Application of FPGA in Broadcast Video Processing

1. Timing

The demand for broadcast video systems is increasing significantly year by year around the world, due to the following factors:

• The increase in the number of broadcast channels available to viewers has increased from a handful of channels to hundreds of channels available to more viewers around the world.

• The development of cable and satellite TV transmission networks and the development of Internet broadcasting have brought us into the era of "million channels".

• The development of small-scale broadcast video applications within companies and on a small scale for information exchange, training and security protection. There has also been considerable development in the entertainment industry, such as hotel video on demand and large-screen electronic display screens.

• Delayed video playback and quasi-video on demand have greatly increased the convenience of user use, making users want more channels.

• Today, the development of large-screen TV from ordinary TV to high-definition TV requires us to install more broadcasting equipment.

• The content of videos is increasing rapidly. Additional special effects, multiple windows, subtitle overlay, replay and other functions require higher performance broadcast equipment.

• The abundance of video resources. Previously, video could only be produced in special studios and for reporting major events, but it can now be produced in every community and business. The number of video resources has grown rapidly, and a whole new market for low-end broadcasting equipment has emerged.

• The rapid transition to digital television has resulted in the replacement of older analog signal systems.

• As the digital television revolution has taken place, there has been a strong need to convert video codes between various digital signal specifications, which has led to the need to add broadcast equipment, including:

• Basic specifications: uncompressed, time-compressed, MPEG2, MPEG4, H.264 compression, Windows Media9, Real Networks, etc.

• Image size: standard definition (SD), high definition 720P, high definition 1080P;

• Transmission/packaging specifications: ATSC/DVB, SDI, IP, etc.;

• Audio specifications: AES3, etc.

• International standards: NTSC, PAL;

• Device interface: 1394 FireWire interface, DVI interface, GigE Ethernet interface;

These latest changes have made powerful broadcast video equipment necessary. Broadcast equipment requires stronger processing capabilities, more output channels, more output specifications, and a wider range of applications.

This paper discusses a new product platform that will meet future needs. The product cost and development cost of this platform will be lower than that of existing systems.

2. Video system platform

First, let us investigate some video broadcast systems and video platforms used today. Generally speaking, the basic processing used for video production and distribution includes the following aspects:

Content production: camera production and computer production; editing/image overlay/image mixing; special effects; video quality enhancement; video signal format conversion; video storage. Video

extraction and distribution: video extraction specification conversion; insertion of program information and advertisements; broadcast video specification conversion; distribution: normal, delayed playback, video on demand.

Today, the platforms used to complete the above video functions can be roughly divided into the following types:

2.1 Content production platform

Because the content production platform is a non-real-time system, there is no high performance requirement, even if the processing time is longer than the actual time. Therefore, ordinary computers and workstations can do the job. Usually, these platforms are used together with a video accelerator board, but this accelerator board is only used to improve the work efficiency of video production personnel, not for real-time processing needs.

2.2 Video Extraction and Publishing Platforms

Video extraction and publishing platforms must be synchronized with video broadcasting, and all processing must be completed within the line frequency and frame rate of video broadcasting, so there are absolute high performance requirements. Reliability is also an inevitable requirement for these processes.

In order to meet these requirements, most of the video extraction and publishing platforms used today are built on the manufacturer's professional broadcasting platform. This platform consists of several special function modules built on professional equipment.

Some manufacturers have begun to use low-cost personal computers for real-time video processing, but this is only limited to processing some limited peripheral functions and has not become the mainstream of video extraction and publishing systems.

It is already very clear that PC-based platforms will gradually play an increasingly important role in video extraction and publishing systems. These platforms will have broad application prospects due to the following reasons:

• Outstanding performance-price ratio brought by large-capacity processing;

• Standard platform that can be used by different application software manufacturers, with better functions and lower costs;

• Higher performance-price ratio and more functions;

3. Strengths and limitations

of PCs PCs are becoming increasingly powerful and can now process single video streams in real time, compress single video streams, store them on a hard drive, decompress and play standard quality streams. However, the bandwidth of PCs is far from sufficient to handle the processing of many uncompressed video streams, processing of terminal video distribution, live broadcast processing and other high-quality video processing.

Currently, the difficulty in processing uncompressed video lies in resolving the contradictions of countless professional processing boards from various manufacturers. These professional processing boards can perform their specific functions, but cannot flexibly add new functions, and when you need multiple functions, you need to coordinate completely different processing boards from different manufacturers.

What the market needs is a flexible platform that can process uncompressed video on a PC. It can provide the processing power of professional equipment like high-end systems and the low price of low-end PC systems.

4. FPGAs in video processing

FPGAs (field programmable gate arrays) produced by Altera or other companies are a very fast-growing semiconductor chip. Over the past 10 years, these chips have been widely used and their performance has been continuously improved. They now have a $2 billion market and are widely used in communications, military and broadcast equipment.

FPGA chips have the ability to provide programmable software and the processing performance of professional hardware. In video applications, FPGA chips can provide up to 10 to 100 times the processing power on a personal computer platform, and when users need to change the function of the system, they only need to re-download a file to modify the user's hardware configuration, and the user's hardware upgrade can be completed in 1 second.

Although FPGA technology has long been used in the broadcast video industry, so far, such applications have mostly been limited to specific functions on professional platforms, and only a few have been applied to specific functions on personal computer PCI boards.

Despite this, the processing power of FPGAs has developed rapidly in recent years. It has now evolved to the point where one chip can perform the functions of a board, or one chip can perform the functions of a system (SoC). Because multiple FPGA chips can be installed on a PCI board, it is possible to develop a complete system equivalent to a professional device on one board.

In addition, under existing technology, standard video processing function modules can be downloaded to a new high-processing FPGA chip. These modules are like multiple functional modules in a professional device. In other words, now one chip can contain the entire system, instead of having to be implemented by a professional device as before.

This development method has the following advantages over developing professional equipment systems: much lower development costs; much lower system costs; extremely convenient user design and upgrades; and direct use of application software on the personal computer platform.

5. Develop a "personal computer + FPGA" platform

When designing a video system using the "PC + FPGA" algorithm, the most important decision is which processing runs in the FPGA and which runs on the PC. Generally speaking, the best system design is for all high-speed data streams to pass through the FPGA and not through the PC. The PC can be used for data stream management and some lower data output functions, such as inserting overlay data.

The following types of processing are suitable for FPGAs to achieve the best performance: video mixing/overlay; synchronous compression/decompression; data format conversion/transcoding; IP, DVB/ATSC specification packet/stream processing for multi-channel simultaneous output systems; video extraction, decompression, multi-channel broadcasting; video enhancement: noise reduction, color stabilization, resolution enhancement, etc.; video, audio and other data stream processing.

Boards based on a single FPGA chip can handle a total bandwidth of up to 500MB (equivalent to one high-definition uncompressed data stream or four standard-definition uncompressed data streams).

If the user needs, a PC can carry multiple processing boards, and a tower rack-mount server can contain multiple PCs.

This design method has a wide range of applications, from small personal computers that can handle a few SDI data streams to tower servers that can handle hundreds of data streams.

6. Application of the "personal computer + FPGA" platform

Using the above "personal computer + FPGA" platform algorithm, low-cost, high-efficiency solutions can be provided for the following types of applications: local network, entertainment, World Wide Web, cable TV video on demand server; scheduled replay server; delay; live video production of sports programs and other programs; ATSC/DVB data broadcasting; community service systems, local news/weather forecasts, cable online shopping; Internet cooperative communication channels; multi-channel satellite receiving equipment; program production and advertising insertion equipment; regional video distribution system.

7. Introduction: Tsunami Video-on-Board Platform

Avvida's Tsunami PCI board and Wave development kit allow users to quickly develop and mass produce their products.

The Tsunami broadcast processing board includes: up to 6 SDI interfaces; up to 5 FPGA chips, each with 4 high-speed memories, capable of implementing a variety of video processing functions; high-bandwidth memory access to the PC via the PCI bus; a digital video input interface, with a transfer rate of up to 300Mbps from the PC to the Tsunami broadcast board.

Avvida can provide the following video processing function modules: format conversion between SDI RAW video format and 4:4:2, YUV, YcrCb, and other synchronous compression formats; sampling from 4:4:4 to 4:4:2 format; color space conversion: RGB format to YUV format; video and audio overlay and mixing; SDI input/output processing and error detection (EDH) insertion and extraction; synchronous phase lock; MPEG2, MPEG4 and other compression/decompression specifications; SDI input signal storage; stored content replay; and others.

8. Conclusion

The demand for more powerful digital video broadcasting systems is growing rapidly, which is both a new challenge and a new opportunity for a system with broad application prospects. A standard personal computer equipped with Avvida's powerful Tsunami FPGA PCI processing board can effectively meet the market demand. The FPGA-based video processing function module attached to the processing board can bring users lower development costs and faster time to market.