标题: | 多重正弦激励的宽频音讯编码 Multi-Sinusoidal Excitation Model in Audio Coding |
作者: | 王礼玮 Li-Wei Wang 张文辉 Dr. Wen-Whei Chang 电信工程研究所 |
关键字: | 音讯编码;遮蔽效应;多重正弦激发;码书激发线性预估编码;;Audio Coding;Masking Effect;Multi-Sinusoids Excitation; Code-Excited LPC; |
公开日期: | 1992 |
摘要: | 目前在高品质音讯编码的研究皆把焦点放在不是次频带就是转换编码上, 他们皆使用遮蔽效应于动态位元分配中,形成了听不到的杂讯频谱。然而 ,这些频域编码的方式皆耗费了大量的计算而且多余的讯息需要进一步消 除。在另一方面,时域编码若结合一个适当的激发结构,仍有潜力在重现 时达到不失真。在这篇论文中,我们提出一个由不同振幅的正弦函数组成 的多重正弦激发架构,而不是像码书激发线性预估编码的白色杂讯架构。 效能结果显示不仅是在传统的失真量测如信号杂讯比和分段信号杂讯比, 亦在最新提出的客观品质量测如一般化的巴克 (bark) 频谱失真都有显着 的改善。更进一步地,这多重正弦激发架构亦简化了90倍的计算量。 Current research on high-quality audio coding focuses on either subband or transform coding whereby the masking effect is exploited in dynamic bit allocation to result in an inaudible noise spectrum. However, the frequency-domain coding approaches consume heavy computations and the redundancy remains to be removed further. On the other hand, time-domain coders have the potential to achieve transparent reproduction by incorporating an appropriate excitation structure. In this thesis, we propose a multi-sinusoids excitation structure which consists of the sum of gain-scaled sinusoidal functions, rather than the white noise as in Code-Excited LPC (CELP). The performance results show significant improvement not only in the conventional distortion measure such as SNR and segSNR, but also in the newly proposed objective quality measure called generalized bark spectral distortion (GBSD). Further more, a multi- sinusoids excitation structure also simplifies the computation load in about 90 times. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT810436026 http://hdl.handle.net/11536/57009 |
显示于类别: | Thesis |