Picture-Quality Optimization for the High Definition TV Broadcast Chain

The High Definition scene is constantly changing. The arrival of Full HD flat panel displays, the constant improvement of the AVC encoder, and the trend towards 1920x1080 progressive broadcasting have changed the balances of the High Definition broadcasting chain. It is, therefore, required to revisit the TV-formats debate. This research project was set up to consider: End-viewer perceived quality for critical content when broadcasting 720p/50, 1080i/50, and 1080p/50. End-viewer perceived quality for critical content encoded with MPEG 2, VC1 and H.264/AVC in various bitrates. Industry trend to migrate from MPEG 2 at 18 Mbps to AVC at 12 Mbps. New techniques for better usage of the available bitrate. Research during the project showed that: MPEG 2 and AVC have different types of artifacts but the overall perceived quality is similar for the same bitrate. The choice depends on the viewer. 1080i/50 quality is highly dependent on the set of(de-) interlacer. A possible solution for better bitrate usage could be frame sub-sampling prior the encoding and frame interpolation on the decoder. Tests showed that it can work only for content with smooth motion or temporally filtered. For a certain bitrate, there is an optimal tradeoff between the resolution format and the perceived quality. It is, though, highly content dependent and therefore not easily exploitable.The results of the perception test conducted showed that: 720p, 1080i, and 1080p have differences in quality, not statistically significant for MPEG 2 encodings. 1080p and 720p are preferred to1080i for AVC encodings. Viewers prefer MPEG 2 artifacts to AVC arti-facts. Viewers prefer MPEG 2 at 18 Mbps to AVC at 12 Mbps Subjects that need to be investigated: The role of Kell factor in the comparison between 1080p and 720p for-mats. The simulation of the broadcast chain with less critical content.