"One, what is H.265
H.265 is a new video coding standard established after ITU-TVCEG followed by ITU-TVCEG. The H.265 standard surrounds the existing video coding standard H.264, reserves the original technologies, and improves some related technologies.
New technology uses advanced technology to improve the relationship between code stream, coding quality, delay and algorithm complexity, reaching optimization settings. Specific research contents include: increasing compression efficiency, improving robustness and error recovery capabilities, reducing real-time delays, reducing channel acquisition time and random access delay, reducing complexity, etc. Since the algorithm optimization, the H265 can be achieved at a speed of less than 1 Mbps, and H265 can realize the transfer of 720P (resolution 1280 * 720) to transmit 720P (resolution 1280 * 720) to transmit the transmission speed of 1 to 2 mbps.
The H.265 is intended to transmit higher quality network videos under limited bandwidth, and only the original half band width can play the same quality video. This also means that our smartphones, tablets and other mobile devices will be able to play directly online 1080P full HD video. The H.265 standard also supports 4K (4096 × 2160) and 8K (8192 × 4320) ultra HD video. It can be said that the H.265 standard allows network video to keep up with "high resolution" footsteps.
Second, what is H.264
H.264, is also the tenth part of the MPEG-4, which is proposed by the ITU-T video coding expert group (VCEG) and the ISO / IEC Dynamic Image Expert Group (MPEG) combined with video group (JVT, Joint Video Team) Highly compressed digital video codec standard. This standard is generally referred to as H.264 / AVC (or AVC / H.264 or H.264 / MPEG-4AVC or MPEG-4 / H.264 AVC) to express its two developers.
The maximum advantage of H.264 is to have a high data compression ratio. Under the conditions of the same image quality, the compression ratio of H.264 is 2 times the MPEG-2, which is 1.5 to 2 times the MPEG-4. For example, if the size of the original file is 88GB, it is 3.5GB after compressing the MPEG-2 compression standard, and the compression ratio is 25: 1, and the compression ratio is compressed by the compression standard to 879MB, from 88GB to 879MB, The compression ratio of H.264 is an amazing 102: 1. The low bit rate has an important role in the high compression ratio of H.264, and the H.264 compression technology will greatly save users' download times compared to compression technology such as MPEG-2 and MPEG-4ASP. Data traffic charges. It is particularly worth mentioning that H.264 also has a high quality image while having a high compression ratio, as in this way, after the H.264 compressed video data, less bandwidth required in the network transmission process, It is also more economical.
For the H.264 encoding format, according to different resolutions, it is recommended that the corresponding code rate configuration relationship is shown in the following figure:
Widescreen:
Non-widescreen:
Third, H.265 is different from H.264
Before discussing H.265, we may wish to first understand H.264. H.264 is also known as MPEG-4AVC (Advanced Video Coding, Advanced Video Coding), is a video compression standard, and is also a recorded, compressed and release format that is widely used high-precision video. H.264 is famous for its codec standard for a Blu-ray disc, and all Blu-ray players must be able to decode H.264. More importantly, because Apple has finally abandoned Adobe's VP6 encoding, I chose H.264. This standard also walked thousands of households with billions of iPad and iPhone, became the current video coding field. Absolute overlord accounts for more than 80% of the share. H.264 is also widely used in network streaming media data, various high-definition television broadcasts, and satellite TV broadcasts. H.264 has some new features compared to previous coding standards, such as motion compensation, change block size motion compensation, intra predictive coding, etc., H.264 is more than other coding standards by using these new features. High video quality and lower code rates have been widely approved by people.
The H.265 / HEVC encoding architecture is similar to the architecture of H.264 / AVC, which mainly comprises: intra prediction, inter-intermediction, transform, quantization, Go to block filters, entropy codes and other modules. However, in the HEVC coding architecture, the whole is divided into three basic units, namely: Coding Unit, Cu, predictor (PU), and Transform Unit, TUs, respectively.
Fourth, H.265 Why is it better than H.264
More different tools are provided by H.264 / AVC, H.265 / HEVC to reduce the code rate, in the coding unit, the smallest 8x8 to the maximum 64x64. There are not many areas of information (color variations are not obvious, such as the red part of the vehicle body and the gray part of the ground) are large, and the coded is less code, and the details of the details (tires) are divided into macro The block has a small and more, the encoded codeword is more, which is equivalent to the encoding of the image, thereby reducing the overall code rate, and the encoding efficiency is correspondingly improved. At the same time, the intra prediction mode of H.265 supports 33 directions (H.264 only supports only 8), and provides better motion compensation processing and vector prediction methods.
Repeated quality comparison tests have shown that under the same image quality, the video code stream encoded by H.265 is reduced by approximately 39-44% compared to H.265 compared to H.264. This data will also have corresponding changes due to differences in quality control measurement. According to the data derived by subjective visual test, the quality of the H.265 encoded video can be approximately even better with the H.264 encoded video in the case of a rate of 51-74%, which is essentially more than expected. The signal to noise ratio (PSNR) is good. These subjective visual tests have covered many disciplines, including psychology and human eye visual characteristics, and video samples are very broad, although they can't be the final conclusion, but this is also very inspiring results.
The current HEVC standard has three modes: Main, Main10 and Main Still Picture. The main model supports 8Bit color depth (ie, 256 chromasings each having a total of 167 million colors). The MAIN10 mode supports 10 bit color depth, which will be used in UHDTVs (UHDTV). The top two will limit the color sampling format to 4: 2: 0. It is expected that the standard will be expanded in 2014, which will support 4: 2: 2 and 4: 4: 4 sampling format (ie, higher color reduction) and multi-view encoding (eg, 3D stereo video coding).
In fact, H.265 and H.264 standards have some overlap in various functions. For example, the HI10P part in the H.264 standard supports 10 bit color deep video. Another part of H.264 (Hi444PP) can also support 4: 4: 4 chrominance sampling and 14-bit deep. In this case, the difference between H.265 and H.264 reflects that the former can use fewer bandwidth to provide the same function, the price is the device computing power: H.265 encoded video requires more computing power To decode. There is already a chip that supports H.265 decoding - US Broadcom has released a Brahma BCM 7445 chip in the CES exhibition in early January, which is a quad-core processor using 28 nano-processes. It can simultaneously transcode four 1080p video data streams or resolutions of H.265 encoding ultra HD videos in 4096 × 2160.
The birth of the H.265 standard is to transmit higher quality network video under limited bandwidth. For most professionals, the H.265 coding standard is not unfamiliar, which is the video coding standard established after ITU-TVCEG followed by H.264. The H.265 standard is mainly surrounded by the existing video coding standard H.264. In addition to some other technologies, it has increased the relationship between improved code stream, coding quality, delay and algorithm complexity. Related technology. The main contents of H.265 include increasing compression efficiency, improving robustness and error recovery capabilities, reducing real-time delays, reducing channel acquisition time and random access delay, reducing complexity.
Further reading: Integrated wiring common nouns Daquan
5. How to calculate how video storage under H.264 and H.265 technology
1, H.264 technical hard disk capacity calculation
Speaking of calculation, what do we have to calculate? In addition to the number of cameras, there is an important value: code rate! Under normal circumstances, the size of the stream is, the greater, such as We often use the 130W camera, the code stream is 2MB / s, which is 2048kbps. Then I know the code stream, time, channel number, we can directly set the formula.
The formula is as follows: Code rate × 3600 × 24 ÷ 8 ÷ 1024 ÷ 1024 = 1d (one day)
Codeflow table
It should be measured for the code stream, so our capacity should also be converted in seconds, 3600, is 1 hour, 24 is 24 hours a day, 8, is byte, 1024 should be the code stream is The MB is unit, so that the conversion G is to be divided by 1024, replace it to T, then 1024. Fruit is 1 day. Party A needs how long it is stored, and then it is OK by the number of days.
The above is the calculation method of H.264, then let's take a look at the application of H.265 technology.
2, H.256 technology hard disk storage calculation
Example:
H.264 technology, 4 300W storage probably: 60g * 4 * 30 = 7.2T
H.265 Under Technology, 4 300W storage is probably: 30g * 4 * 30 = 3.6T
The following figure is more direct
This is still stored, let's take a look at the bandwidth. In the past, H.264 is required to watch the HD screen of 1 130W pixels remotely, it takes 6m uplink bandwidth, while H.265, 4M network can see a 300W HD picture. 2 200W screens.
Therefore, the cost of reduction is not just a hard disk storage, of course, there is a switch.
b, how to support H.265?
Is it that I use the old camera to receive a video recorder of H.265, can you store it? No, for the webcam and recorder, both parties support H.265 technology.
If there is one support, the other party does not support it? Rest assured, the same as other technical equipment, compatible, that is, other functions are normal in addition to storage reduction.
How to calculate C, H.265 Storage?
Ordinary camera is about 21g a day, is it directly divided by 2? actually not. A more concise method is coming!
200w≈20g
300W ≈30g
400W ≈40g
In fact, H.265 is compressed with a stream.
Transfer from: https://www.sohu.com/a/224199309_825275
The ultra HD trend of digital video is forward, and the frame rate is advanced from 30 fps to 60fps, 120fps or even 240fps. At the same time, the physical media Day is the Type of Xishan, and the content is transmitted through the terminal device in the world's various corners. Highly intensive data brings great challenges to bandwidth and storage. The current mainstream H.264 begins to apply, and the new generation of video coding standard H.265 seems to be a "savior" in the digital 4K era. H.265 is also known as HEVC (full name High Efficiency Video Coding, high efficiency video coding, this culture is called H.265), is a successor of ITU-T H.264 / MPEG-4 AVC standard. In 2004, ISO / IEC MOVING PICTURE EXPERTS Group (MPEG) and ITU-T Video Coding Experts Group (VCEG) are set as ISO / IEC 23008-2 MPEG-H Part 2 or as ITU-T H.265 is started. The first edition of HEVC / H.265 video compression standard was accepted as a formal standard for the International Telecommunication Union (ITU-T) on April 13, 2013. Be
Theoretically increased H.265 than H.264 efficiency by 30-50% (especially in higher resolution conditions), is it really just as simple?
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H.265 changes
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The H.265 reuses many concepts defined in H.264. Both are block-based video coding techniques, so they have the same root source, and similar encoding methods, including:
1. Segment the picture with a macroblock and finally subdivided by block.
2. Reduce spatial redundancy using intra compression technology.
3. Reduce time redundancy (motion estimation and compensation) using intra compression technology.
4. Use conversion and quantization to perform residual data compression.
5. Reduce the last redundancy in residual and motion vector transmission and signal transmission using entropy coding.
In fact, video codec is not fundamentally improved from MPEG-1, and H.265 is just a more powerful evolution and simplification of H.264 in some key performance.
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When you consider "It's just to transmit 4K content on ordinary Internet, or to achieve the best image quality", you must first clarify the two concepts of "more compression" and "better compression". If it is just more compression, 4K and ultra HD do not have to ensure better picture quality than today's 1080P or HD. Better compression means smarter compression, facing the same original material, better compression will reduce the amount of data in the case where the quality is not sacrificed. More compression is easyAnd better compression requires more thinking and better technology, processing images through more intelligent algorithms, maintaining lower bit rate while maintaining quality, which is what H.265 is required.
How to achieve better compression, for example, we usually find that in a lot of image materials, such as video conferencing or movies, most of the contents on each frame do not change too much, video conference In general, only the speaker's head is moving (even only with lips), and the background is generally not moving. In this case, our approach is not per pixel code for each frame, but the initial Frame encoding, and then only encodes a change in the change.
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H.265 is moving toward "better compression" from the following aspects.
Image partition
The H.265 divides the image into "Coding Tree Blocks, CTU", rather than 16 × 16 macroblocks like H.264. According to different coding settings, the size of the tree blocking block can be set to 64 × 64 or limited 32 × 32 or 16 × 16. Many studies have exhibited a larger tree blocking block to provide higher compression efficiency (also requires a higher coding speed). Each tree encoding block can be recursively divided, using a quadruple structure, divided into sub-regions of 32 × 32, 16 × 16, 8 × 8, and the following figure is a partition example of a 64 × 64 tree encoding block. Each image is further distinguished into a special tree block group, called a slice and a tiles. The encoding tree unit is the basic coding unit of H.264, as macroblocks with H.264. The encoding tree unit can be subjected to a downward coding unit (CODING Unit, Cu), a prediction unit (PU), and Transform Unit, TU).
Each encoded tree unit contains 1 brightness and 2 color encoding a tree, and a syntax element that records additional information. Generally speaking, most of the film is compressed in YUV 4: 2: 0, thus as an example of 16 x 16, which contains 1 16 x 16 brightness encoding tree block, and 2 8 x 8 chromaticity encoding tree block.
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The encoding unit is a basic prediction unit of H.265. Typically, the smaller coding unit is used in the detail region (e.g., boundary, etc.), while a larger coding unit is used in a predictable planar region.
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Conversion size
Each coding unit can be recursively divided into a conversion unit in a quadruple tree. The H.264 is mainly converted with 4 × 4 conversion, and occasionally vary from 8 × 8 conversion, H.265 has several conversion sizes: 32 × 32, 16 × 16, 8 × 8 and 4 × 4. From a mathematical perspective, a larger conversion unit can better encode static signals, while smaller conversion units can better encode smaller "pulse" signals.
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Predictive unit
Before converting and quantify, first is the prediction phase (including intra prediction and inter prediction).
A coding unit can be predicted using one of the following eight prediction modes.
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Even if a coding unit contains one, two or four prediction units, a special inter-frame or intra prediction technique can be used to predict it, and the internal encoded coding unit can only use a square division of 2n × 2n or N × N. . The encoded coding unit can be divided into a square and non-normally modified manner.
Inframe prediction: HEVC has 35 different intra prediction modes (including 9 AVCs already), including DC mode, Planar mode, and 33 directions. The intra prediction can follow the divided tree of the conversion unit, so the prediction mode can be applied to the converted unit of 4 × 4, 8 × 8, 16 × 16 and 32 × 32.
Inter Bloom Prediction: For motion vectors, H.265 has two reference tables: L0 and L1. Each has 16 reference items, but the maximum number of unique pictures is 8. H.265 Motion estimation is more complicated than H.264. It uses the list index, there are two main prediction modes: merge and advanced motion vector (Merge and Advanced MV.).
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In the encoding process, the prediction unit is a predicted basic unit, and the transform unit is a basic unit for transforming and quantization. The separation of these three units makes the transformation, prediction, and encoding various processing links,
Go to block
Different from H.264 in 4 × 4 blocks, it is different that HEVC can only implement a block on 8 × 8 grid. This allows for parallel processing (no filter overlap). First of all, the block is all vertical edges in the picture, followed by all horizontal edges. The same filter is used with H.264.
Sample adaptive offset
There is also a second optional filter after going to block, called sampling point adaptive offset. It is similar to the deblock filter, and the application is stored in the reference frame list in the prediction cycle. The target of this filter is to revise the error prediction, encoding drift, etc., and apply adaptive to offset.
Parallel processing
Since the decoding of HEVC is more complicated than AVC, some techniques have been allowed to implement parallel decoding. The most important thing is to collage and wavefront. The image is divided into a rectangular mesh of a tree coding unit. The current chip architecture has gradually developed from single nuclear performance, so in order to adapt to a very high degree of chip implementation, H.265 introduces a lot of parallel operations.
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All in all, HEVC pushes traditional block-based video coding mode to higher efficiency levels, summarizing it:
- Variable size conversion (from 4 × 4 to 32 × 32)
- Predictive area of the four-tree structure (from 64 × 64 to 4 × 4)
Motion Vector Prediction Based on Candidates List.
- A variety of intra prediction modes.
- More precise motion compensation filters.
- Optimized to block, sample point adaptive offset filter, etc.
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Key coding characteristics
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Significant improvement in H.265 is not only in the frame compression, not only in the field of inter-frame compression, but also manifested in intra compression. Since the variable size conversion, H.265 has great improvements in block compression, but it also brings some new challenges while increasing compression efficiency.
Video coding is a complex issue that is high for content. As is well known, there is a static background and highlighted low-dynamic scenes that can be more compressed than the picture of the black field. Therefore, for the modern codec like H.264, the first solve the most difficult scene / situation. For example, there is a key frame, high dynamic "crisp" image, slow dynamic, noise / texture, etc. in the dark area.
H.265 is more efficient in intra encoding, so the detail area can be encoded better, and the same is true in smooth areas and gradient regions. Compared to H.264, the motion estimation and compression of H.265 is more efficient, and can be operated at a lower bit rate before artifacts. The good news is that the fake shadow generated by H.265 is more "smooth", and the quality reduction is also very coordinated, even when the very radical resolution / bit rate is encoded, it feels well.
However, as two sides of the coin, when proof the slow dynamic and noise / texture of the dark area, the advantages of H.265 will become a weak. Dark area and noise / texture require more accurate high-frequency retention and smaller color order changes. This is often referred to as coding psychological optimization.
Since H.264 uses small conversions, the quantization error can be easily turned into features / details, although it is different from the original content, but feels "approximation". Error generation proximity to the native frequency range can be blocked by small boundary conversion, so it is also more controllable. The greater converted H.265 will be more complicated to use this way.
The storage of H.265 encoded video is still a problem, even if the Blu-ray CD association is seeking a solution that can store 4K video on a Blu-ray disc. Only at least 100GB capacity is reached to store the Blu-ray 4K movie encoded by H.264. On the other hand, even if H.265 encoding and chip components are ready, the storage and playback solutions that support 4K content are still lacking, and can be compatible with existing Blu-ray standards. This is also a major challenge in H.265 development.
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When you consider "It's just to transmit 4K content on ordinary Internet, or to achieve the best image quality", you must first clarify the two concepts of "more compression" and "better compression". If it is just more compression, 4K and ultra HD do not have to ensure better picture quality than today's 1080P or HD. Better compression means smarter compression, facing the same original material, better compression will reduce the amount of data in the case where the quality is not sacrificed. More compression is easy, and better compression requires more thinking and better techniques, handling images through more intelligent algorithms, maintaining lower bit rate while maintaining quality, this is H.265 What to do.
How to achieve better compression, for example, we usually find that in a lot of image materials, such as video conferencing or movies, most of the contents on each frame do not change too much, video conference In general, only the speaker's head is moving (even only with lips), and the background is generally not moving. In this case, our approach is not per pixel code for each frame, but the initial Frame encoding, and then only encodes a change in the change.
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While H.265, the successor VP9 of Google VP8 has also been launched, and the code efficiency is increased by 50% on the basis of VP8, support 8K content. VP9 is an open source and free specification, part of the webm architecture. Google has been integrated in the Chrome browser and YouTube.
Similar to H.265 on the surface, it can also capture 64 × 64 super blocks. But 265 is different, it is not necessarily square form, so it can sample 64 × 32 or 4 × 8 blocks to achieve greater benefits. But on the other hand, it has only 10 prediction modes to rebuild them.
Both simplified existing formats, although similar file size, there is a preliminary report that H.265 has higher image quality, while VP9 is more reliable for streaming media. The H.265's larger predictive model enables edge visualization, while VP9 implements a stricter coding rule, which seems to make the streaming media more coherent and reliable.
The comparison between H.265 and VP9 is similar to the comparison of HDMI and DisplayPort. The latter will strive for a seat in a copyrighted manner, but the former's ubiquitous application means it will have a wider industry support. This is also the reason for the previous H.264 easily defeated VP8.
At the same time, the third compression format is also among the planning, the XIPH.org Foundation has developed "daala", although it is still relatively far, but XIPH said it will be a new generation of a new generation of H.265 and VP9.
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High pixels result in a more complex codec to minimize bandwidth requirements. The minimum code stream that continuously connects to the PC or TV, the smoothing 4K signal is 20 Mbit / s, such as Netflix requires a user's Internet connection to provide at least 25 Mbit / s bandwidth. 20 to 25 Mbit / s represent a huge improvement of bandwidth, native, non-compressed 4K video needs to be good at 60Mbit / s bandwidth.
For most industrial applications, H.265 is one of the answers to the answer to this issue, but also pay a certain price: significantly increased algorithm complexity is said to be 10 times current 2K deployment of H.264 codec Calculation capabilities are supported, and the silicon required for this capability is also far from a simple commodity entry.
Many manufacturers want to solve cost and functional imbalances in the efforts of upstream chips and IC technology suppliers, so that H.265 quickly replaces H264. As far as it is, H.265 has a better development in the field of radio and television, but it will also become a mainstream norm in the professional application. Because of the fields of security monitoring are not only subject to the above challenges, but also the end user. For the general consumer of the project, Ping An City, Traffic Detection and Bank Monitoring this kind of professional users need more stable and reliable systems. Most of them have been using existing technologies, which requires a longer verification cycle for whether H.265 is still worried.
On the other hand, consumers such as small and medium-sized enterprises and families, shop users need low installation, so it is more inclined to adopt new technologies. Based on this, H.265 may first succeed in SME applications and is recognized in the consumer market. If H.265 is rapidly mature, its compression efficiency is 50% higher than H.264, which can save 20% investment to ensure higher performance and replacement of network and system construction costs.
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