Ten years of sharpening a sword, American giant video site Hulu's Live system architecture practice

Hulu is a U.S.-listed online video company in 2007, offering subscription-based video services with a business model similar to the domestic love-odd art and Youku. Hulu released the latest OTT live TV app--hulu in May this year, with the aim of replacing the traditional cable TV service, and the recent emergence of live broadcast applications such as YY, Ying, etc.

This paper mainly shares the three aspects of Hulu's existing video system, the Hulu OTT live application and the DASH-based live broadcasting system, which will involve some difficulties and experiences in the process of building live broadcast based on VOD.

Hulu's existing video system

Hulu Terminal and video content

Hulu applications can be accessed on televisions, computers, mobile devices, and even game consoles, such as:

650) this.width=650; "Src=" Http://s3.51cto.com/wyfs02/M02/9D/DC/wKiom1mH2EbSaArgAAC-rEBf_xc166.jpg-wh_651x-s_ 2428466839.jpg "title=" "border=" 0 "/>

Hulu started out as a Web site, and over time, especially in the American family's living room, where users often watch video, Hulu is constantly developing and adapting to the hardware that plays the video. On-demand content is mainly television, film, home-made drama, children's programs and other professional production content.

Hulu business model

Hulu has two main business models, one is to obtain profits through video advertising, and one is to earn profits through registered members .

is an example of a movie ad. Not only are there common video ads, there are also parts that can interact directly with users, prompting users to click to buy movie tickets. Over the years, Hulu has tried a lot in AD mode, including a lot of interactive forms on the living room device.

650) this.width=650; "Src=" Http://s3.51cto.com/wyfs02/M00/9D/DB/wKioL1mH2F3TAp-dAADD5gt4-ao688.jpg-wh_600x-s_ 1368782387.jpg "title=" "border=" 0 "/>

In addition to advertising, the membership system is also the main way Hulu profit. By registering members, paying membership fees, users can enjoy the latest, most full TV shows.

challenges and key technologies for on-demand systems

Digital Video Supply Chain

The video supply chain section, although users can not directly see, but will give users a direct impact. Hulu's bigger selling point in the US market is television broadcasts, and the next day it can be synced online.

This seemingly simple demand behind, but the front of the entire processing cycle requirements are very high, such as on-line speed, management of the user's viewing time, and so on, each link should be done. In the face of the challenges posed by the supply chain, Hulu has built a full video transcoding system, which is addressed by this distributed cluster.

Multi-platform Video services

Faced with the challenges of multi-platform playback, Hulu built a multi-platform video service, home-made players, to ensure that the normal playback on each platform, with a unified video stream can support all platforms.

There is also a unified video format based on DASH, its scalability, packaging efficiency and other aspects also excellent performance.

Content Protection

Hulu has built a multi-DRM video system based on DASH and CENC, guaranteeing different platforms, using a unified, encrypted video source even with different DRM systems.

AD insertion

If the network is not good, inserting ads may result in video re-buffering, which can have a bad impact on users. Hulu's approach is based on the DASH XLINK dynamic ad insertion mechanism, which can be combined on the stream, the player preloaded in real time, without the need to switch players, streams and other operations.

Video Playback Quality Assurance

In order to ensure the quality of video playback, Hulu has established a quality assurance system for video playback, which includes the client can do adaptive dynamic stream switching, multi-CDN automatic switching, real-time video QOS monitoring and response system.

existing on-demand video system architecture

For example, a system architecture around on-demand products :

650) this.width=650; "Src=" Http://s4.51cto.com/wyfs02/M02/9D/DB/wKioL1mH2ISgTFnZAACjedHbuTI604.jpg-wh_600x-s_ 2541082036.jpg "title=" "border=" 0 "/>

There are many online video architectures that are basically similar, but Hulu's special place is:

U.S. content manufacturers have high content security requirements, requiring all content must have DRM encryption mode, so there is a relatively complete DRM license, to ensure that all content is safe to play.

In the important advertising section, the Ad Server is placed separately to ensure that users have a good advertising experience, to prevent long, repetitive ads.

Hulu OTT Live app

OTT is a new live broadcast application of Hulu, which adds many modules on the basis of on-demand, but also has a lot of difficulties to overcome.

As below, is the demand of the live system:

• HD, high frame rate live.

• As close to the IPTV experience as possible: low latency, fast start, and switching.

• 24x7, uninterrupted live streaming service.

• Live content close to the on-demand experience.

DASH-based Live system

To meet the needs of OTT live applications, Hulu has developed a set of live systems based on DASH.

As follows, is a simple architecture diagram:

650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M00/9D/DC/wKiom1mH2O3wpL_UAACuMUE-yWQ383.jpg "title=" " border= "0"/>

CP connection stream via TS over RTP, the content is sent to the multi-bitrate live encoder, encoder output 6 to 8 different bitrate, the lowest 128K, meet the low bandwidth intensity of the user's use.

After that, enter the encapsulation and encryption link, packaged into Apple and DASH format. On the one hand, time information and metadata are stored in the real-time database for MPD generation. On the other hand, the actual data files are encapsulated, cut into small pieces by time, uploaded to the source station, and then to the CDN.

When the client player is ready to start playing, learn from the MDP server which videos can be played and get the actual video files through the CDN.

Challenges of building a live broadcast system

In the process of building the live Broadcasting System, Hulu overcomes the difficulties from all sides. The following mainly share the "on-demand" live broadcast, instantaneous user explosion and user viewing quality of the three challenges.

"On-demand" live

Hulu hopes to achieve on-demand results during live streaming. At the same time, you can watch the previous video, such as:

650) this.width=650; "src=" http://s1.51cto.com/wyfs02/M02/9D/DC/wKioL1mH2SChU_OPAADDo5KXmTA814.jpg "title=" " border= "0"/>

In order to achieve this on-demand usage patterns, Hulu uses the DASH video format to respond.

The main thing is to do the following:

• time and time information is stored in Manifest. MPD Not only describes the video itself, but also describes what happened, such as whether it is now playing ads, etc., which are stored in the Manifest way.

• using video splitter, short shard transmission, the audio is split out. This enables switching between multiple bitrate to be transferred to any playback position at the same time.

• full platform coverage. support for almost all client devices such as Web pages, living room devices, mobile devices, and more.

For example, is the DASH format:

650) this.width=650; "src=" http://s5.51cto.com/wyfs02/M00/9D/DC/wKiom1mH2TnRVTf_AAC2JGSu1oY800.jpg "title=" " border= "0"/>

Instantaneous user explosion

Dealing with instantaneous user live streaming is the thing that most live platforms will encounter, Hulu is no exception, online such things are very common, a popular show, such as HBO's new Game of Thrones, traffic will show more than 10 times times the growth.

The most effective way to deal with this situation is to improve system elasticity and scalability. The solution has a built-in microservices architecture, mainly in the following ways:

• Load Balancing. With three data center nodes worldwide, load balancing can be carried out between each node.

• Micro-service Framework. The extensible MicroServices Framework based on Docker is simple as follows:

650) this.width=650; "src=" http://s1.51cto.com/wyfs02/M02/9D/DC/wKiom1mH2ZbiiIiiAABT1IT_mz0119.jpg "title=" " border= "0"/>

Take advantage of public cloud load resistance.    When the data center load is found to be unsustainable, it overflows to the public cloud. Full-service Status monitoring alarm system. When any of the services found RPS and other changes, the alert will be issued, and the OPS staff would take care of the first time.

There are multi-CDN automatic traffic allocation mechanism, the highest level is the artificial rules, according to the current domestic use situation adjustment ratio. When an actual CDN access failure occurs, the Fallback is used to another CDN, and the other client has automatic traffic allocation algorithm tuning.

User Viewing quality

How do we ensure that the quality of the video is viewed by the user? For example, how to make sure not to black screen? Hulu has built a real-time video quality monitoring system that buries the relevant modules in each client, and the module collects key metrics.

For example, a real-time video quality monitoring flowchart :

650) this.width=650; "Src=" Http://s1.51cto.com/wyfs02/M02/9D/DC/wKioL1mH2aOgy3gBAABVzh_tm7s625.jpg-wh_600x-s_ 1999566583.jpg "title=" "border=" 0 "/>

Part uses the SBAK real-time event processing method, enters the QOS to carry on the next processing. In addition, real-time processing of the module will eventually join Elastic Search.

In this way, the buffer rate, the average bitrate, the live delay and so on can be observed. For example, different colors are actually things that are responsible for different teams.

For example, the entire process of the monitoring of all SLAs, a service monitoring, green representation of the situation is better, red indicates that there is a problem, the number becomes larger will attract attention. There are a variety of indicators, basically all systems have such a corresponding monitoring system, each team can see the overall situation of their team.

650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M01/9D/DC/wKiom1mH2baAsP4LAACu5TNXCI0458.jpg "title=" " border= "0"/>

The above content according to Li bin teacher in WOTA2017 "high-performance Broadcast System Architecture" session content finishing. Focus on architecture, algorithms, operations and other technical fields, there are submissions, seeking to report the intention of technical people please contact [email protected]

650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M01/9D/DB/wKioL1mH15WTKA-aAABb7XAYec0991.jpg "title=" " border= "0"/>

Leading the development of Hulu Core video technology, participated in and dominated the Hulu multi-platform DASH player, video playback quality monitoring and analysis system, OTT MVPD system. He has been engaged in the research and development of Internet video related fields since Dr. Tsinghua University. Beijing Flashing Technology Co., Ltd. was the director of Technology, the company produced the "Dopool Mobile TV" Client cumulative activation download volume over billion.

650) this.width=650; "src=" http://s5.51cto.com/wyfs02/M00/9C/4C/wKiom1luyAXhf-_QAACSsaar_g4853.jpg "title=" " border= "0"/>

This article is from the "12562290" blog, please be sure to keep this source http://12572290.blog.51cto.com/12562290/1954165

Ten years of sharpening a sword, American giant video site Hulu's Live system architecture practice