MPEG-4 Video and Image Coding on Digital Signal Processors

The emerging MPEG-4 standard encompasses a wide variety of applications, many of which are suitable for implementation on a Digital Signal Processor (DSP). In particular, consumer products with embedded multimedia capability, such as set-top boxes and wireless communicators, are suitable for DSP-based implementation. With a programmable approach, various algorithmic tradeoffs can be made, based on processing capability. For best performance, careful attention must be paid to memory allocation, data transfer, and ordering of instructions to best match the DSP architecture. We discuss implementing simple profile MPEG-4 video on the low-power TMS320C54x, core profile on the TMS320C6x, and scalable texture profile, which could be implemented on either processor family.     

Speech coding in mobile radio communications

Speech coding, the efficient representation of speech in digital form, is one of the key technologies in current and evolving digital cellular and wireless voice communications offerings. The speech coders in existing standards exhibit a level of sophistication and performance unimaginable just 15 years ago. We outline the characteristics of the mobile communications problem with respect to speech coders and point out the principal issues in speech coder design for these applications. Speech coding methods in existing mobile communications standards are described and contrasted. The limitations imposed by the wireless channel and by background impairments are discussed, and approaches to addressing their resulting effects are presented. Suggestions for future research in speech coding for the mobile communications problem are outlined     

Real-time image and video processing in portable and mobile devices

Mobile handheld and battery-operated consumer electronic devices such as digital still cameras, personal media players, digital camcorders, camera phones, mobile video telephones, etc. have become very popular and their annual shipments are already in hunderds of millions of units. The ability to carry out image and video processing in real-time has been one of the major reasons for the widespread success of these devices. In this article, the typical components present in such devices and the image and video processing that are carried out are described first. Some of the emerging trends relevant to image and video processing algorithms used on these devices are highlighted next. A brief overview of system requirements and challenges for image and video processing on these devices is then provided. These requirements are driving image and video processing research in new directions.     

基于DSP的数码相机中的MPEG-4压缩技术

~~基于DSP的数码相机中的MPEG-4压缩技术$德州仪器公司集团实验实~~     

A fast feature-assisted adaptive early termination approach for multiple reference frames motion estimation in H.264

The multiple reference frames motion estimation approach used in H.264 is computationally intensive. This paper presents a fast or computationally efficient feature-assisted adaptive early termination approach in order to reduce the computational complexity while maintaining more or less the same video quality. The introduced feature-assisted approach consists of three parts: (1) reduction of the number of available reference frames using predicted motion activity, extracted texture information, and skip mode from neighboring macroblocks, (2) the most probable reference frame prediction based on neighboring macroblocks, and (3) an adaptive early termination threshold derived from a theoretical analysis of all zero block detection. Extensive experimental results are performed to demonstrate the computational gain of the introduced approach over the standard approach for the multiple reference frames motion estimation.     

Multiframe video coding for improved performance over wirelesschannels

We propose and evaluate a multi-frame extension to block motion compensation (BMC) coding of videoconferencing-type video signals for wireless channels. The multi-frame BMC (MF-BMC) coder makes use of the redundancy that exists across multiple frames in typical videoconferencing sequences to achieve additional compression over that obtained by using the single frame BMC (SF-BMC) approach, such as in the base-level H.263 codec. The MF-BMC approach also has an inherent ability of overcoming some transmission errors and is thus more robust when compared to the SF-BMC approach. We model the error propagation process in MF-BMC coding as a multiple Markov chain and use Markov chain analysis to infer that the use of multiple frames in motion compensation increases robustness. The Markov chain analysis is also used to devise a simple scheme which randomizes the selection of the frame (amongst the multiple previous frames) used in BMC to achieve additional robustness. The MF-BMC coders proposed are a multi-frame extension of the base level H.263 coder and are found to be more robust than the base level H.263 coder when subjected to simulated errors commonly encountered on wireless channels.