Spatial transformations for the enhancement of Ambisonic recordings
Spatial transformations for the enhancement of Ambisonic recordings
复制标题
用于增强 Ambisonic 录音的空间变换
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
F. Zotter
中科院分区：
文献类型：
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作者：
M. Kronlachner;F. Zotter
用于圆形或球形环绕回放设施的空间音频制作通常使用高保真度立体声，因为它提供了平移的平滑度，并且因为它的经典和新的主麦克风阵列技术。与环绕声中基于声道的标准相比，Ambisonics理想地提供了关于收听区域周围的扬声器设置的灵活性。设计良好的解码器应该产生一个空间的角度，在很大程度上是独立的这种设置。随着能够记录更高阶高保真度立体声响复制的麦克风的日益增加的可用性，高保真度立体声响复制域中的各种变换对于后期制作和回放期间的增强是期望的和必要的。源位置或其响度水平的改变可以通过在角域中应用的变换来容易地完成，其幼稚但不切实际的实现将是与解码器中指定的那些不同地设置回放扬声器。幸运的是，相应的变换总是可以作为高保真度立体声信号域中的矩阵运算来执行，然而，目前还没有很好地描述。特别是，这样的改变仅对一阶高保真度立体声响复制有很好的描述，而我们缺乏对更高阶高保真度立体声响复制的系统描述。这项工作提出了现成的实现方式，用于高阶高保真度立体声响复制的记录视角和方向响度修改的翘曲。此外，在过去，环绕声母版制作只能通过人耳来完成，因此本文介绍了一种用于监测环绕声录音的方向性响度水平的测量工具。
Spatial audio productions for circular or spherical surround playback facilities often use Ambisonics because of the smoothness it offers for panning and because of its classical and new main microphone array technology. In contrast to channel-based standards in surround sound, Ambisonics ideally offers flexibility regarding the loudspeaker setup around the listening area. Well-designed decoders should yield a spatial perspective that is largely independent of this setup. With the increasing availability of microphones capable of recording higher order Ambisonics, various transformations in the Ambisonic domain are desirable and necessary for enhancements during post production and playback. Alteration of source positions or their loudness levels can easily be done by transformations applied in the angular domain, of which a naive but impractical realisation would be to set up the playback loudspeakers differently than those specified in the decoder. Fortunately, corresponding transformations can always be performed as matrix operation in the Ambisonic signal domain, which, however, is currently not described well. In particular, such alterations are only well-described for first-order Ambisonics, while we lack systematic descriptions for the higher Ambisonic orders. This work presents ready-to-use implementations for the warping of the recording perspective and directional loudness modification of higher-order Ambisonics. What is more, Ambisonic mastering has only been done by ear in the past, wherefore this paper introduces a metering tool for monitoring the directional loudness levels of Ambisonic recordings.