ITU-T J.343.4 PDF

This Recommendation¹ describes algorithmic models for measuring the visual quality of IP-based video services.

The models are hybrid-reduced reference (Hybrid-RR) models, which use features extracted from the unimpaired reference video signal, the non-encrypted bitstream data and the video image data captured at the video player.

As output, the models provide an estimate of visual quality on the [1,5] difference mean opinion score (DMOS) scale, derived from five-point absolute category rating (ACR) as in [ITU-T P.910]. The models address low resolution (VGA/WVGA) application areas, including services such as mobile TV, as well as high resolution (HD) application areas, including services such as IPTV.

This Recommendation is to be used with video encoded using ITU-T H.264 and media payload encapsulated in RTP/UDP/IP packets for low resolution video and encapsulated in MPEG-TS/RTP/UDP/IP for high resolution video.

The models in this Recommendation measure the visual effect of spatial and temporal degradations as a result of video coding, erroneous transmission, or video rescaling. The models may be used for applications such as to monitor the quality of deployed networks to ensure their operational readiness or to benchmark service quality. The models in this Recommendation can also be used for lab testing of video transmission systems.

The models identified in this Recommendation have limited precision. Therefore, directly comparing model results can be misleading. The accuracy of models has to be understood and taken into account (e.g., using [ITU-T J.149]).

The validation test material consisted of video encoded using different implementations of [ITU-T H.264]. It included media transmitted over wired and wireless networks, such as WIFI and 3G mobile networks. The transmission impairments included error conditions, such as dropped packets and packet delay, from simulations and from transmission over commercially operated networks.

The following source reference channel (SRC) conditions were included in the validation test:

• 1080i 60 Hz (29.97 fps);
• 1080p (25 fps);
• 1080i 50 Hz (25 fps);
• 1080p (29.97 fps); SRC duration: HD: 10 s,
• VGA/WVGA: 10 s or 15 s (rebuffering);
• VGA at 25 and 30 frames-per-second;
• WVGA at 25 and 30 frames-per-second.

¹ This Recommendation includes an electronic attachment containing test vectors, including video sequences, bitstream files and predicted objective model scores.