This paper presents the results of an informal subjective quality comparison between the current state of the emerging
High Efficiency Video Coding (HEVC) draft standard and the well-established H.264 / MPEG-4 AVC High Profile (HP)
for low-delay applications. The tests consisted of two basic encoding comparisons. First, we compare the Main profile
low-delay configuration of the HEVC reference software (HM) against a similarly configured H.264 / MPEG-4 AVC HP
reference encoder (JM). Additionally, to complement these results, the widely-recognized production-quality H.264 /
MPEG-4 AVC encoder known as x264 is compared with a production-quality HEVC implementation from eBrisk Video.
The encoding configurations are designed to reflect relevant application scenarios and to enable a fair comparison to the maximum extent feasible. When viewing HM and JM encoded video side-by-side in which the JM was configured to use approximately twice the bit rate of the HM encoded video, viewers indicated that they preferred the HM encoded video in approximately 74% of trials. Similarly, when comparing the eBrisk HEVC and x264 H.264 / MPEG-4 AVC
production encoders in which x264 was configured to use approximately twice the bit rate of the eBrisk encoded video, viewers indicated they preferred the eBrisk HEVC encoded video in approximately 62% of trials. The selection of which encoding was displayed on which side for the side-by-side viewing was established in a randomized manner, and the subjective viewing experiments were administered in a double-blind fashion. The results reported in this paper generally confirm that the HEVC design (as represented by HM version 7.1 and separately by a production-quality HEVC implementation) exhibits a substantial improvement in compression capability beyond that of H.264 / MPEG-4 AVC (as represented by a similarly-configured JM version 18.3 and x264 version core 122 r2184, respectively) for low-delay video applications, with HEVC exhibiting roughly twice or more of the overall compression capability of H.264 / MPEG-4 AVC.