基于 MPEG-4的视频编解码系统研究与实现

采用了专用 MPEG-4芯片(vw2010) 方案来实现 MPEG-4音视频编解码功能。首先介 绍了 VW2010的特点以及其工作原理，然后详细地阐述了以此芯片为核心的电路模块的设计，主要包括 编解码系统电路原理设计、接口设计、编解码工作原理及编解码流程等。最后就实现的编解码功能给予 分析与展望。     

在TMS320DM642上实现H．264的编解码器

介绍了H．264的原理和数字信号处理器TMS320DM642的外围电路接口,提出了一种基于TMS320DM642和Philips视频编解码芯片的视频处理系统的编解码设计思路,给出了其编解码系统的硬件设计、视频接口连接以及配置方法。     

基于DM642的嵌入式视频监控系统硬件设计

以视频编解码硬件系统及其实现技术为研究内容，以TMS320DM642为核心，结合TVPS150＆SAA7105视频编解码心芯片，设计了高性能的视频监控系统。详细说明了系统架构以及各功能模块，给出了各模块的硬件连接图，并结合实际设计中碰到的问题给出解决方法。最后在此基础上简要介绍了系统的应用前景以及功能扩展。     

总台亚太总站编解码传输系统工程实践

本文介绍了中央广播电视总台海外总站技术系统建设（一期）——亚太总站系统中编解码传输系统基本情况,包括设计理念、原则和方案等,以及临时编解码传输系统建设和运行过程中遇到的问题及解决方案。     

数字卫星电视接收机系统设计

首先扼要介绍了数字卫星电视（DVB－S）所采用的几项关键技术，包括信源编解码MPEG－2，复用，信道编解码，加扰，凋制解调等。然后扼要介绍了接收机设计中要解决的几个问题：如信道解调和解码、传输流解复用、音视频解码、网络信息管理及数据解码、用户界面及其他，并探讨了接收机方案选择及软硬件设计中要考虑的几个问题，如系统灵活性、可升级性及模块化设计等，并以熊猫数字卫星电视接收机系统的软硬件设计为例作了探讨。     

一种适用于窄带无线通信的语音编解码系统设计

语音编解码系统是无线双工语音通信设备的关键部件.介绍一种基于Xilinx ZYNQ7015的低速率语音编解码系统,通过部署于ZYNQ7015的软件结合语音处理芯片,完成语音信号的模数转换、压缩编解码及语音数据采集,获得速率低至2.4 kb/s的适合无线通信的声码话数据.设计具有硬件设计简单和可扩展性强的特点.     

基于FPGA技术的高速信道编解码芯片的优化设计

综述了目前国内外运用现场可编程门阵列（Field Programmable Gate Array，FPGA）进行数字电视高速信道编解码芯片开发的技术现状和发展动向。对技术“瓶颈”进行了分析，依据RS码（Reed-Solomon code）、卷积（Coil Accumulation，CA）编码和Viterbi编码和FPGA开发等技术，设计开发了一种具备自主知识产权的数字电视高速信道编解码芯片。它属于一种全新功能的应用级数字编解码产品，既可作为单元电路应用于数字电视系统，也可为实现数字电视高速信号处理的片上集成系统（System on Chip，SOC）设计提供模块电路。     

G.723.1语音编解码在FD216上的实现

介绍了ITU-T G.72 3.1标准和FD216的特征.分析了以FD216实现编解码系统的设计要点,设计了G.72 3.1实时语音编解码系统.该系统实现了ITU-T G.72 3.1标准包括附录A在内的全部功能,通过了所有测试矢量.     

数字信号处理及其通信系统设计

本文通过对数字信号处理器、外围支持系统、信号输入输出及其数字通信系统的综合分析讨论，总结了高速数字信号处理及其通信系统的一般设计原则和技巧，并以此设计了一个多速率的实时语音编解码及其通信系统，得到了良好的实际应用效果。     

TMS320VC54x处理器McBSP接口的设计和实现

以低速语音编解码系统为例．介绍了TMS320VC54x数字信号处理器的多通道缓冲串口的软硬件设计，给出了具体的设计思想和实现方法。     

A single-chip codec with switched-capacitor filters

A single-chip CMOS codec with filters has been developed using charge redistribution and switched-capacitor techniques. Its features are ~30 mm/SUP 2/ small chip area, 35 mW low power dissipation, and small 16 pin package. These are achieved with novel analog circuit techniques for A/D and D/A conversions and clock generation. Measured transmission characteristics meet the system requirements.     

基于AMBE-2000的数字语音传输系统

介绍了AMBE-2000的工作原理及其应用,并结合实例给出了数字语音传输系统中AMBE-2000与TLV320AIC10的A/D、D/A接口电路。AMBE-2000是DVSI(Digital Voice System·Inc)公司的语音压缩解压缩芯片,它采用AMBE语音压缩技术,具有语音音质好和编码波特率低、功耗低等优点;TLV320AIC10是TI公司的低功耗∑-Δ型16位A/D、D/A音频接口芯片。应用AMBE-2000的数字语音传输系统可以在低速率下提供优良的语音质量,并能实现全双工、实时语音压缩解压缩功能,因此在卫星通信、移动通信等领域有着广泛的应用。     

A monolithic ΣΔ A/D and D/A converter with filter forbroad-band speech coding

The authors present a 5-V-only 14-b, 16 ksamples/s linear codec suitable as the audio part of a CCITT G722 codec. The device uses second-order sigma-delta modulation for both analog/digital (A/D) and digital/analog (D/A) conversion at 2.048 Msamples/s. A time-continuous modulator with integrated antialias filtering is used at the A/D side, obviating the need for an external antialiasing filter. The digital filters for decimation and interpolation are implemented with both a custom digital signal processor (DSP) and specialized hardware. The device was realized with 74000 transistors on a 31-mm² die in a 3-μm SACMOS technology. A dynamic range of more than 80 dB and a passband ripple of 0.3 dB were attained with A/D and D/A paths in cascade     

A single-chip I/SUP 2/L PCM codec

A single chip CPCM codec is described. This chip, which is fabricated in bipolar technology, meets all the D3 specifications. The circuit is capable of operating in a fully asynchronous transmit and receive mode, and provisions are made for zero code suppression and A/B signaling. Even with this signaling, the codec achieves a worst case idle channel noise of 13 dBrnC0.     

双视立体视频同步合成系统设计与实现

以立体视频左右放置合成算法为核心算法,使用DDRSDRAM作为帧同步缓冲器件,采用FPGA作为平台,实现了一套立体视频合成系统。该系统降低了因制作立体视频需要处理两路带视差的视频而带来的对额外传输带宽和编解码器的需求,合成视频具有实时性好、失真小、立体感良好等特点。     

The implementation of digital echo cancellation in codecs

The architecture of a codec in which the echo cancellation is done in two stages, an analog hybrid to reduce the echo level at the input of the A/D converter and a programmable digital balance filter, is presented. The design problems connected with this architecture, such as the signal-to-noise performance of the A/D converter and the limiting effects of the variation of the analog components on the echo cancellation performance of the device and on the structure of the digital balance filters, are discussed. These results were used in the design of a single-power-supply CMOS device implemented in 1.5-μm technology using ΣΔ modulation techniques for A/D and D/A conversion. Its echo cancellation performance is sufficiently high that only one set of coefficients per national standard is necessary     

Digital DPCM Codec for TV Signals Based onDeltaM/DPCMDigital Conversions

A digital differential pulse-code modulation (DPCM) codec based on ΔM/DPCM and DPCM/ΔM digital conversions is presented as an equivalent replacement of a conventional DPCM codec for TV signals by using digital processing technology. A generalized model and equivalent circuit are shown for the digital DPCM codec, and transfer characteristics and quantizing noises are analyzed. The digital DPCM codec is designed for 1-MHz TV signals and the performance is verified by experiments. By the use of double integration ΔM and digital filter technology, it is shown that at the ΔM sampling rate of 16 MHz the overall SNR performance is sufficiently good for use as a conventional DPCM codec, and the digital code converters can be realized with commercially available transistor-transistor-logic (TTL) medium-scale-integrated (MSI) circuits and low-power emitter-coupled-logic (ECL) integrated circuits (IC's).     

Digital TV Receiver for NTSC Color TV Signals with Dual Word-Length DPCM Coding

A video codec system for carrying one broadcast quality NTSC color TV channel at a rate of 42.935 Mbits/s has been proposed. The receiver of the video codec system is developed for recovery of the original signal. The receiver accepts a 42.935 Mbits/s serial TDM data stream with a synchronous clock from the Transmitter. The receiver detects the unique sync code and inserts a horizontal blanking pattern which has been removed from the transmitting data. The audio and video data are separated at the outputs of the demultiplexer. The 4/8 bit dual length code word of the video data is smoothed out by a buffer memory and fed to the DPCM reconstruction loop. The analog NTSC color video signal as well as the audio signal are reconstructed after the D/A conversion. This paper describes the design and development of the receiver portion (Fig. 1) of the codec which is capable of transmitting'one color signal at broadcast standards on a T3 digital link.     

Class-AB high-swing CMOS power amplifier

A power amplifier for a loudspeaker and the earpiece of a telephone subset, integrated in the codec chip ARCOFI-SP (audio ringing codec filter featuring speakerphone function), are presented. The ARCOFI-SP is part of a subscriber telephone chip set. The analog section of the receive path comprises a low-noise programmable gain microphone amplifier with a maximum gain of 30-dB followed by a 16-b second-order sigma-delta analog-to-digital (A/D) converter. The analog section of the transmit path consists of two 16-b second-order sigma-delta D/A converters, one driving a pair of handset amplifiers for 200- Omega differential load and the other one a pair of loudspeaker amplifiers for 50- Omega differential load. The loudspeaker amplifier is described. A digital signal processor calculates the filter functions and handles frequency and tone generation. The amplifier has 1.2-mA quiescent current, 64-mA peak current, and >60 dB S/THD with 3.2-V output swing into a 25- Omega load.<>     

15/30 Mbit/s Universal Digital TV Codec Using a Median Adaptive Predictive Coding Method

This paper describes a 15/30 Mbit/s TV codec with a new approach to high-efficiency coding for TV signals, i.e., median adaptive prediction. The 15/30 Mbit/s codec, commonly applicable to NTSC, PAL, and SECAM (525/60 and 625/50) systems, uses adaptive prediction incorporating a motion-compensated interframe, an interfield, and an intrafield predictor. Its performance for digital transmission is presented. This universal codec is designed, based on CCIR recommendations concerning digital TV coding parameters for studios (Rec. 601) and general principles on long-distance digital TV transmission (Rec. 604). A field trial of 15 Mbit/s digital TV transmission using this codec between earth stations with a 30 m diameter antenna and a 5 m diameter antenna is reported.