共查询到20条相似文献,搜索用时 46 毫秒
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本文在简要说明MPEG音频编码标准发展史和音频编码的基础之后,重点介绍了MPEG-4音频编码标准,包括:MPEG-4音频编码标准概要;MPEG-4的“型”与“层”;自然语言信号的编码;自然声音信号的编码;MPEG-4音频标准的特殊功能;合成语言信号的编码;合成声音信号的编码;音频景象的描述;现在和将来的应用。最后展望了音频编码方法未来的发展趋势。 相似文献
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曾制定出MPEG-1和MPEG-2视音频压缩标准的运动图像专家组(MPEG)目前正在发展最新的MPEG-4标准,其目标是提供未来的交互式多媒体应用.MPEG-4将制定出与以往不同的、具有高度灵活性和可扩展性的未来新一代国际标准.在音频标准的制定方面,比较以前的音频编码标准,MPEG-4增加了许多新的关于合成内容及场景描述等领域的工作,增加了诸如可分级性、音调变化、可编辑性及延迟等新功能.MPEG-4将以前发展良好但相互分离的高质量音频编码、计算机音乐及合成语音等第一次合成并在一起,在诸多领域内给予高度的灵活性. 相似文献
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介绍了MPEG-4音频可分级无损压缩编码方案中无损增强层的编码。对无损增强层中的残差映射、比特平面编码、基于上下文的算术编码、低能量编码等技术细节进行了深入讨论和分析。最后将MPEG-4SLS与Monkey’s Audio编码方案进行了比较,以此来说明MPEG-4SLS优异的压缩性能。 相似文献
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视频和音频编码完成后,需要通过传送部分把数据送给解码器。MPEG-2和MPEG-4在数据传送方面有些相似性: 相似文献
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Lossless audio compression is likely to play an important part in music distribution over the Internet, DVD audio, digital audio archiving, and mixing. The article is a survey and a classification of the current state-of-the-art lossless audio compression algorithms. This study finds that lossless audio coders have reached a limit in what can be achieved for lossless compression of audio. It also describes a new lossless audio coder called AudioPak, which low algorithmic complexity and performs well or even better than most of the lossless audio coders that have been described in the literature 相似文献
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最近提出的MPEG无损音频编码标准(MPEG-4音频SLS(scalable to Lossless编码技术)提供了一种统一的语音模式,这种语音模式可以将有损语音编码,无损语音编码以及粒度可伸缩语音编码的功能结合在 一个框架中.我们提出了两种提高SLS编码效率的方法,即基于上下关系的算术编码方法和低能量模式编码方法.这两种方法同当前的SLS框架搭配在一起运行,可以保持它的好的特征如:粒度可伸缩性,同时可以成功地改善它的无损压缩性能. 相似文献
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在语音信号处理的许多应用中,采用了无损音频压缩的方法.回顾了MPEG-4音频技术的现状,MPEG-4 ALS(Audio Lossless Coding)标准化过程以及编解码技术.详细介绍了编码器中的线性预测、量化、熵编码等模块,展望了MPEG-4 ALS的应用前景. 相似文献
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《Signal Processing, IEEE Transactions on》2006,54(8):3064-3077
In this paper, we present a scalable approach to lossless watermarking for audio signals. The proposed watermarking framework is built on a recently standardized two-layer scalable audio coder advanced audio zip (AAZ) . By embedding watermarks in both the core layer and enhancement layer bitstreams in a special way, the watermark distortion in either layer is compensated by the watermark in the opposite layer. The proposed spread-spectrum-based solution overcomes both the problem of introducing noninvertible distortions in lossy watermark approaches and the problem of nonadaptive embedding in lossless watermarking approaches. Theoretic analysis and experiment results further confirm the validity of the proposed framework in terms of payload, robustness, data expansion property, and perceptual quality. 相似文献
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阐述了电视系统中的音频嵌入技术,音视频信号标准,嵌入格式和加解嵌在电视系统中的应用。通过使用音频嵌入技术,大大降低了电视信号的传输成本,提高了音频信号的传输质量,解决了音视频信号传输中不同步的问题,实现了音视频无损耗传输,提高了电视节目的质量。 相似文献
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FLAC编码可实现对音频数据的无损压缩。针对目前尚未出现硬件解码芯片的情况,介绍了基于ARM嵌入式的解码方案。系统可实现通过USB接口读取FLAC数据,解码后的PCM数据流通过IIS总线输出,整个方案可应用于高端音频流播放设备。 相似文献
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Jin Li 《Signal Processing, IEEE Transactions on》2005,53(5):1870-1880
A reversible transform converts an integer input to an integer output, while retaining the ability to reconstruct the exact input from the output sequence. It is one of the key components for lossless and progressive-to-lossless audio codecs. In this work, we investigate the desired characteristics of a high-performance reversible transform. Specifically, we show that the smaller the quantization noise of the reversible modified discrete cosine transform (RMDCT), the better the compression performance of the lossless and progressive-to-lossless codec that utilizes the transform. Armed with this knowledge, we develop a number of RMDCT solutions. The first RMDCT solution is implemented by turning every rotation module of a float MDCT (FMDCT) into a reversible rotation, which uses multiple factorizations to further reduce the quantization noise. The second and third solutions use the matrix lifting to implement a reversible fast Fourier transform (FFT) and a reversible fractional-shifted FFT, respectively, which are further combined with the reversible rotations to form the RMDCT. With the matrix lifting, we can design the RMDCT that has less quantization noise and can still be computed efficiently. A progressive-to-lossless embedded audio codec (PLEAC) employing the RMDCT is implemented with superior results for both lossless and lossy audio compression. 相似文献