AVAudioPlayer变化率引入假象/失真 [英] AVAudioPlayer rate change introduces artifacts/distortion

问题描述

我试图改变一个声音文件通过AVAudioPlayer播放的速度。它的工作原理，但也有显著的工件，特别是当我减慢速度。我很高兴，房价的变化保持相同的间距，但它似乎有麻烦，尤其是音。

I am trying to change the rate of a sound file played through AVAudioPlayer. It works, but there are significant artifacts, especially when I slow down the rate. I'm happy that the rate change maintains the same pitch but it seems to have trouble, especially with sustained notes.

那好像是利率变化的工作pretty很好，直到我已被扳平更高质量的声音，玉米pressed，并掌握​​试了一下。我担心的AVAudioPlayer变化率无法应付更高的质量。

It seemed like the rate change was working pretty well until I tried it with higher quality sounds that had been equalized, compressed, and mastered. I'm concerned that the AVAudioPlayer rate change can't deal with the higher quality.

我使用.wav文件以48kHz的采样率和每个样本16位。

I'm using .wav files with a sample rate of 48kHz and 16 bits per sample.

我也看着ZTX时间伸缩和变调，原名狄拉克LE，但一直没能获得该软件的许可呢。不过，我也尝试加载文件到使用该技术ZTX iPhone应用程序，它有类似的问题。

I've also looked into ZTX Time Stretching and Pitch Shifting, formerly known as Dirac LE, but haven't been able to acquire a license for the software yet. However, I did try loading the files into iPhone apps that use the ZTX technology and it had similar issues.

任何帮助或建议将是AP preciated！

Any help or suggestions would be appreciated!

推荐答案

有在更高的频率越来越接近两每个周期为20 kHz每个周期较少的数据点。减慢音频具有相同的螺距涉及添加更多的数据点，并且不能完全准确，因为该信息是不是在原始present

There are fewer data points per cycle at higher frequencies getting close to two per cycle at 20 khz. Slowing down the audio with the same pitch involves adding more data points and that can't be completely accurate because that information was not present in the original.

进一步改变速度的过程中不改变的节距是一个复杂的操作。越声放缓将推出更多的文物。注意：你还没有说你要什么样的放缓比为90％，50％，10％

Further the process of changing the speed without altering the pitch is a complex operation. The more the sound is slowed the more artifacts that will be introduced. Note: You still have not stated what kind of slowing ration you are going for, 90%, 50%, 10%?

如果减速的量是极端使用更高的采样频率。

If the amount of slowing is extreme use a higher sampling frequency.

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