HEVC not just better on paper than H.264, visual tests involving 30 people proves that HEVC is superior, sometimes vastly superior, for ultra high definition content
With the Moving Picture Experts Group (MPEG) formally approving the successor to H.264 (AVC), unimaginatively dubbed as H.265, but better sounding as HEVC (High Efficiency Video Coding), a new study went out to find out if HEVC's increased efficiency could be easily seen by the naked eye. And the results didn't disappoint.
The research project at Ecole Polytechnique Federale de Lausanne in Lausanne, Switzerland, had 30 people to visually examine three complex video segements, encoded at various bitrates using both H.264 and HEVC, and asked them to rate the video out of a maximum score of 100, and in almost all cases, HEVC came out ahead.
The three video segments, all in near 4K resolution, were a computer animated one, one involving cars moving in traffic and another involving an overhead view of large group of people crossing a busy intersection. The former two, in video compression terms, were not "difficult", as the car traffic one has relatively fewer differences between subsequent frames (a static camera view in which the majority of the scene remained static), and the animation was very low in noise.
But for the more "difficult" pedestrian footage, in which most of the scene composed of people moving about, HEVC's credentials shone. For this footage, which was recorded 3840x2160 resolution, 4 out of the 5 test cases at different bitrates were won by HEVC. At a low 5 Mbps, too low for near 4K material, HECV still managed a score of nearly 70, compared to H.264's low 20's. It was only when the video bitrate was increased to 20 Mbps, that the differences between HEVC and H.264 narrowed, although HEVC was still ahead by a small margin.
The car traffic footage yielded a much smaller difference, with only one out of the 4 test cases proving HEVC was significantly superior. But HEVC again won easily with the animated footage, and amazingly managed to produce a score of 70 even at a bitrate as low as 0.75 Mbps.
The conclusion seems to be clear - HEVC is not just more efficient than H.264 on paper, it is also better from a visual perception point of view, especially in ultra high definition environments. The study concludes that HEVC would be the perfect video format to be used in future 4K and 8K UHDTV broadcasts.
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