptual Evaluation of Video Quality (PEVQ)

PEVQ is based on factors such as the signal-to-noise ratio depending on the motion of the picture, picture brightness and contrast, delay (to the reference signal) and possibly synchronicity with an (optional) audio track. PEVQ was proposed for standardization among other candidates and, after review by the Video Quality Experts Group (VQEG), then part of ITU-T recommendation J. 247 , which represents the international standard for measuring perceived video quality.

Perceptual Evaluation of Speech Quality (PESQ)

PESQ is standardized as Recommendation P.862 (02/01) of the ITU-T and represents an industry standard used worldwide. It replaces the previous ITU-T standard P.861 (Perceptual Speech Quality Measure, PSQM) and is intended as such itself be replaced by the Perceptual Objective Listening Quality Analysis (POLQA), which is in the drafting stage.

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1. ↑ http://elvera.nue.tu-berlin.de/files/0829Thiede1998.pdf
2. ↑ http://publica.fraunhofer.de/dokumente/N-61398.html
3. ↑ Archived copy ( Memento of the original from August 27, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
4. ↑ Archived copy ( memento of the original dated July 6, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.