Enhanced Variable Rate Codec

About: Enhanced Variable Rate Codec is a research topic. Over the lifetime, 357 publications have been published within this topic receiving 4842 citations. The topic is also known as: EVRC.

The study of video acquisition and compression codec system based on DaVinci

Abstract: This paper achieves the design of a video acquisition and compression codec system, which takes dual-core chips TMS320DM6446 as its core and Linux as its operating system. This is because Linux can be reduced and transplanted. The video capture device driver V4L2 and Codec Engine are introduced in detail, and through H.264 algorithm functions of video compression codec are successfully realized. Relevant experiments show that the codec algorithm has strong performance of anti-errors and the videos are clear and reliable after compression codec. Moreover the mount of the video data is largely reduced.

FEC-based packet loss recovery for AVS-M audio codec

Abstract: In this paper, we utilize sender-based Forward Error Correction (FEC) techniques to enhance the robustness of packet loss recovery for AVS Mobile speech and audio (AVS-M) codec. Two FEC schemes are proposed which take the advantage of the codec's structure characteristics and do not introduce extra delay. The objective and subjective listening tests results show that the two methods achieve higher reconstructed quality than the codec's original frame erasure scheme in the case of packet loss.

A Multiprocessor Based Low Bitrate Video Codec Architecture and a Well-Adapted Two Phase Software Coding Strategy

Abstract: The first part of the paper describes a specialized multiprocessor environment for hybrid coding of visual communications signals in the range from ISDN basic access to primary rate transmission channels. Most important is a proprietary 4-wide SIMD parallel video processor with 80 MIPS. The second part deals with the software philosophy of the codec. It uses preanalysis and prebuffering in the first phase of coding a frame. In the second phase, limited processing power and available channel bits are distributed optimally over time and over changed areas of one frame. Codec delay is halved with respect to conventional codecs.

Bandwidth scalable codec and control method thereof

Abstract: The present invention relates to a bandwidth scalable codec and a control method thereof. The control method of the bandwidth scalable codec supporting different frequency bands according to the present invention includes checking whether bandwidth switching has occurred by comparing bandwidths of signals corresponding to respective frames of an input signal, computing an interval of a bandwidth switching section and comparing the interval with a preset threshold value, when bandwidth switching has occurred, and controlling a frequency band of the input signal on the basis of the threshold value comparison result and increase or decrease of bandwidth in the bandwidth switching section. The bandwidth scalable codec lessens sound deterioration caused by a sudden bandwidth change, to thereby improve the overall quality of voice communication.

Enhancements to RTP Payload Formats for EVRC Family Codecs Status of This Memo

Abstract: This document updates the Enhanced Variable Rate Codec (EVRC) RTP payload formats defined in RFC 3558 with several enhancements and extensions. In particular, it defines support for the header-free and interleaved/bundled packet formats for the EVRC-B codec, a new compact bundled format for the EVRC and EVRC-B codecs, as well as discontinuous transmission (DTX) support for EVRC and EVRC-B-encoded speech transported via RTP. Voice over IP (VoIP) applications operating over low bandwidth dial-up and wireless networks require such enhancements for efficient use of the bandwidth.