Website video is not clear? On the bit cost that cannot be ignored

Today, LCD technology is highly mature, and TV and display products carrying technology are also rising, leaving computer monitors aside, just talking about TV products, from 2014 to the present, as people's aesthetic fatigue on computers, mobile phones and other products, people The focus of the entertainment life has once again shifted to the living room, and TV products have experienced explosive growth in the past two years. According to our long-term observation of products, the active manufacturers in the market now have the same development trend of TV products. The interpretation is "bigger and clearer".

Website video is not clear? On the bit cost that cannot be ignored

In the living room environment where 4K TV is popular, our cable TV signal still stays at 480P resolution, which causes a waste of our TV hardware performance. Therefore, the Internet TV industry, which has Internet resources, came into being. As Internet resources supported by program resources, we can access more and clearer and more comprehensive film and television resources, but even the resources on the Internet have few resources with 4K programs, why? What exactly limits the quality of program resources on video sites?

Website video is not clear? On the bit cost that cannot be ignored

Youku video resources are up to 1080P resolution that members can only enjoy

Website video is not clear? On the bit cost that cannot be ignored

At present, the hot-spotting ghost blower network drama is a solo broadcast of Tencent video. Only members can enjoy 1080P resolution.

For the computer platform, with the current network environment in China, the mainstream video website resource resolution is generally around 256P-720P, which is still far from meeting the hardware effect of the mainstream display 1080P resolution, let alone the current living room environment. The raging 4K TV is actually causing this situation, and the video website is unwilling to see and is helpless, which involves a very large bit cost problem.

To understand the principle of video transmission on a video website, it is necessary to involve a name "bit rate" which is a more important part of the bit cost, and then give you a brief explanation.

Important little knowledge

The bit rate is also called the bit rate, and it indicates how many bits per second the video and audio data after compression encoding needs to be expressed, that is, the amount of data after the image displayed per second is compressed, the unit generally used is "KB" or thousands Bits per second.

Website video is not clear? On the bit cost that cannot be ignored

Video file definition and occupied space table (approximate)

Generally speaking, the larger the bit rate, the closer the processed file is to the original file, but the file size is proportional to the bit rate, so almost all encoding formats attach importance to how to achieve the least distortion with the lowest bit rate. The fixed bit rate and dynamic bit rate derived from this core are all articles in this regard:

Fixed bit rate: Refers to the file rate from beginning to end, which is a compression method based on the premise of fixed file size.

Dynamic bit rate: Refers to the fact that there is no fixed bit rate. When compressing, the video bit rate is used to immediately determine what bit rate to use. This is a compression method that takes into account the file size on the premise of quality. Many people may find that when watching a program on a video website, many programs stop after loading a segment of the progress bar. If they jump to the progress point of the progress point, they will reload. This segmented video connection mode , Also to save bandwidth.

Average bit rate: Usually refers to the average bit rate of digital music or video. For example, if the average bit rate of an MP3 file is 128kbps, that is, on average, 128,000 bits per second are transmitted / decoded. The bit rate is not the only standard for measuring audio / video quality. For example, some other formats, such as wma and ogg, can provide better sound quality at the same average bit rate as mp3 files.

Website video is not clear? On the bit cost that cannot be ignored

Video quality comparison (It can be seen that the quality of online video is much worse than that of local video, which is also a virtual standard for saving bandwidth)

If you process mp3 with an average value, you will see that the bit rate you specified (for example, 222KbPS) is the first choice for decompressing the current player, and the constant bit rate is just compressing the file with a fixed compression ratio. So what is the relationship between bit rate and bandwidth? How is the cost of bit and bandwidth calculated?

How to convert bandwidth to bit rate conversion bit rate

WEB-side video servers are divided into three types of technologies. The service-to-profit network video service technology from traditional AVI, RM, WMV, MPEG and other early streaming media videos has taken Adobe ’s Flash media service transmission for about 5 years. From FMS video The server-to-Flash technology makes it possible to realize P2P transmission between web pages, and it has been almost 5 years. The emergence of FMS has made large-scale video services a reality, but its high server bandwidth load cost has always been criticized within the industry. This situation did not change until after the emergence of P2P technology.

Website video is not clear? On the bit cost that cannot be ignored

Three bit server technologies

The method of bit conversion into KB generally calculates related data, and the relationship between the data represented by them is consistent. First of all, we must first clarify the following issues:

1. Usually, an online audience needs about 30k ~ 40k bandwidth to watch SD video smoothly.

2. The conversion method of bandwidth is that 128K traffic requires 1M network bandwidth. Generally, the download speed corresponding to the bandwidth of our home network is generally 2M bandwidth about 256KB / sec download speed, 4M about 512KB / sec, 8M-10M about 1024KB / sec.

Website video is not clear? On the bit cost that cannot be ignored

3. Similarly, the bandwidth required by the server is calculated based on the highest concurrent traffic that can be carried. Concurrent traffic refers to the traffic value of accessing resources at the same time. If FMS technology is used, to meet the demands of concurrent traffic, the traffic needs to be accumulated. For example, 100 people accessing video resources at the same time can calculate: 100 people multiplied by 30k is about 3000k; 3000k divided by 128k / M is about 23.4M. If the maximum number of concurrent video viewers on the site reaches 100, you need at least 20M of bandwidth If the maximum number of concurrent video viewers on a website reaches 1,000, you will need at least 200M of bandwidth. The data volume and page views of websites such as Tencent and Youku can be determined by not only a few million.

At present, the 100M bandwidth cost of the conventional configuration of domestic regular server providers is about 100,000 yuan / year. From this, it can be calculated that if the maximum concurrent volume of the website is expected to reach 1,000 people, the server bandwidth cost needs to be at least 200,000 / year or more, and if it reaches 5,000 people, at least 1 million / year or more. The above calculations are rough theoretical values ​​and are full load calculations. In actual operation, the server will not only consider the full load and the theoretical situation. Most of them use multiples of server bandwidth resources to ensure operational safety on this basis. The cost of running the website is pushing to a very horrible number.

As the number of people changes, only a small amount of user information interaction increases. Therefore, the greater the number of users in the FMS mode, the greater the pressure, and the greater the number of users in the P2P mode, the better. In the face of increased users, two different situations are presented. At present, with the rapid development of the mobile market and the gradual relaxation of domestic bandwidth traffic, the demand for video programming users has shown a clear high-intensity demand. High-volume diversified video services are gradually thawed, and the collapse of the high funding threshold is showing the tip of the iceberg of this trend.

Coding is also important or the best way to solve problems

The so-called encoding is to compile the captured video source file into another format to reduce the "weight" of the video file, so that the playback of web video resources is to reduce the data throughput, more efficient and smooth playback of video, video streaming The most important codec standards in transmission are ITU's H.261, H.263, H.264, and now the H.265 encoding format. In short, the excellent encoding format optimizes the processing steps of the video. Let's take a look at a set of comparison charts compiled by H.264 and H.265, so the performance is more intuitive.

Website video is not clear? On the bit cost that cannot be ignored

Comparison of H.265 encoding and H.264 encoding

Through the above picture, we can simply understand the two encoding formats as the process of drawing by two painters. We see that the H.264 format is to compile the video screen into small areas for compilation. The rendering process is more complicated , So the file size is large, and H.265 calculates the similar color and background blur, and needs to carefully encode the places that need to be highlighted, so that selective encoding can reduce the size of the video file by about 50%. This is a Very efficient upgrades, and also provides optimization from the source of the video to the bit rate of stored files and website playback.

H.265 is designed to transmit higher-quality network video under limited bandwidth. Only half of the original bandwidth can play the same quality video. This 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 and 8K UHD video. It can be said that the H.265 standard allows network video to keep up with the "high resolution" of the display.

Website video is not clear? On the bit cost that cannot be ignored

H.265 encoding format

Although there are still fewer video resources with more than 1080P resolution, many equipment manufacturers have now begun to popularize H.265 encoding technology. Mainstream TVs and HD set-top boxes are equipped with the latest H.265 video decoding functions. In a sense, this is also the first move of the soldiers, horses, and grass.

The situation is still awkward and urgently needs revolutionary technology

For many video companies, the bit cost, or even the amount of income, has to be paid for income. If you look at it from the perspective of development, the bit cost may be reduced to a certain extent, but it is certain that neither the existing standards such as ADSL, 3G, WiFI, etc., nor E1 and LTE in the future can reduce the bit cost to video. The expectations of the websites. Based on the understanding of telecommunication service facilities and the evolutionary situation, within the next five years, it is difficult for China's video service bit costs to be reduced to less than half of revenue, which also poses a great challenge to the increase of scaled marginal revenue.

Website video is not clear? On the bit cost that cannot be ignored

To keep the website running, you need to rent a server

Internet video service providers want to promote their own industry development. At the same time, the cost problem involved is not only the cost of program resources. At the same time, the pressure on data flow and storage also makes many video service providers overwhelmed. In terms of rigid bit cost, the cost of the search function is the lowest. It has only a simple input box, and the input and output are mainly text. The amount of information transmitted on the network is very small, and the information obtained from each user The biggest gain. Video services have the highest bit cost. The main transmission on the network is streaming media, which takes up a lot of bandwidth, takes a long time, and has a large amount of data.

For users, the TV is a tilt-back experience, the PC is a tilt-forward experience, and the mobile phone is a thumb experience. These three things are related, but they are not the same. The cost of time that users are willing to spend on these three things is different. To what extent can the experience of Internet video form disruptive changes? For video sites, following the traditional TV approach to higher definition and more interactive direction will only continue to increase the cost of bit. Larger resource levels require more bandwidth support, and data storage is also a part of the cost. This makes it difficult to get rid of the awkward situation of relying on huge amounts of resources for profit and spending huge bit costs. Want to achieve high-quality clarity There is still a long way to go for the popularization of video resources, and the true meaning of 4K Internet video signals is very difficult to achieve from the current results.

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