H.264 compared to H.265
One of the main decisions in the use and design of video surveillance systems is the choice of codec. The correct choice and setting of the codec allows you to achieve the optimal balance between the quality of the resulting image and the efficiency of video transmission over the network.
The most common video surveillance codec is H.264. And although it is demanding in the computational part of CCTV, it allows you to compress video of a high enough quality for transmission over a local network or the Internet. But progress does not stop, and in 2012 the first chip capable of encoding a video signal in H.265 format was presented at the Mobile World Congress. This codec, according to the creators, is capable of halving the size of the resulting file compared to a file compressed with the H.264 codec. Such statements could not fail to arouse interest among manufacturers of video surveillance systems. This is understandable – the end result of using a more efficient codec should be direct savings. The widespread use of this codec in the market has not yet been observed, but the first cameras compatible with H.265 have already started to appear in Russia.
Assistive technologies such as Zipstream (created by Axis Communications) and H.264 + (Hikvision) are also capable of reducing network bandwidth and video storage requirements. There are many articles on the net that describe tests, comparisons of the quality of codecs with each other, manufacturers give many arguments in favor of their solutions. We decided to see in practice if all these technologies really work, if they can be effective competitors for the new H.265 codec.
H.265 codec
First, a little theory.
H.265, or HEVC (High Efficiency Video Coding in English), is a video compression format that uses more efficient algorithms compared to H.264 / MPEG-4 AVC. ITU-T Recommendation H.265 and ISO / IEC 23008-2 MPEG-H Part 2 have been jointly developed by the ITU-T Video Coding Expert Group (VCEG) and the MPEG Moving Picture Expert Group . The standard recommendation was developed in response to the increasing demand for higher compression rates for moving images for a wide variety of applications, such as webcasting, data transmission, video conferencing, digital storage, and television broadcasting.
To be honest, we walked in circles around the H.265 codec for a long time, not knowing which side to approach. There were many difficulties. The main one is that the cameras that support it can be counted on one hand. We took BEWARD B2250 and ActiveCam. Also, it turned out to be not so easy to play the recorded video stream compressed with the new codec, as manufacturers use modified codecs and the standard playback tools gave them up. The only player that did not refuse to play the received files is VLC Player. We started recording video under different conditions, changed the bitrate, plunged the scene into darkness, but the size of the video stream remained the same for H.264 and H.265. As well as the quality of the image, which could not be discerned with the naked eye.
Until the lowest quality of the resulting image from the cameras was established, the bit rate was 200 kbps, it was then that the fundamental difference between the two codecs became visible. The new codec works differently from the old one. H.265 is capable of encoding 64×64 pixel blocks, which improves encoding efficiency and reduces decoding time. In practice, a video stream encoded with the H.265 codec, at the same bit rate, provides more details than H.264. With the maximum setting (bit rate 8000 kbps and above), this is impossible to notice, but at the minimum (200 kbps), the difference is obvious.
Where are the savings? And you can save traffic and file space by reducing the bit rate of the H.265 codec and obtaining an image comparable to that of the compressed H.264 codec. Will the file size in H.265 be 50% smaller than that of files compressed with the H.264 codec? That is unlikely.
Most likely, the H.265 codec works well when using video surveillance features such as license plate recognition, as at the maximum setting the image is more detailed. However, it is not possible to test this theory in practice; There are still no similar solutions on the market that work with a video stream using a compressed H.265 codec. And until the new codec began to massively take over the market, vendors are actively introducing new technologies that lower the video bit rate without a significant difference in image quality. They all work well with the standard H.264 codec.
