什么音频延迟
音频延迟，简单理解就是音频从输入系统到输出系统的时间差。
可以有很多种表现形式，比如在网络通话场景，说话方的声音到达接听方，经过的时间；或者在玩游戏的时候，手指按下了枪的扳机，到你听到枪声。
在不同的系统上，在软件、硬件设备上，都会出现，是一个通用的现象。从某种意义上来说，存在且不可避免。
因为所谓的实时性通常都不是指零误差，零延时，而是针对你的使用场景，满足一定期望以内的时延即可以称之为实时。
参考：https://help.ableton.com/hc/en-us/articles/360010545559-How-Latency-Works
Latency refers to a short period of delay between when a signal enters a system, and when it emerges from it.
Latency cannot be avoided, but it can be understood!
音频延迟怎么产生的
音频延迟的产生，在数字音频来看，就是两个原因：信号处理，音频buffer。
In digital audio, latency is introduced by signal conversion and audio buffers within the signal path.
How-Latency-Works
信号处理
包含ADC、DAC转换，这是数字音频的入口和出口。
音频buffer
在硬件或者软件通路上，用于临时存储音频数据的区域，在通路中从上一个节点传递到下一个节点。
哪里会发生音频延迟
- The audio interface
- The audio interface driver
- The operating system (which may require additional time to process and mix streams from other applications before passing it out to the speakers)
- Between the Audio Interface and the DAW
- In the DAW’s signal processing (eg. monitored tracks / native effects / plug-ins / etc.)
音频延迟计算
Buffer Size (number of samples) ÷ Sample Rate (kHz) = Expected Latency (ms).
For example, while running with a Buffer Size of 256 samples and a Sample Rate of 44.1 kHz,
an audio interface will convert the incoming signal with 5.8 milliseconds of expected latency before sending it into Live (256 samples ÷ 44.1 kHz).