![]() Finally the computational complexities of three tested codecs are compared. Furthermore, HEVC and AV1 are compared within a dynamic optimization framework (convex hull rate-distortion optimization) across resolutions with a wider bitrate, using both objective and subjective evaluations. The subjective quality of their reconstructed content is also evaluated through psychophysical experiments. The compression efficiency of the three codecs are evaluated using two commonly used objective quality metrics, PSNR and VMAF. Nine source sequences were carefully selected to offer both diversity and representativeness, and different resolution versions were encoded by all three codecs at pre-defined target bitrates. Streaming lossless media isn’t feasible for most Internet connections, which is why lossy codecs like H.264 and H.265 prevail online.In this paper, the performance of three state-of-the-art video codecs: High Efficiency Video Coding (HEVC) Test Model (HM), AOMedia Video 1 (AV1) and Versatile Video Coding Test Model (VTM), are evaluated using both objective and subjective quality assessments. It’s a trade-off between quality and playback experience, with lossy codecs offering much smoother playback that might include interpolation and other compression artifacts. During playback, lossless codecs completely reconstruct the compressed data while lossy codecs serve up only an approximation. But out of all of them, H.264 and H.265 get the most attention by far.Ĭodecs come in two classes: lossless and lossy. MPEG-2, JPEG2000, and VP9 are just a few you might hear about. There are lots of different video codecs out there. The codec comes into play at the start, determining how the raw footage and sound are compressed within the container, and decodes the file for playback as needed. The difference is this: A container holds the compressed video and audio and any other components of the file, such as any metadata or subtitles. For video files, that means formats like AVI, MOV, or MP4. The term itself is a combination of the words “coding” and “decoding.”Ĭodecs are often confused with containers. There are also audio codecs that do the same for audio. But what even is a “codec”?Ī video codec is a process for compressing and decompressing video data. It’s a term you’ll hear often in the streaming world and probably use a fair bit yourself. H.265: Average bandwidth required per resolution But the shift from macroblocks to CTUs is the most significant contributor to H.265’s greater efficiency. There are other technological enhancements at work, such as superior motion compensation and spatial prediction. H.265 uses a newer block structure called coding tree units (CTUs), which can process sizes of up to 64×64 pixels. H.264 uses what are called macroblocks, processing units that span 4×4 to 16×16 pixels. What accounts for this difference is how each video compression standard processes frames. This is a big advantage especially when it comes to storing and streaming 4K video and other high-resolution video content. The benefits of this are twofold: H.265 video files don’t take up as much storage space, and they require less bandwidth to stream. The H.265 codec compresses information more efficiently than H.264, resulting in files of comparable video quality that are about half the size.
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