NVIDIA NVENC accelerated H.264/AVC encoding
Whenever asked about ?Have you heard of NVIDIA NVENC??, most people would say ?I have no idea what that is?. At the same time it is something that is essential for modern person. Most downloadable TV series and shows, Blu-ray videos, online streams (Including YouTube and iTunes) use H.264 video encoding technology that NVIDIA NVENC performs. For years H.264 was the most efficient compression method. With its low bitrate requirement as well as widespread availability, H.264 found its place in all video playback devices. For years this method of encoding was unmatched.
H.264 processes video frames by using so called macroblocks. Those are 16×16 pixel samples that allow further subdivision. What that means in simple words is that it allows lowering the bitrates in more efficient way than it used to be in older standards while retaining the same video quality.
NVIDIA NVENC acceleration for H.265/HEVC
H.264, while still being extremely popular and widely used, isn?t however the best encoding method currently in use. HEVC (H.265 or High Efficiency Video Coding) produces much higher standard than its predecessor with the same settings applied. In other words, if we want to have the same quality of video watched in H.264, we only need 50% of bitrates. Let?s say that we?ve recorded a short video with the use of H.264 encoding with 15000 bitrate, 60fps and ultra quality, giving us a file 500MB in size. While the video surely looks amazing in the end, it is possible to use HEVC/H.265 encoding and achieve exactly the same results at only 7500 bitrate and video size will be reduced to about 250MB.
But how exactly does it work?
Both H.264 and H.265 use motion compensation prediction, by searching for unnecessary areas within one or consecutive frames. Once such unnecessary areas are identified, the encoding process references another area in those frames. Simply put, when 2 areas on a frame are similar (for example, blue wall on around 70% of the video frame) then they are counted as one. I?ve mentioned that in case of H.264 those areas can be maximum 16×16 pixels in size. The big difference appears here, because HEVC allows to identify areas of up to 64×64 pixels in size. HEVC is also encoding much more efficiently due to its improved variable block-size segmentation. This means that the shape of the area isn?t limited to square blocks only. For those who seek more technical description, visit wikipedia entry that expands on the idea.
So the big question may arise at this point. Why do we still even mention H.264 encoding technology, since we have something that is literally twice as good. The answer is fortunately quite simple. H.264 encoding performed by NVIDIA NVENC is currently compatible with every single device as well as service that uses encoding technology. At the same time HEVC encoding technology, even though is more than 4 years old, is still incompatible with most devices and services. Some of the hardware support for HEVC includes:
1. Samsung Exynos 5 Octa 5430 SoCs and newer models.
- Apple A8 SoCs and newer models
- Nvidia GeForce GTX 960 or newer (Older models support HEVC only partially)
- Intel 6th gen ?Skylake? Core processors and newer models
- AMD 6th gen ?Carizzo? APUs and newer models
- Qualcomm Snapdragon 805/615/410/208 SoCs and newer models.
These are only a few among others, but all in all there aren?t many devices that support encoding in HEVC.
There is a group of people which may be concerned with that more than anyone else – ie. streamers. Not only do I mean live streaming of games but also those who watch VoD?s on a daily basis (especially Netflix users). Neither YouTube nor Twitch support HEVC encoding. Even if you record a video at home in HEVC, once the video is uploaded to YouTube, it is reconverted back to H.264. And while indeed you?ve saved space on your PC as well as bandwidth to stream your game as well as time to upload the video, the overall quality remains the same at best. If you record with the use of HEVC with 7500 bitrate, your video on Youtube would have quality the same as it would be when recorded with NVENC at 7500 bitrate.
Why HEVC is so limited when it comes to accessibility?
The answer to that question is relatively simple. It?s all about money. On one hand, producers of modern TV?s do not want to create new models supporting this ?new? technology since there are not enough users who can benefit from HEVC in the first place. On the other hand, sites such as Netflix or YouTube do not support HEVC encoding due to the fact that there are not enough devices who can actually see the difference in HEVC. It is indeed a paradox that prevents superior technology from going into market in a full swing.
What does it mean for users who record gameplay on everyday basis?
Users who use their PC on a daily basis and who want to record their PC activity quite often may still benefit from HEVC as I?ve mentioned before. No matter if you record a specific tutorial, or play a video game. In every aspect your video will weigh much less on your hard drive what allows you to store much more footage. The greatest problem is when you livestream your activity for others to see or just upload a video. This way using HEVC misses its point, because most services similar to YouTube do not support H.265 encoding.
Concluding, HEVC even though is much better choice for encoding, is still not supported by many devices and services. Perhaps it is still too early for this technology to become mainstream, or maybe people are just greedy enough and do not want to spend additional dollar to boost the accessibility of this technology. Because of that, H.264 remains the commonly used encoding method.
Author: Mirillis Team