Four Misunderstandings in Building Online Video Broadcasting System

Online video live broadcast is a typical representative of streaming media applications, which can be widely used in network TV, video conferencing, distance education, medical consultation and other fields. Because many friends do not understand streaming media technology, there are many in the construction of video live broadcast systems. Misunderstanding, we have summarized it, roughly divided into the following four aspects.

Misunderstanding 1. Choose the server as the collection and encoding workstation.
Many friends think that the server is stable and has high performance. It is often used as a hardware device for collecting and encoding. In fact, because the main performance of the server is reflected in network throughput, disk IO, and logical operations, it is used in the multimedia processing part. The graphics card configuration is relatively low, and there are few suitable acquisition cards, so the server is not suitable for use as a live collection encoder.
It is generally recommended to use a PC with high graphics and image computing performance, CPU3.0 GHz, high-performance graphics card with independent video memory, 1G memory, and a high-end PC as a collection and encoding workstation. For the use of integrated video live software (collection , Coding, live broadcast release integration, a typical representative is LiveONE software produced by Century Sunflower Company) When building a video live broadcast system, we should first consider the acquisition and coding aspects, so it is recommended to use PC-based workstations as hardware options .

Misunderstanding 2. Choosing a streaming media server At present, many hardware server manufacturers have introduced "streaming media server" hardware equipment, paste the concept of streaming media to the server, and promote their own hardware products, which indeed brings many friends to choose. Misunderstanding; we know that streaming media is just a technology, typical applications include VOD on demand, live video, video broadcasting, etc., and the current streaming media technology involves many aspects, encoders, network transmission protocols, customers Receiving end; encoders include WMV series, DIVX series, XVID series, MPEG4 series, H.264 series, RM series, VP series, etc. The receiving end has Windows Media Player, RealONE, QuickTime, and various proprietary players, The network protocols include RTSP, MMS, Http, KMS, etc., and no unified standard has been formed yet. So there is no such thing as a streaming server.
Because the efficient operation of core video pumps such as streaming media distribution and VOD on-demand depends only on factors such as disk IO and network throughput, and does not require unique hardware equipment, we should pay special attention when selecting hardware equipment for the server. The streaming media concept advertised by some manufacturers has been "flickered", but it is necessary to choose the hardware server that suits you according to your actual situation.

Misunderstanding 3. Unrealistic and blind pursuit
1. Blindly pursue high-quality live broadcast effects;
2. Blindly pursue the big concurrency of the server;
3. Blindly pursue new technologies and standards.

High-quality live broadcast effects must meet the following conditions: good signal quality, good network conditions, and good configuration of the receiving end. For example: To meet the quality of the DVD effect, the following conditions must be met: the original signal quality is the DVD effect, at least 1M of bandwidth can be provided between the client and the server, and the receiving PC should be configured with at least P4 1.6GHZ / independent 32M video card.
The number of concurrent users supported depends on whether it can provide the corresponding network bandwidth. In the case of live broadcast in unicast mode, if the audio and video stream is M, to meet the simultaneous reception of N individuals, the live broadcast server needs M × N upstream bandwidth.
The development of new technologies is quite fast. New encoders and new network transmission methods are emerging one after another. When we do live video, the choice of encoder should not only consider its effect, but also should be from performance, compatibility, versatility, Reusability and other aspects are considered; the choice of network transmission mode also depends on the requirements for live broadcast. In short, we must choose according to our actual situation and requirements.
For example: H.264 has been sought after by many friends because of its good effect. From a technical point of view, H.264's effect is good, but if it is used in the live broadcast system without thinking, it will also cause many problems. Since there is currently no real H.264 solution for hardware encoding on the market, soft encoding is still required for H.264 to be fully effective. A machine can only be used for H.264 encoding with the current mainstream configuration. Encoding all the way signals, for friends who want to do network TV, the investment is quite large. In addition, if H.264 is used for encoding, the recorded file format does not have a unified standard, and it is difficult to perform secondary editing and multiplexing. Too.
Another example: the P2P method has developed rapidly and is gradually being used in live webcasts. However, due to the large occupation of the network by P2P, many units are not allowed to spread this way. With the P2P method, the network delay will reach 1 minute. Therefore, the P2P method is not suitable for the application of meeting live broadcast and remote teaching with high real-time requirements.

Misunderstanding 4. Ignore the art industry has specialization

Building a good video live broadcast system involves many preparations. This requires specialized streaming software and the cooperation of experienced technical engineers to implement such as input source processing, signal noise reduction, program task recording, station logo subtitles, linear broadcast For such functions, professional software and experienced experience are more needed. It is definitely not a buy of a capture card. It can be achieved through the free software that comes with the capture card or the free Windows Media Encoder.