Reduced Complexity Tree Coding of Speech in the Presence of Background Impairments

在存在背景损伤的情况下降低语音的复杂性树编码

• 批准号: 9627610
• 负责人: Jerry Gibson
• 金额: $ 24.57万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 1999-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9627610&HistoricalAwards=false
• 关键词: Reduced; Complexity; Tree; Coding; Speech

Extraordinary advances in speech coding have been achieved in the past few years, with the ITU and digital cellular industries producing voice coding standards for telephony and videoconferencing with performance perhaps unimaginable even ten years ago. At rates below 12 kbits/s, however, these coders are sometimes criticized for their implementation complexity and for their difficulty in coding speech in the presence of extraneous background impairments. The complexity issue is omnipresent, but becomes increasingly important in the mobile communications environment, both in digital cellular and emerging personal communications systems, where battery power is a dominating issue. Furthermore, there are many applications being developed and proposed for packet-switched videoconferencing at various rates, where it is desirable to have voice coders implemented either wholly in software on standard platforms (Macs, PCs, Sparcs) or whose implementations do not usurp large portions of the capabilities of a DSP chip. Being able to code speech in the presence of background impairments has always been of interest, but has recently moved to the fore because of the mobile environments encountered in digital cellular mobile radio and evolving personal communications systems. Desktop applications also present a challenge for coding with background impairments, since hands-free interaction is critical and thus even some relatively quiet office environments do not have the handset to aid in rejecting the background noise. The challenge is therefore to achieve communications quality speech at 8 kbits/s with medium-to-low complexity for a variety of implementation approaches without changing background impairments into annoying artifacts. This research approaches this problem by starting with a low delay waveform following coder, called a tree coder, removing the low delay requirement and employing frequency domain based variable rate techniques, forward adaptation ideas, code tr ee adaptivity innovations, and improved perceptual weighting to reduce implementation complexity while retaining reconstructed speech quality.

在过去的几年中，已经实现了语音编码的非凡进步，ITU和数字蜂窝行业为电话和视频会议制作了语音编码标准，甚至十年前的性能也可能难以想象。 但是，以低于12 kbits/s的速度，这些编码人员有时因其实施复杂性以及在存在外部背景障碍的情况下进行编码的难度而受到批评。 复杂性问题是无所不在的，但是在移动通信环境中，在数字蜂窝和新兴的个人通信系统中，电池电量是一个主导问题，变得越来越重要。此外，有许多应用程序正在开发和提出，以各种速度进行数据包开关的视频协调，可以在标准平台（MAC，PC，SPARCS）上完全实施语音编码器，或者其实现的功能并没有篡夺DSP芯片功能的大部分功能。 能够在背景障碍的存在下进行编码的语音一直很感兴趣，但是由于数字蜂窝移动无线电和不断发展的个人通信系统中遇到的移动环境，最近已移动到临时。 桌面应用程序还提出了针对背景障碍的编码的挑战，因为免提互动至关重要，因此即使是一些相对安静的办公环境也没有手机来帮助拒绝背景噪声。 因此，面临的挑战是在8 kbits/s的情况下以中低的复杂性在各种实施方法中实现质量质量语音，而不将背景障碍变成令人讨厌的工件。这项研究通过从编码器的低延迟波形开始，称为树编码器，删除低延迟需求并采用基于频域的可变速率技术，向前的适应思想，代码TR EE适应性创新以及改善感知权重以减少实施复杂性，同时恢复重建语音质量，从而解决了这个问题。