Audio and video compression cards are important products for digital video surveillance, mainly including soft compression cards and hard compression cards. The soft compression card, because the PCI bus data throughput is too large, and the H.264 image compression processing is mainly performed by the CPU, resulting in poor stability. The main schemes of hard compression cards are DSP and ASIC schemes. The technical difficulty of DSP schemes is high and the development threshold is high; the early ASIC chips did not meet the special needs of the monitoring market, such as dynamic detection, time stamp overlay, screen occlusion, dynamic adjustment The frame rate, etc., made the early ASIC solutions in the compressed card products react flat.
With the standardization of video surveillance products, ASIC solutions have gradually shown advantages in terms of cost and stability. Fuhan Microelectronics has followed the trend of the security market and launched the FH8735 chip in time for the audio and video compression card market. FH8735 can support two 720P30 HD or 8 D1 or 16 CIF real-time encoding, which greatly improves the integration of compression cards, reduces costs, and further reduces the development threshold of hard pressure cards.
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. It can perform eight-channel standard definition or two-channel 720p HD real-time compression encoding and multi-channel audio encoding. While encoding, complete audio and video synchronization, output 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, zoom, motion detection, etc.
The video input interface of FH8735 can receive 8 standard BT.656 at the same time. You can also configure the video input interface as a 2-channel high-definition video input interface as needed. FH8735 can receive digital video output from CMOS / CCD module, video decoder, LVDS receiver and HDMI receiver. In addition, FH8735 can directly receive the enhanced 656 video output from TW2815 / TW2816.
FH8735 can simultaneously receive eight stereo audio inputs. It can also be configured as 16-channel mono audio input according to the needs of the application.
In order to configure external video and audio receiving chips, FH8735 provides two completely independent standard I2C interfaces to cope with possible conflicts of 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 in the figure below:
Compared with other chips of the same type, the main technical advantages of FH8735 are as follows:
1) Super compression coding performance
The H.264 encoding of FH8735 is completed by pure Hardware, which has the characteristics of high encoding ability, high encoding quality, low power consumption and so on. FH8735 supports dual stream, the encoding ability can support 8D1 + 8CIF real-time encoding:
200fps D1 + 200fpsCIF @PAL
240fps D1 + 240fpsCIF @NTSC
The comparison results of typical video coding show that at the same bit rate, FH8735 is close to the video coding quality of JM11.0.
2) Video processing function for video surveillance
In order to meet the special functional requirements of digital video surveillance, FH8735 provides flexible video encoding options and specialized digital video processing functions. You can modify encoding parameters such as resolution, code stream, and frame structure while encoding. During the compression process, you can force the output of key frames, change the frame rate, quantization coefficients, resolution, code stream, and frame structure without stopping and starting compression encoding. In addition, FH8735 supports multiple image processing functions such as de-interlacing, de-noising, multiple text and graphics OSD superimposition, image screen reduction, motion detection, and other input processing of the input video. It also supports capturing the original video signal without loss for the host to perform Some intelligent analysis and processing such as license plate recognition, face recognition, etc.
There are two independent DDR controllers inside FH8735, which can connect two sets of external DDR SDRAM. Configure one or two sets of external DDR SDRAM according to the actual system requirements for encoder performance.
3) Patented code rate control technology
FH8735 provides four kinds of code 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 to adaptively detect and judge the video scene in advance, so as to ensure the subjective quality of the video, and at the same time make the encoder output rate smooth and stable, to ensure the efficiency and stability of network transmission. Especially the ABR algorithm, because of its innovativeness and practicality, has obtained a national patent certification.
Audio and video compression card scheme based on FH8735
In order to speed up the customer's early evaluation and development needs, Fuhan provides 8-channel D1, 16-channel CIF full real-time and 16-channel D1 non-real-time audio and video compression card reference designs based on FH8735.
The compression card supports up to 16 channels of audio and 16 channels of video input, which can complete the collection of audio and video, H.264 encoding, and send to the host through the PCI interface.
The system diagram based on the reference design of the FH8735 audio and video compression card is as follows:
Figure 1: Schematic diagram of the audio and video compression card system.
FH8735 audio and video compression card is as follows:
Figure 3: FH8735 audio and video compression card.
The reference designs provided by Fullhan include Firmware of FH8735, drivers for Windows XP / win 7 and Linux, Windows / Linux SDK and demo programs, and firmware can be modified according to user specific applications to meet customized functions.
The Windows / Linux SDK implements FH8735's front-end video input type configuration, encoding parameter settings, OSD text overlay, OSD graphic overlay, motion detection, area masking, and preview YUV data acquisition.
Compared with mainstream DSP solutions and ASIC solutions, the main features and advantages of this solution are as follows:
1) High cost performance
FH8735 single chip can complete 8-channel D1, 16-channel CIF full real-time and 16-channel D1 non-real-time boards. Compared with other DSP and ASIC solutions, it has obvious cost-effective advantages.
2) Short program development cycle
The software and hardware design of this solution is simple. Because of the complicated video and audio coding, the software 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 quickly brought to market.
Summary of this article
FH8735 has a single chip 8-channel full D1 H.264 real-time encoding capability, and provides video processing functions for video surveillance, which can significantly improve customer product performance and reduce development time. Cost-effective video and audio hard compression board solution. The FH8735 H.264 compression board solution will further popularize and expand the hard compression card market.
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