Application design of FH8735 in audio and video compression card

1 Introduction

With the standardization of video surveillance products, ASIC solutions have gradually shown advantages in cost and stability. The FH8735 chip was launched in a timely manner for the audio and video compression card market. The FH8735 can support real-time encoding of two channels of 720P30 HD or 8 channels of D1 or 16 channels of CIF, greatly improving the integration of compression cards and reducing costs. At the same time, it further lowers the development threshold of hard compression cards.

2 Introduction to FH8735 H.264 Compression Chip

FH8735 is a high-performance H.264 compression chip that supports H.264 Main PROFILE and Baseline PROFILE video compression formats, and can perform eight-channel standard definition or two-channel 720p high-definition real-time compression encoding and multi-channel audio encoding. While encoding, it completes audio and video synchronization and outputs ES/PES/PS/TS.

In addition to high-performance video encoding capabilities, FH8735 provides a wealth of video pre-processing functions, such as de-interlace, de-noise, OSD overlay, scaling, motion detection, etc.

The video input interface of FH8735 can receive 8 standard BT.656 at the same time. The video input interface can also be configured as 2 high-definition video input interfaces as needed. FH8735 can receive digital video output from CMOS/CCD modules, video decoders, LVDS receivers and HDMI receivers. In addition, FH8735 can directly receive enhanced 656 video output by TW2815/TW2816.

FH8735 can receive eight-channel stereo audio input simultaneously, and can also be configured as 16-channel mono audio input according to application needs.

In order to configure the external video and audio receiving chips, FH8735 provides two completely independent standard I2C interfaces to deal with possible conflicts in the I2C addresses of external devices.

Typical applications of FH8735 include video conferencing systems, security monitoring and other fields that require high-resolution or multi-channel video encoding.

The system block diagram of FH8735 is shown below:

Figure 1 FH8735 system block diagram

Compared with other chips of the same type, the main technical advantages of FH8735 are as follows:

1) Super strong compression encoding performance

The H.264 encoding of FH8735 is completed by pure hardware, with the characteristics of high encoding capability, high encoding quality, low power consumption, etc. FH8735 supports dual streams, and the encoding capability can support up to 8D1+8CIF real-time encoding:

200fps D1+ 200fpsCIF @PAL

240fps D1+ 240fpsCIF @NTSC

The comparison results of typical video encoding show that at the same bit rate, the video encoding quality of FH8735 is close to that of JM11.0.

2) Video processing functions for video surveillance

In order to meet the special functional requirements of digital video surveillance, FH8735 provides flexible video encoding options and special digital video processing functions. Encoding parameters such as resolution, bit rate, frame structure, etc. can be modified while encoding. During the compression process, key frame output can be forced, frame rate, quantization coefficient, resolution, bit rate, frame structure can be changed without stopping or starting compression encoding. In addition, FH8735 supports multiple image processing functions such as de-interlacing, de-noising, multiple text and graphic OSD overlay, image reduction, motion detection, etc. for input video. It also supports capturing lossless original video signals for the host to perform some intelligent analysis and processing such as license plate recognition and face recognition.

FH8735 has two independent DDR controllers inside, which can connect to two external DDR SDRAMs. Configure one or two external DDR SDRAMs according to the actual system requirements for encoder performance.

3) Patented rate control technology

FH8735 provides four bit rate control strategies: fixed quantization coefficient (QP: quantisation parameter), constant bit rate (CBR: Constant Bit Rate), variable bit rate (VBR: Variable Bit Rate) and average bit rate (ABR: Average Bit Rate). Each algorithm has been carefully optimized and can adaptively pre-detect and judge the video scene, so as to ensure the subjective quality of the video while making the encoder output bit rate smooth and stable, ensuring the efficiency and stability of network transmission. In particular, the ABR algorithm has obtained a national patent certification due to its innovativeness and practicality.

3 Audio and video compression card solution based on FH8735

In order to speed up the early evaluation and development needs of customers, Fu Han provides an 8-channel D1, 16-channel CIF full-real-time and 16-channel D1 non-real-time audio and video compression card reference design based on FH8735. The compression card supports up to 16 audio and 16 video inputs, can complete audio and video acquisition, H.264 encoding, and send to the host through the PCI interface. The system diagram based on the FH8735 audio and video compression card reference design is as follows:

Figure 2 System diagram of audio and video compression card

The actual FH8735 audio and video compression card is shown in the following figure:

Figure 3 FH8735 audio and video compression card

The reference design includes FH8735 firmware, drivers supporting Windows XP/win 7 and Linux, Windows/Linux SDK and demonstration programs. The firmware can be modified to meet customized functions according to the user's specific application.

The Windows/Linux SDK implements the front-end video input type configuration of FH8735, encoding parameter settings, OSD text overlay, OSD graphic overlay, motion detection, area masking and preview YUV data acquisition, etc.

Compared with mainstream DSP solutions and ASIC solutions, the main features and advantages of this solution are as follows:

1) High cost performance

The single chip FH8735 can complete 8-channel D1, 16-channel CIF full real-time and 16-channel D1 non-real-time boards, which has obvious cost-effectiveness advantages compared to other DSP and ASIC solutions.

2) Short solution development cycle

The software and hardware design of this solution is simple. As for the software, the complex video and audio encoding is completely completed by hardware, and there are already stable drivers and SDKs. Customers can complete customized applications based on the drivers and SDKs. Therefore, the development cycle can be shortened and the products can be quickly launched to the market.

4 Conclusion

FH8735 具有单芯片8 路全D1 的H.264 实时编码能力，并提供针对视频监控的视频处理功能，能显著地提高客户产品性能，并减少开发时间，是目前监控市场最具竞争力的新一代高性价比视音频硬压缩板卡方案。FH8735 H.264 压缩板卡方案将会使硬压缩卡市场进一步普及和扩大。