This Recommendation describes the video module as an integral part of the ITU-T P.1203-series Recommendations. The ITU-T P.1203 Recommendations describe a set of objective parametric quality assessment modules. Combined, these modules can be used to predict the impact of audio and video media encodings as well as Internet protocol (IP) network impairments on the quality experienced by an end-user of multi-media streaming applications.

The addressed streaming techniques comprise progressive download as well as adaptive streaming, for both mobile and fixed network streaming applications over transport control protocol (TCP) or other TCP like protocols which are not affected by transmission errors.

The model described is restricted to information provided to it by an appropriate packet- or bitstreamanalysis module. The overall ITU-T P.1203 model is applicable for the effects due to audio- and video-coding as well as initial loading delay or stalling (which are both caused by rebuffering at the client) as the typical degradations associated with progressive download. As final output, the ITU-T P.1203-series models target integral audiovisual media quality scores.

This Recommendation describes four different quality modules, one for each mode of ITU-T P.1203, that is, modes 0, 1, 2 and 3. The video quality module predicts mean opinion scores (MOS) on a 5-point ACR scale (see [ITU-T P.910]) as a per-one-second MOS score. The underlying measurement window is described in [ITU-T P.1203]. If used stand-alone, the video module can provide estimates of short-term video quality at per-one-second intervals.

This model cannot provide a comprehensive evaluation of video transmission quality as perceived by an individual end user because its scores reflect the impairments due to video scaling, framerate and coding only. Furthermore, the scores predicted by a parametric model necessarily reflect an average perceptual impairment.

Note also that the model was developed and validated for one specific encoder and decoder implementation. If a different encoder and decoder pair is used in a monitoring situation the scores may not reflect that.

Effects such as flicker due to low source bitrate or other, not coding or transmission caused impairments related to the payload are not reflected in the scores computed by this model. Moreover, the scores predicted by a parametric model (especially in case of no access to payload or pixel information) necessarily reflect a somewhat simplified representation of the perceptual impairment of the considered stream.

However, the model still enables estimation of some coding quality related information and thus valid and in most cases accurate predictions, presuming that it is applied in an appropriate manner, following this Recommendation.

Table 1-1 shows application areas, test factors and coding technologies where ITU-T P.1203.1 for adaptive streaming and progressive download has been verified and is known to produce reliable results.