Design and Implementation of H.264 codecs Based on Hi3510

Design and Implementation of H.264 codecs Based on Hi3510

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Source: Electronic Technology Author: Zhang Xinan

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As the global audio and video (AV) field continues to rapidly convert from analog to digital, digital televisions, DVD players, digital static image cameras (DSC) that support Digital Audio and Video Processing) the number of new consumer electronic devices, such as digital video recorders (DVC), also keeps rising rapidly. The huge information flow brings us a wealth of human culture and troubles for storing information. Especially the huge data of video information has given rise to the demand of video compression technology. Video compression technology has become one of the most popular technologies in the multimedia era, and is widely used in video, movie, videophone, video conferencing, remote monitoring and other image transmission and storage fields.

1 H.264 Introduction

H. 264 is the latest coding standard jointly developed by ITU-T and ISO/IEC, which was first proposed by the ITU-T in 1997 with the goal of proposing a higher performance video coding standard than H.263 at the time. Compared with other standards, H.264 has the following features:

(1) low bit rate. Compared with the compression technology such as MPEG-2, in the same image quality, the data size after compression using H.264 technology is only 264 ~ of the MPEG-2 ~ 1/3. Obviously, the use of H.264 compression technology will greatly save storage capacity, channel bandwidth, user download time and data traffic charges.

(2) high image quality. H.264 provides continuous and smooth high-quality images.

(3) wide application scope. Different H.264 profiles can be applied to real-time communications with strict latency restrictions, or other applications with low latency requirements (such as video storage and streaming media ).

(4) robustness. H. 264 during the design, a tool for packet switching networks, such as packet loss in the Internet, and bits in wireless networks, was proposed to enable H. 264 enhanced anti-code performance during propagation in these networks.

(5) network friendliness. The NAL layer is added in H.264 to adapt the output code stream of the encoder to various types of networks, thus providing friendly network interfaces.

H.264 achieves the above performance because it adopts the following advanced technologies:

The first is intra-Frame Prediction encoding, which makes full use of the image's spatial correlation to reduce the bit rate. According to the image encoding type, you can select one of several encoding types for each macro block. There are 13 prediction modes (4x4 blocks, 9 models, 16x16 blocks, 4 models), which were none of the previous standards.

The second is the adoption of the new fast moving valuation algorithm UMHexagonS (China Patent), which is a calculation method relative to H. 264 the original fast and full search algorithm can save more than 90% of the new algorithms. It is called the unclassified rical-cross muti-hexagon search algorithm ), this is an all-pixel motion valuation algorithm. Because of its high bit rate and high motion image sequence encoding, it has a very low computational workload while maintaining a good distortion rate, and has been officially adopted by H.264. H.264 has seven block matching modes, which are calculated one by one during encoding and the optimal one is selected. For example, the finer part uses 4x4 blocks, and the non-moving background can use 16x16 blocks. In the past, there was only one or two fixed block size models. H.264 uses multi-frame reference to maximize the use of real-domain relevance. The reference frame can range from 1 frame to 15 frames. In the past, the standard was a single frame reference. There is also a 1/4 or 1/8 precision sub-object motion estimation, the previous standard uses up to 1/2 precision sub-object search, and is not a required option. In order to eliminate the block effect that often occurs in video encoding, H.264 uses a deblocking filter.

H.264 also adopts integer DCT transformation to increase the conversion speed. New entropy coding methods such as CAVLC and CABAC are used to improve the encoding effect.

The H264 standard makes Motion Image Compression Technology rise to a higher stage, and providing high-quality image transmission at lower bandwidth is a highlight of H.264. H.264 because of its low transmission bit rate and low storage requirements, the basic system does not need to use copyright, has an open nature, is expected to replace MPEG-2.

2 Hi3510 Working Principle

Hi3510 is based on H. 264 BP algorithm video compression chip, which adopts the multi-core high-integration SoC architecture of ARM + DSP + hardware acceleration engine, and has powerful video processing functions. It can realize real-time Encoding of DVD quality, adapt to various network environments in white, ensure the definition and real-time of the picture, and reduce the bit rate. 264 encoding technology greatly reduces network storage space and ensures network security by integrating the DES/3DES encryption/Decryption hardware engine.

Hi3510 adopts 0.13 μm technology and LFBGA400 encapsulation. The size is 19 × 19mm and the pin spacing is 0.8mm, the chip integrates interfaces including digital video interfaces, USB, ETH, I2S, I2C, GPIO, SPI, UART, SDRAM, DDR, etc, the BOM cost of devices can be greatly reduced when devices are developed in various application scenarios.

Operating principle of Hi3510: video input units receive digital video information output by VADC through the ITU-RBT.601/656 interface, the original image received is written to the external memory (sdr sdram or ddr sdram) through the AHB Bus. The video decoder reads the image from the external memory for motion estimation (Inter-Frame Prediction), intra-frame prediction, DCT transformation, quantization, entropy encoding (CAVLC + Exp-Golomb), IDCT transformation, reverse quantization, motion compensation, and other operations. 264 the Protocol's bare code stream and encoded reconstruction frame (as the reference frame of the next frame) are written into the external storage; the video output unit reads the image data from the external memory and sends the data to the VDAC through the ITU-R BT.601/656 interface. The video output unit reads different image content from the external memory according to different application requirements, when you need to preview the input image, the video output unit reads the original image from the external storage. When you need to observe the encoding effect of the video encoder, the video output unit reads the encoded reconstruction frame from the external storage; ARM encapsulates the protocol stack of the bitstream output by the video encoder and sends it to the network port to implement Apsaravideo for Vod.

H of Hi3510. the 264 Audio/Video Codec SoC logical Diagram 1 shows that the chip consists of the core of ARM + DSP + video codec accelerator + graphics engine zooming, and integrates a wide range of peripheral interfaces, in addition, it integrates algorithms such as digital watermarks and DES/3DES, so that a single chip can adapt to almost all work and reduce the development difficulty of cooperation with other chips, the vendor is also exempt from repeated development of standard parts such as algorithms, which greatly reduces the investment threshold of the device manufacturer. With the Development kits of different applications of haisi, various products such as PMP, videophone, network monitoring, PVR, and video intercom can be developed.

3 Hi3510 codec Design Scheme

As a SoC-based Codec Chip, Hi3510 fully considers compatibility and ease of use during design. Supports almost all AD/DA chips produced by companies. Hi3510 can be used as an independent encoder, an independent decoder, or a codec at the same time, fully considering the various application scenarios in the codec market. Hi3510 is a typical multi-application single-chip solution that greatly reduces the BOM composition and cost of devices.

The simultaneous codec design scheme 2 of Hi3510 is shown in.

4 Hi3510 CODEC Application

Hi3510's Linux operating system (supporting open operating systems such as Vxworks and WinCE at the same time) and ARM processor enable the chip to develop many application functions in addition to the codec function. In Figure 2, the digital compression, storage, and transmission of compound video signals can be achieved by attaching a common AD. The Hi3510 Development Kit provides upper-layer APIs to call and implement all chip functions and develop its own personalized functions.

The encoding Application Design of Hi3510 chip is shown in 3.

The decoder is used in the same architecture design as the encoder (convenient solution can maintain consistency, and a set of hardware can meet different requirements, only software upgrade is required ). The decoder only needs to be equipped with a DA chip (which can be saved if it is an LCD digital screen) to decode the data stream, in addition, user-computer interaction menu operations are implemented through GUI or OSD to implement product applications with similar functions such as PMP.

The Application Design of decoding Hi3510 chip is shown in Figure 4.

H.264 standard applications provide technical support for video network transmission, especially low-bandwidth transmission (such as wireless transmission. In today's information explosion, the market requires designers to launch products faster and faster. In order to maintain product competitiveness, they must maintain sufficient advantages in product prices and features of product applications, especially in the Multi-coal market. Based on the standard algorithm provided by the SoC chip of hith, it gives designers the maximum flexibility to design suitable products, greatly reducing the investment cost of the manufacturers, it shortens the time for manufacturers to launch new products and prepares to win the market. In recent years, every portable personal electronic device seems to be equipped with audio and video functions, including mobile phones, portable media players and PDAs. This cost-effective H.264 codecs Based on Hi3510 will certainly have broad market prospects.