CAREER: Efficient Audio Compression with Perceptually Embedded Scalability

[01:31 . 15] charles D. creusere新墨西哥州立大学具有感知嵌入式可扩展性的高效音频压缩该项目的重点是开发更适合当前正在开发和部署的集成无线/固定电话通信网络的音频数据压缩格式。这种网络的异构性质要求压缩存储格式，从中可以提取精细的音频保真度层；因此，通信网络上的每个听众都会收到他或她的通信信道所能支持的尽可能多的音频保真度层（即，最好质量的音频再现），所有这些都是从这个单一压缩表示中提取出来的。这种技术的一个明显应用是通过3G蜂窝和蓝牙等即将到来的无线服务提供音乐点播服务。精细分层或“可扩展”的比特流也可用于通过简化速率缓冲控制和错误保护来改善互联网或广播无线信道上的实时音频流。本文的研究重点是开发一种高性能压缩算法，该算法的可扩展性在整个输出保真度范围内针对感知性能进行了优化。目前广泛使用的大多数音频压缩算法——MP3 （MPEG音频层3）、MPEG AAC、杜比数字等——都不支持比特流的可扩展性。在MPEG 2和MPEG 4框架中，使用一种称为位切片算术编码（BSAC）的技术来支持细粒度的可伸缩性。不幸的是，主观测试表明BSAC的可扩展性并没有针对较低比特率下的声音质量进行优化。为了更紧密地将比特分配过程与感知质量联系起来，这里使用了一个非均匀多速率滤波器组，其频率分辨率接近人类听力的关键波段。然后使用矢量和标量技术以最佳的多阶段方式在每个关键波段内进行量化。

0133115Charles D. CreusereNew Mexico State UniversityEfficient Audio Compression with Perceptually Embedded ScalabilityThe focus of this project is to develop compression formats for audio data that are better suited to the integrated wireless/landline communications networks currently being developed and fielded. The heterogeneous nature of such networks demands a compressed storage format from which fine layers of audio fidelity can be extracted; thus, each listener on the communications network receives as many layers of audio fidelity (i.e., the best quality audio reproduction) that his or her communications channel can support, all extracted from this single compressed representation. An obvious application of such technology is music-on-demand over forthcoming wireless services like 3G cellular and Bluetooth. A finely layered or 'scalable' bit stream can also be used to improve the streaming of real-time audio over the Internet or a broadcast wireless channel by simplifying rate buffer control and error protection.The research here concentrates on developing a high-performance compression algorithm whose scalability is optimized for perceptual performance over the entire range of output fidelities. Most of the audio compression algorithms in wide use today-- MP3 (MPEG audio layer 3), MPEG AAC, Dolby Digital, etc.-- do not support bitstream scalability. Within the frameworks of MPEG 2 and MPEG 4, fine-grained scalability is supported using a technique called bit slice arithmetic coding (BSAC). Unfortunately, subjective testing has shown that BSAC's scalability is not optimized for perceived sound quality at lower bitrates. To more closely tie the bit allocation process to the perceived quality, a non-uniform multirate filter bank is used here whose frequency resolution approximates that of the critical bands of human hearing. Quantization within each critical band is then performed in an optimal, multistage manner using both vector and scalar techniques.