| 题名 | BCC算法的实现及基于NDFT的参数估计改进 |
| 作者 | 仇波 |
| 学位类别 | 博士 |
| 答辩日期 | 2008-05-27 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | Binaural Cue Coding (BCC) 声道间声级差 声道间时间差 等效矩形带宽 非均匀离散傅立叶变换 |
| 其他题名 | Implementation and NDFT-based Improvement of Binaural Cue Coding |
| 学位专业 | 信号与信息处理 |
| 中文摘要 | 双耳信息编码（Binaural Cue Coding，BCC）是近几年兴起的一种多声道音频编解码技术，通过将多声道的音频信号缩混为单声道的和信号，同时提取声道之间与人的空间听觉相关的小数据量的边信息，能实现传输和存储数据量的压缩。BCC可以利用现有的传统的编解码算法实现底层压缩，更进一步的降低数据量。BCC是有损压缩算法，无法实现音质还原的完全透明。对于某些双声道环绕声信号，BCC解码后的音质还存在某些缺陷。 本文以双声道的3D音频信号为例，根据BCC算法的基本流程原理，实现了基于MP3底层编码的BCC算法。在此基础之上，本文通过几个简单的音频信号的编解码效果对比，指出算法中可能存在的一些局限性。对此，本文引入了非均匀离散傅立叶变换（Nonuniform Discrete Fourier Transform，NDFT），提出了一种从时域到心理声学频域的变换方法，提高了低频段参数估计的谱线数目，适当降低了高频段参数估计的谱线数目，从而尝试了对BCC算法的改进。 为了评价改进后算法的效果，本文根据ITU的相关标准，设计了相应的主观评价方法，并组织了17个人的测听实验。在5分制的评价结果中，改进的BCC算法的音质评价平均得分为4.43分，声像宽度平均得分为3.99分，比传统算法的4.25分和3.59分都要高。这表明，改进算法较传统算法无论是整体音质还是声像宽度还原都有了一定的改善。另外，结果也表明，基于MP3底层编码的BCC算法较MP3算法具有不少的优越性。 本文最后总结本文的工作，分析了工作中遗留的种种问题，对后续工作提出了展望性的意见。 |
| 英文摘要 | Binaural Cue Coding (BCC) is an efficient technique for spatial audio rendering by using the side information such as inter-channel level difference (ICLD), inter-channel time difference (ICTD), and inter-channel correlation (ICC). The sum signal, which multi-channel signals are down-mixed to, can be compressed by the state-of-the-art codec in order to decrease the bitrate much more. BCC is a kind of lossy coding. It is not so satisfactory to compress some stereo surround signals. In the background of 3D audio signals, the BCC algorithm with the bottom layer of MP3 is implemented. Comparing several basic coded signals, it is found that there might be some limitations in the algorithm. In consequence, NDFT is introduced and a transform from time domain to psychoacoustic-frequency domain, which increases frequency bins in low frequency bands and decreases those in higher bands in a proper way, is proposed to improve BCC. Based on ITU’s standard recommendations, a corresponding subjective assessment is designed, and the listening test with 17 subjects is organized subsequently. From results of the 5-point scale scores, the improved BCC algorithm obtains 4.43 averagely in audio quality and 3.99 in auditory image width. Both are respectively higher than 3.99 and 3.59 of the original BCC algorithm, which indicates that the improved algorithm performs better than the original algorithm whether in audio quality or in auditory image width. Moreover, results also show much more advantage of MP3-based BCC algorithm than MP3. Finally, a conclusion is made, the existing problems of the work are analyzed and some prospective advices for the future research are given in the last part of this thesis. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 65 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.59.140/handle/311008/390]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 仇波. BCC算法的实现及基于NDFT的参数估计改进[D]. 声学研究所. 中国科学院声学研究所. 2008. |
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