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.

Implementation of G.729 Codec Based on Mediastreamer Technology

Abstract: Currently, the mediastreamer2 contains internal support for G.711u, G.711a, speex and gsm. However, it does not contain internal support for the popular G.729, which is known as the best audio codec ever. In this paper, we present the method of how to implement a G.729 codec filter on mediastreamer2. Then, we evaluate the performance of the G.729 filter in our platform. The experimental results show that our implementation of G.729 codec on mediastreamer2 is successful on the whole.

Performance comparison of audio codecs for high-quality color ring-back-tone services over CDMA

Abstract: In this paper, we investigate the use of existing audio codecs for the purpose of a high quality color ring-back- tone service. First of all, we exploit the limitations of the enhanced variable rate codec (EVRC) in a view of music quality because EVRC is a standard speech coder employed in a code division multiple access (CDMA) system. In order to figure it out which current existing audio codec is suitable to deliver music over CDMA or wideband CDMA (W-CDMA), several audio codecs such as two different versions of MPEG AAC and the Enhanced AAC+ codec are reviewed. Next, the music quality of the audio codecs is compared with that of EVRC, where the bit-rates of the audio codecs are set to be around 10 kbit/s because the color ring-back-tone service using one of the audio codecs should be realized by replacing EVRC with it. The quality comparison is performed by an informal listening test as well as an objective quality test. It is shown from the experiments that the audio codecs provide better music quality than EVRC and among them, the Enhance AAC+ codec operated at a bit-rate of 10 kbit/s with a sampling rate of 32 kHz can be considered as a new candidate for the high quality color ring-back-tone service.

Rate Quality Factor Optimization for VP8 Video Codec for Mobile Communication Applications

Abstract: In this paper, mainly, we are proposing a better rate control algorithm optimization technique; it is applying for VP8 video coding for improving the performance and also quality of video codec data for mainly mobile communication applications. Actually, rate control plays an better role in video coding and transmission to provide the best video quality at the receiver end, and our proposed algorithm technique mainly exploits the existing constant quality control, which is governed by a parameter called quality factor (QF) to give a constant bit rates. For this purpose, a new mathematical model called the rate–quality factor(R–Q′) is derived to generate optimum QF for the current coding frame using the bitrates resulting from the encoding of the previous frame in order to meet the target bitrates. The process of calculating the QF is simple, and further calculation is not required for each coded frame. It also provides the rate control solution for both intra-frame-only and inter-frame coding modes. Our all experimental results show that the proposed scheme generates coding bits very close to target bits and provides improved coding efficiency at low bit rates also introducing simple complexity to measure for the video content. So that, in this proposed method considering previous results and comparing with our results then confirm by comprehensive experiments results.. The quality control parameter can be derived from Lagrangian multiplier and hence can be used in any type of encoder that uses RDO. Experimental results have shown that the proposed algorithm can control the bitrates within 1 % of the target bitrates on average, and it has better bitrates regulation over each GOP than the rate control algorithm of H.264. This is an advantage that is crucial in real-time multimedia data streaming in preventing buffer overflow or underflow. Performance of this video data is analyzed using PSNR and bitrates which needs to calculate once this new technique is implemented on specified plat form.

Method for eliminating noises of enhanced variable rate codec of cdma system in weak electromagnetic field

Abstract: PURPOSE: A method is provided to eliminate noises of an EVRC(Enhanced Variable Rate Codec(Coder-Decoder) by outputting unnecessary noises, generated in a weak electromagnetic field of a CDMA(Cord Division Multiple Access) system, as background noises. CONSTITUTION: A method for eliminating noises of an EVRC(Enhanced Variable Rate Codec(Coder-Decoder) in a weak electromagnetic field distinguishes full rates/half rates or 1/8 rates, distinguished through a valid packet right after a previous state when an error packet is inputted. A seed value of a random number generator is converted into a static variable in a process routine of an error frame, corresponding to the distinguished full rates of the half rates. The seed value is set up only in a first sub frame of a first error packet.

A Novel Rate Selection Algorithm for Transcoding CELP-type Codec and SMV

Abstract: In this paper, we propose an efficient rate selection algorithm that can be used to transcode speech encoded by any code excited linear prediction (CELP)-type codec into a format compatible with selectable mode vocoder (SMV) via direct parameter transformation. The proposed algorithm performs rate selection using the CELP parameters. Simulation results show that while maintaining similar overall bit-rate compared to the rate selection algorithm of SMV, the proposed algorithm requires less computational load than that of SMV and does not degrade the quality of the transcoded speech.