Currently, many cameras adopt the h. 265 coding standard, and the number of h.264 cameras gradually decreases. Why is h. 265 popular?What is the difference between h. 264 and h. 265?
What is the h. 265?
H.265 is the new video coding standard developed by itu-tvceg after h. 264. The h. 265 standard is based around the existing video coding standard h. 264, retaining some of the original technologies while improving some related ones.The new technology uses advanced techniques to improve the relationship between codestream, coding quality, latency, and algorithmic complexity to achieve optimal settings.
Specific research contents include: improving compression efficiency, improving robustness and error recovery ability, reducing real-time delay, reducing channel acquisition time and random access delay, reducing complexity, etc.Due to the optimization of H264 algorithm, it can realize standard definition digital image transmission at a speed lower than 1Mbps.H265 can use 1~2Mbps transmission speed to transmit 720P (resolution 1280*720) ordinary hd audio and video transmission.
H.265 is designed to transmit higher-quality video networks with limited bandwidth, and to broadcast the same quality video with only half the original bandwidth.It also means that our smartphones, tablets and other mobile devices will be able to play 1080p full hd video directly online.The h. 265 standard also supports 4K(4096 2160) and 8K(8192 4320) uhd video.Arguably, the h. 265 standard keeps the video network up to speed with the ‘high-resolution’ display.
What is the h. 264?
H.264, also part 10 of mpeg-4, is a highly compressed digital Video codec standard proposed by the Joint Video group (JVT), which is composed of the itu-t Video coding expert group (VCEG) and ISO/IEC dynamic image expert group (MPEG).This standard is often referred to as the h.264 /AVC (or the AVC/ h.264 or the h.264 / mpeg-4avc or the mpeg-4 / h.264 AVC), and clearly identifies the developers of both.
The greatest advantage of h.264 is its high data compression ratio. At the same image quality, the compression ratio of h.264 is more than twice that of mpeg-2 and 1.5 ~ 2 times that of mpeg-4.
For example, if the original file size is 88GB, the mpeg-2 compression standard becomes 3.5gb with a compression ratio of 25:1, while the h. 264 compression standard becomes 879MB. From 88GB to 879MB, the h. 264 compression ratio reaches a staggering 102:1.
Low Bit Rate plays an important role in the high compression of h. 264. Compared with other compression technologies such as mpeg-2 and mpeg-4asp, h. 264 compression technology will greatly save users’ download time and data traffic charges.In particular, h.264 has a high compression ratio and a high quality and smooth image, which is why the video data compressed by h.264 requires less bandwidth and is more economical for network transmission.
What is the difference between H.265 and H.264?
Before discussing the advantages and benefits of h. 265, let’s take a look at h. 264.H.264, also known as mpeg-4avc (Advanced Video Coding, Video Coding), is a Video compression standard and a widely used high-precision Video recording, compression and release format.H.264 is known as a standard for encoding and decoding blu-ray discs, and all blu-ray players must be able to decode h.264.
What’s more, because apple had decided to abandon Adobe’s VP6 coding and chose h.264, this standard entered thousands of households along with hundreds of millions of ipads and iphones, and became the absolute hegemony of video coding field at present, accounting for more than 80%.
H.264 is also widely used in the field of network streaming media data, various high-definition television broadcasting and satellite television broadcasting.Compared with previous coding standards, h.264 has some new features, such as multi-reference frame motion compensation, variable block size motion compensation, intra-frame predictive coding, etc. By taking advantage of these new features, h.264 has higher video quality and lower bit rate than other coding standards, so it is recognized by people and widely used.
The coding architecture of h. 265/HEVC is similar to that of h. 264/AVC in general, and it mainly includes intra prediction, inter prediction, transform, quantization, deblocking filter, entropy coding and other modules.However, in the HEVC coding architecture, the whole is divided into three basic units: coding unit (CU), prediction unit (PU) and transform unit (TU).
Why H.265 better than H.264? Compared with h. 264/AVC, h. 265/HEVC provides more different tools to reduce the code rate. In terms of coding units, each macro block (MB) in h. 264 is a fixed size of 16×16 pixels, while the coding units of h. 265 can be selected from the smallest size of 8×8 to the largest size of 64×64.
The code rate comparison between h. 265 and h. 264 at various resolutions
Repeated quality comparison tests have shown that, at the same image quality, the video bitstream size encoded by h. 265 is approximately 39-44% smaller than that of h. 264.Due to the different measurement methods of quality control, this data will also have corresponding changes.According to the data obtained through subjective visual test, the quality of h. 265 encoding video can be similar to or even better than h. 264 encoding video under the condition of reducing the code rate by 51-74%, which is essentially better than the expected signal to noise ratio (PSNR).The criteria for these subjective visual tests cover a wide range of disciplines, including psychology and human visual characteristics. The video sample is very extensive, and although they are not the final conclusion, they are also very encouraging results.
The current HEVC standard has three modes: Main, Main10, and Main Still Picture.The Main mode supports 8bit color depth (256 shades of red, green and blue for a total of 16.7 million colors), and the Main10 mode supports 10bit color depth, which will be used on UHDTV.Both limit the chroma sampling format to 4:2:0.The standard is expected to be expanded in 2014 to support 4:2:2 and 4:4:4 sampling formats (i.e., higher color reduction) and multi-view coding (e.g., 3D video coding).
In fact, the h. 265 and h. 264 standards overlap somewhat in terms of functionality.For example, the Hi10P part of the h.264 standard supports video with a 10-bit color depth.On the other hand, the h.264 portion (Hi444PP) can also support 4:4:4 chromaticity sampling and 14 darker than the feature.In this case, the difference between h. 265 and h. 264 is that the former can provide the same functionality with less bandwidth at the expense of device computing power: h. 265 encoded video requires more computing power to decode.There are already chips available that support h. 265 decoding — Broadcom announced at the CES show in early January that the Brahma BCM 7445 chip, a quad-core processor with a 28-nanometer process, can simultaneously transcode four 1080P video data streams or ultra-hd video encoded in h. 265 with a resolution of 4096*2160.
The h. 265 standard was born to transmit higher-quality network video with limited bandwidth.For most professionals, h. 265 coding standard is no stranger, which is the video coding standard developed by itu-tvceg after h. 264.The h. 265 standard is mainly around the existing video coding standard h. 264. In addition to retaining some of the original technologies, it adds some related technologies that can improve the relationship among codestream, coding quality, delay and algorithm complexity.The main contents of h. 265 include improving compression efficiency, improving robustness and error recovery, reducing real-time delay, reducing channel acquisition time and random access delay, and reducing complexity.