#SounDoer# Oculus 音频团队软件工程师 Pete Stirling:Ambisonics 与 Binaural 声音技术科普

@SounDoer:来自 VRDC 的视频,Oculus 音频团队软件工程师 Pete Stirling 对于 Ambisonics 和 Binaural 两种用于 VR Audio 的声音技术科普,以及评测对比。
 

GDC Vault – Evaluating Binaural and Ambisonic Audio Capture and Playback
This session provides a comparison of binaural and ambisonic audio in the context of 360 video – covering multiple aspects including the method of capture, storage and transmission, and technical limitations. On the capture side: a look at the required hardware and the cost of equipment, workflow, and audio post-processing. For storage and transmission: a look at 3D audio compression considerations and compatible video container formats. From a technical perspective: a look at qualitative differences such as artifacts when blending binarual, and the spatial resolution of 1st-order ambisonics.
 
摘要:
  1. Pete Stirling,Oculus 音频团队软件工程师,Talk 内容是有关适用于线性影视媒体的 Ambisonic 和 Binaural 声音技术;
  2. Conventional Audio 常规听音方式:Speaker Based、Front Focused、Uncontrolled Listening Conditions。
  3. Binaural Audio: Microphones placed in ears, Playback in headphones.
    双耳音频,类似于3D电影使用双摄像机拍摄。
  4. Binaural in VR:录制四个方向的 Binaural 声音信号;水平转动定位较好,其他方向定位差。
  5. Ambisonics: 3D Sound Field; Independent of playback configuration; Channels represent directional sound pressure.
    Ambisonics,类似于光场相机的概念。
  6. Ambisonic B-Format 简介。
  7. Ambisonic 录制:四个话筒振膜;A-Format,Raw 4 Channels Capture;A-Format is converted to B-Format.
  8. VR 让 Binaural 和 Ambisonics 这两个老技术重焕新生。
  9. Ambisonics in VR:需要 HRTF 来进行 Spatialize;支持全方向的 Rotation,X-Pitch、Y-Yaw、Z-Roll。
  10. Ambisonics 的一大短处是 Spatial Resolution;改进:Higher Order Ambisonics 介绍。
  11. 对比:Ambisonics,CoreSound Tetramic / Quad-Binaural,3Dio FreeSpace Omni。
  12. Spatialization Accuracy 定位精度
    Quad-Binaural, only yaw rotation, dummy head spatial cues, phase cancellation
    Ambisonics, 1st order has low spatial resolution
  13. Environmental Reflections 空间环境
    Live recording captures reflections, Reinforces visuals, Enhanced sense of presence.
  14. Audio Quality Comparison 音频质量
    Binaural housing causes coloration,声染较多
    Ambisonic has flat frequency response,频响好,利于后期处理
  15. 产品对比
    Quad-Binaural: 3Dio FreeSpace Omni / Pro
    Ambisonics: Brahama, CoreSound TetraMic, TSL SoundField
  16. Delivery:MP4、VPx 格式支持 Multichannel 音频格式
  17. Ambisonics 有一个特点是 Spatialization 时采用的 HRTF 可以个性化调整。
  18. Reflections,有关 Impulse Response 在 Ambisonics 中运用的可能性。
  19. 讨论通过后期制作构建空间声景并导出 Binaural / Ambisonics 格式进行回放的尝试。
 
 
SounDoer – Focus On Sound Design
@SounDoer 编译,若有错误还望不吝指教。转载烦请告知并注明出处。