The impact of transmission errors on progressive 720 lines HDTV coded with H.264

TV sent over the networks based on the Internet Protocol i.e. IPTV is moving towards high definition (HDTV). There has been quite a lot of work on how the HDTV is affected by different codecs and bitrates, but the impact of transmission errors over IP-networks have been less studied. This study was focusing on H.264 encoded 1280x720 progressive HDTV and was comparing three different concealment methods for different packet loss rates. The first was included in a propriety decoder, the second was part of FFMPEG and the third was freezing of different length. The target is to simulate what typically IPTV settop-boxes will do when encountering packet loss. Another aim was to study whether the presentation upscaled on the full HDTV screen or presented pixel mapped in a smaller area in the center of the sceen would have an effect on the quality. The results show that there were differences between the two packet loss concealment methods in FFMPEG and in the propriety codec. Freezing seemed to have similar effect as been reported before. For low rates of transmission errors the coding impairments has impact on the quality, but for higher degree of transmission errors these does not affect the quality, since they become overshadowed by transmission error. An interesting effect was found in that the higher bitrate videos goes from having higher quality for lower degree of packet loss rates, to having lower quality than the lower bitrate video at higher packet loss rates. The different way of presenting the video i.e. upscaled or not-upscaled was significant on the 95% level, but just about. It was not significant when considering DMOS i.e. the mean of the difference between the scores for the reference and the scores for the distorted sequences.