Adaptive Multi-Rate audio codec

About: Adaptive Multi-Rate audio codec is a research topic. Over the lifetime, 1467 publications have been published within this topic receiving 19736 citations. The topic is also known as: AMR & Adaptive Multi-Rate.

Fullband conversational codec: What testing methodology?

Abstract: In ITU-T Study Group 12, the ITU-T lead study group on quality of service and performance, most of the activities have mainly focused until now on Narrowband and Wideband speech codec performance evaluation. As ITU-T Study Group 16 (that has a mandate for studies on media coding), is working on codecs with wider audio bandwidth, ITU-T SG12 has extended its scope to study quality assessment methodologies appropriate for wider bandwidths. After a presentation of ITU-T speech and audio codec standardization process and an overview of the audio quality testing methodologies, this paper describes the ITU-T G.722.1 Fullband qualification exercise and the adopted testing methodology as well as the following characterization phase and its related methodology.

A new hybrid non-uniform coding with low bit rates for sound signal in near field communication

Abstract: In speech or audio processing, coding may be define as a digital representation of signal that provides efficient storage, transmission, recovery, and perceptually faithful reconstruction of the original signal In the coding methods, the waveform coding method can maintain the high quality and intelligibility, but the major drawback of this method is large amount of data required Therefore, we proposed a waveform coding method using the non-uniform sampling and variables low pass filter of speech or audio signals Simulation results show that this algorithm is robust in noisy environments

Low bit rate videophone codec for ISDN applications

Abstract: This article presents the performance results of a low-bit rate image codec for videophone and B /2 B channel ISDN applications. The codec at the encoder skips two frames over three images and encodes every one image over three using DCT-Huffman coding and sends together with the motion vectors computed over overlapped blocks. At the receiver, the missing frames are constructed by linear interpolation using coded frames and respective motion vectors. The effectiveness of the codec is evaluated by employing two video sequences as input. The resulting video sequences indicate that for videophone applications, an acceptable quality of image is obtained. Therefore, this codec can be a good candidate for a videophone in ISDN network. Finally, the implementation considerations of this codec are also given.

Bit-rate control algorithm on video packet coding and its characteristics

Abstract: A bit-rate control method based on a hybrid coding algorithm is proposed for packet video coding. Three types of bit-rate control modes, the constant bit-rate mode, the average bit-rate control mode and the free bit-rate mode, are investigated. According to the opinion test the latter two modes have an advantage in video quality over the constant bit-rate mode. A teleconference terminal, which includes this video codec, audio codec and packet adaptor, is implemented in actual hardware on High-speed Packet Switching system. On this system, video information are transmitted in UI frame (a packet format in X.25 protocol) at 64 K ∼ 800 Kbit/s.

Wyner-Ziv Video Coding with Part Intracoding

Abstract: In Wyner-Ziv video coding, efficient compression is achieved by exploiting source statistics at the decoder only, which is radically different from conventional video coding. Prior works on this topic generally use channel coding to implement Slepian-Wolf codec. However, the correlation between some bit planes of source and that of side information may be very weak. At that time, the coding performance of Slepian-Wolf codec should be lower than that of intracoding codec. If we can divide the video data into strongly correlative data encoded by Slepian-Wolf codec and weakly correlative data encoded by Intracoding codec, the coding performance of video codec would be improved. In this paper, we proposed a novel distributed video coding scheme with part intracoding. Simulation results show that the proposed scheme can achieve better compression efficiency while keeping the simple encoding property.