What is HEVC
H.265 or High Efficiency Video Coding (HEVC) is the next generation of H.264 which is commonly used in blu-ray encodings. It’s goal is to improve compression – not just add more – up to 50% over it’s predecessor, while attaining the same level of picture quality. It can also support resolutions up to 8192×4320 (8K).
There are two key groups that are helping move this industry forward, The Motion Picture Experts Group, and the International Telecommunication Union’s Telecommunication Standardization Sector (ITU-T). Side note: Could you please find an easier name ? Someone here is being a troll.
Their goal is to reduce the average bit-rate by 50% for fixed video quality, and higher quality at the same bit-rate, while remaining interoperable and network friendly.
Since the majority of internet bandwidth is video (I’m looking at you netflix), one can imagine by reducing the bit-rate of video while keeping quality high could significantly reduce the strain on current networks.
HEVC Frame Types
Similar to H.264 and MPEG-2, there are three types of frames: I, P, and B. These frame types are the core to video compression, but in newer codecs such as H.265, the algorithms used are becoming more sophisticated.
I Frame (Intra-coded picture): Like a static image, these frames are often used as references for decoding other frames. They are usually the biggest, with the most data, but are used as references for other frames to be smaller.
P Frame (Predicted picture): This frame uses data from the previous frame that is unchanged, and only updates the areas that have changed. This frame can use image data and/or motion vector displacements to create the frame.
B Frame (Bi-predictive picture): A more advanced version of P, as it looks at the frame before and after to create a frame. These frames are the most efficient for final file size, but significantly slow the encoding process.
How does H.265 work and how is it different
HEVC breaks down each frame into coding units (CU) which are small blocks ranging from 4×4 pixels, all the way up to 64×64 pixels. The old maximum size was 16×16. These blocks are then used to compare which areas of the frame to change, and which areas can be referenced from I-Frames.
There is also an increased number of modes for intra prediction, from 9 in H.264 to 35 in H.265. While that will be much more processor intensive, the larger blocks will be more efficient.
Image credit: elementaltechnologies.com
All these improvements sound great, but it needs a great deal of computational power, in some cases up to ten times. This is one of the reasons we have introduced multi-core encoders into our infrastructure. They can handle these calculations, and increased resolutions.
Each encoder can vary depending on it’s implementation and use of tools available. This includes but not limited to:
- Intra prediction
- Motion compensation
- Motion vector prediction
- Parallel processing
Heads up vs. VP9
There have been preliminary tests executed by the Fraunhofer Heinrich-Hertz-Institute on performance comparisons of H.264/MPEG-AVC and H.265/MPEG-HEVC and VP9.
In similar encoding configurations, H.265 saw bit-rate savings up to 43% over VP9 and 39% over H.264.
Encoding times were a totally different story, where VP9 outperformed H.265 by 7.3% and H.264 by 130%.
We’ve done our own tests, and in the example shown below, we’ve been able to get H.265 almost 50% smaller than H.264 with the same quality. Since there is no browser support for H.265 yet, you can download a chrome plugin, or play it with VLC player.
You can view the H.264 video below, which is 1.7MB, and download the H.265 video, which is 964KB.
Where the chips fall
Our initial tests show that VP9 and H.265 have similar file sizes, VP9 in conjunction with WebM seem to be more reliable for streaming. However, H.265 seems to have better image quality.
While this isn’t turning into a Blu-ray vs HD-DVD competition, VP9 does have a leg up being royalty free. Most companies have announced support for both formats, but YouTube has yet to support H.265, and is encoding most high res videos with VP9.
H.265 and Panda
The complexity and increased processing power needed for HEVC are well matched to infrastructure and software that Panda provides. We’ve recently added multi-core encoders just for this reason.
A few customers have had early H.265 access and we’re now opening up broader access. If your business is interested in being on the leading edge, email us to be a part of the private beta at firstname.lastname@example.org