HDTV. The study was done with three videos with resolutions of 3840×1744 at 24 fps, 3840×2048 at 30 fps, and 3840×2160 at 30 fps. The five second video sequences showed people on a street, traffic, and a scene from the open source computer animated movie Sintel. The video sequences were encoded at five different bitrates using the HM-6.1.1 HEVC encoder and the JM-18.3 H.264/MPEG-4 AVC encoder. The subjective bit rate reductions were determined based on subjective assessment using mean opinion score values. The study compared HEVC MP with H.264/MPEG-4 AVC HP and showed that, for HEVC MP, the average bitrate reduction based on PSNR was 44.4%, while the average bitrate reduction based on subjective video quality was 66.5%. In a HEVC performance comparison released in April 2013, the HEVC MP and Main 10 Profile (M10P) were compared with H.264/MPEG-4 AVC HP and High 10 Profile (H10P) using 3840×2160 video sequences. The video sequences were encoded using the HM-10.0 HEVC encoder and the JM-18.4 H.264/MPEG-4 AVC encoder. The average bit rate reduction based on PSNR was 45% for inter frame video. In a video encoder comparison released in December 2013, the HM-10.0 HEVC encoder was compared with the x264 encoder (version r2334) and the VP9 encoder (version v1.2.0-3088-ga81bd12). The comparison used the Bjøntegaard-Delta bit-rate (BD-BR) measurement method, in which negative values tell how much lower the bit rate is reduced, and positive values tell how much the bit rate is increased for the same PSNR. In the comparison, the HM-10.0 HEVC encoder had the highest coding efficiency and, on average, to get the same objective quality, the x264 encoder needed to increase the bit rate by 66.4%, while the VP9 encoder needed to increase the bit rate by 79.4%. In a subjective video performance comparison released in May 2014, the JCT-VC compared the HEVC Main profile to the H.264/MPEG-4 AVC High profile. The comparison used mean opinion score values and was conducted by the BBC and the University of the West of Scotland. The video sequences were encoded using the HM-12.1 HEVC encoder and the JM-18.5 H.264/MPEG-4 AVC encoder. The comparison used a range of resolutions and the average bit rate reduction for HEVC was 59%. The average bit rate reduction for HEVC was 52% for 480p, 56% for 720p, 62% for 1080p, and 64% for 4K UHD. In a subjective video codec comparison released in August 2014 by the EPFL,