Topic
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.
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27 Jun 2005
TL;DR: Experimental results demonstrate that the proposed PL-based RDA compares well against other rate selection techniques in terms of average bitrate and speech quality.
Abstract: In this paper, we describe a perceptually-motivated rate control algorithm for variable bit rate (VBR) speech coding. Unlike the existing rate selection strategies that are based on statistical metrics, the proposed method employs a perceptual loudness (PL) measure. The VBR speech standard TIA IS-127 enhanced variable rate codec (EVRC) has been chosen as the test-bed for evaluating the performance of the PL-based rate selection strategy relative to three other existing methods. In particular, the comparative study includes the following rate determination algorithms: voice activity detection, speech frame energy-thresholding, and phonetic segmentation. Experimental results demonstrate that the proposed PL-based RDA compares well against other rate selection techniques in terms of average bitrate and speech quality
Patent•
02 Jul 2008
TL;DR: In this paper, the transmission power is set in a power control state in response to a current signal quality measure and in a rate control state wherein speech transmission is controlled by switching the speech rate.
Abstract: In a method and mobile station for transmitting speech data using a speech codec enabled to code coding speech data at varying speech rates, the transmission power is set in a power controlstate in response to a current signal quality measure and in a rate control state wherein speech transmission is controlled by switching the speech rate in response to the signalqualitymeasure and the transmission power is kept essentially constant Using the method will prevent power control based on the signal quality such as the SIR target when instead it would be better to reduce the used transport block size, i.e. reduce the speech codec rate. As a result of the improved use of radio resources, the voice capacity of a cellular system can be increased, while maintaining speech quality.
Patent•
13 Aug 2002
TL;DR: In this article, a method for supporting an effective sound using an EVRC vocoder in a Noraebang(karaoke) service through a cellular phone and a system therefor are provided to support the effective sound and have a chorus effect using only a software without adding a certain device to the cellular phone.
Abstract: PURPOSE: A method for supporting an effective sound using an EVRC vocoder in a Noraebang(karaoke) service through a cellular phone and a system therefor are provided to support the effective sound using the EVRC vocoder and have a chorus effect using only a software without adding a certain device to the cellular phone in the Noraebang service through the cellular phone. CONSTITUTION: A user connects a wireless Internet service to a server of a mobile communication company connected to a CP(Contents Provider) server in which Noraebang contents are stored using a cellular phone. The user selects a Noraebang service. The user selects the Noraebang contents for being downloaded in the cellular phone. The user receives the Noraebang contents from the CP server. The user executes the downloaded Noraebang contents by a program through the cellular phone.
07 Apr 1986
TL;DR: A 7 kHz-band speech CODEC using an advanced digital signal processor VLSI, "DSSP-1", is developed and arithmetic word-length, arithmetic operation speed, and memory capacity required for this C ODEC is evaluated.
Abstract: A 7 kHz-band speech CODEC using an advanced digital signal processor is developed. The coding algorithm for this CODEC requires greater processing power due to its complexity and high sampling rate. A high-performance digital signal processor VLSI, "DSSP-1", is applied to this CODEC. Arithmetic word-length, arithmetic operation speed, and memory capacity required for this CODEC is evaluated. DSSP-1 can satisfy these requirements; this CODEC has been built with two DSSP-1 chips and several memory chips.
04 Sep 2000
TL;DR: This paper discusses the design and implementation of a low bit rate codec that has a low delay and greater compression, even though the techniques used are simpler and is suitable for applications like video conferencing, mobile communications etc.
Abstract: This paper discusses the design and implementation of a low bit rate codec along with its performance at different bit rates. The International Telecommunications Union's G.728 CELP speech coder is specifically designed for low coding delay and toll quality speech at a rate of 16kbps. Here, we present the design of a CELP(Code Excited Linear Prediction) algorithm similar to the above coder, but can compress speech up to rates like 6.4kbps(as in the G.723.1 standard). This codec shares the advantages of both the above standards; it has a low delay (up to 1.25ms) and greater compression, even though the techniques used are simpler. This advantage makes this coder suitable for applications like video conferencing, mobile communications etc.