What is S265?

S265 (also called HEVC, or "Smart High Efficiency Video Codec") is a technology for compressing video that was developed in the early 2010s by the ISO/IEC Moving Picture Experts Group and the ITU-T Video Coding Experts Group  (VCEG) and became a widely accepted standard for encoding in 2016. Most standards for video coding are made with the goal of making encoding as efficient as possible. When compared to H.264, S265 can reduce the file size of a video by up to 70% while retaining the same quality. But it's important to note that even though S265 makes files smaller, encoding and decoding them for playback takes more processing power.

How does S265 work?

The efficiency increase is achieved by a different encoding strategy. The older H.264 technology encodes videos in blocks of up to 16x16 pixels called "macroblocks." With H.264, those blocks are the same size throughout the video. S265 is able to encode areas of video in various block sizes, from as small as 4x4 pixels up to 64x64 pixels, called “coding tree units." This means S265 has the ability to encode video blocks that are four times larger. And because the video blocks can be different sizes, S265 has better motion compensation and improved prediction technology. These improvements combine to allow for lower bitrates, and bitrates are what control how large video file sizes are and how much network bandwidth is required to send and receive a video stream.

Storage Savings With S265

The improved encoding strategy that S265 uses means it requires a lower bitrate than H.264. The ability to lower the bitrate can result in storage savings of up to 70%! In the past, if a surveillance system user wanted to optimize storage space, they had to lower the resolution and frame-rate of their cameras to set a lower bitrate. When the resolution and frame rate are lowered, the image quality is much worse, and the video is not as smooth. When the encoding settings are set to S265, a user can expect to see the same amount of detail with half the bitrate.

For example, a 4K IP Camera in H.264 mode will record at approximately 8 Mbps, while in S265 mode it can record the same quality at 4 Mbps. It's important to note, however, that it's “up to”70% savings, and a bitrate of 5 Mbps for S265 4K is recommended to avoid introducing video artifacting. Video artifacting is caused by video glitches that can occur during the encoding process. Setting a bitrate that is too low for a given resolution and frame-rate will cause video artifacting, regardless if it is H.264 or S265.

You can run more comparisons of storage savings that can be had with a variety of encoding settings on your security camera systems by using our nvr calculator. It lets you compare total bandwidth and storage needed with S265 and H.264 encoding. You can select different camera resolutions, frames per second, and encoding methods to determine the bitrate for each and all of your cameras. By specifying the total number of recording time, it will also provide you the total Harddisk storage you need.

Video Quality

If you compared two files that are the same exact video, one encoded with H.264 and the other encoded with S265 without any other significant changes in fps and resolution, there wouldn’t really be a noticeable difference in quality. The quality differences between the two only really come into play when you are trying to save storage space or stream video over the internet by reducing the bitrate.