HEVC Codec H.264 vs H.265: What Is The Difference?

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HEVC Codec, What is it ?

HEVC (High Efficiency Video Coding) , also known as H.265 and MPEG-H Part 2, is a video compression standard, one of several potential successors to the widely used AVC (H.264 or MPEG-4 Part 10). (source)

In comparison to AVC, HEVC offers about double the data compression ratio at the same level of video quality, or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD.

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Since a picture is worth a thousand words, the above photo is an example of the pixel pattern used in HEVC H.265 compared to H.264. In most ways, HEVC is an extension of the concepts in H.264/MPEG-4 AVC. Both work by comparing different parts of a frame of video to find areas that are redundant, both within a single frame as well as subsequent frames. These redundant areas are then replaced with a short description instead of the original pixels.

The primary changes for HEVC include the expansion of the pattern comparison and difference-coding areas from 16×16 pixel to sizes up to 64×64. Improved variable-block-size segmentation, improved “intra” prediction within the same picture, improved motion vector prediction and motion region merging. In Addition, the improved motion compensation filtering includes an additional filtering step called sample-adaptive offset filtering.

Effective use of these improvements requires much more signal processing capability for compressing the video, but has less impact on the amount of computation needed for decompression.

HEVC vs H.264 Comparison

First of all, both codecs work by comparing different parts of a video frame in order to find the ones that are redundant within the subsequent frames. These areas are replaced with a short information, describing the original pixels. Furthermore, what differs HEVC/H.265 from H.264 is the ability to expand the size of these areas into bigger or smaller blocks, called coding tree units (CTU) in the HEVC/H.265. Therefore the pattern CTU sizes can be from 4×4 to 64×64, whilst H.264 only allows a maximum block-size of 16×16 (CTU is particular feature of HEVC). (source)

HEVC replaces 16×16 pixel macroblocks, which were used with previous standards, with coding tree units (CTUs) which can use larger block structures of up to 64×64 samples and can better sub-partition the picture into variable sized structures. HEVC initially divides the picture into CTUs which can be 64×64, 32×32, or 16×16 with a larger pixel block size usually increasing the coding efficiency.

Where and How does HEVC affect Me?

H.265 is still less common than H.264, but it’s rapidly gaining market share. Apple’s new iPhone and iPad operating system, iOS 11, will store all video files in H.265. The newest generation of MacBook Pros include the Kaby Lake-powered hardware support for decoding the codec. The video format will also be used in Apple’s tvOS and Safari web browser for streaming video.

Last year, Microsoft released a free extension for Windows 10 that adds support for H.265 video decoding. Netflix’s 4K content is streamed with the H.265 codec on supported hardware. YouTube, on the other hand, does not use H.265, instead opting for their competing VP9 compression scheme.

But with H.265’s greater efficiency, we’re likely to see that codec dominate the marketplace in the years to come.

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Another easy way to find what codec is being used when streaming a media file in Kodi can be achieved by simply selecting the letter O on a keyboard. In the example above:

  1. This example is from a Krypton 17.6, using the Aeon MQ7 Skin. Not all skins will provide the same Codec information as show here, so keep that in mind.

  2. A – Shows the Codec, HD Resolution, Ratio, Audio version and the Audio ratio (5-1)

  3. B – Is what you will see after selecting the Letter O. This will offer far more detail (for you techno-nuts) Including the CPU Load found on the last row.

HEVC and H.264 in 1080p

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The above example is 1080p, ACC Audio and 2 channels as shown in B. While in A, found after using the O key, you will get a more detailed list of info.

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When compared to 1080p HEVC/H.265 you can now see just how much more information can be “packed” into a H.265 as opposed to H.264. Especially relevant is the Audio Stream, both are ACC but this example has 7.1. If you enjoy the Audio Quality as much as the Video Quality, you may soon find yourself looking for HEVC Streams more often.

HEVC in 4K Resolution

H.264

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H.265

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The example above is the same Movie File, with the screenshot taken at almost the exact same time for comparison. Missed it by 3 seconds!  I know it’s hard to see from the these photos but there is definitely a difference when viewing on your TV Screen. HEVC is by far a more clearer picture, yet both are the same resolution and the Audio options are equal as well.

In Conclusion

In the very near future, HEVC will revolutionize how video data is displayed, either online, on television and even in the surveillance industry. With this new format, image resolutions around 8192×4320 become possible to display and stream.

In a recent study where HEVC/H.265 presented a bit reduction of 52% at 480p and 64% at 4K UHD when compared to H.264. Besides this outstanding bit reduction, when compared to H.264, HEVC/H.265 delivers a significantly better visual quality, when compressed to the same file size or bitrate.

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