iPhone - AVAudioPlayer - 将分贝级别转换为百分比 [英] iPhone - AVAudioPlayer - convert decibel level into percent

问题描述

我想更新使用AudioQueue播放音频文件的现有iPhone应用程序。级别（peakPowerForChannel，averagePowerForChannel）是0.0f到1.0f的线性形式。

I like to update an existing iPhone application which is using AudioQueue for playing audio files. The levels (peakPowerForChannel, averagePowerForChannel) were linear form 0.0f to 1.0f.

现在我喜欢使用更简单的AVAudioPlayer类，工作正常，唯一的问题是现在以分贝为单位的水平，而不是从-120.0f到0.0f的线性。

Now I like to use the simpler class AVAudioPlayer which works fine, the only issue is that the levels which are now in decibel, not linear from -120.0f to 0.0f.

有没有人将公式转换回0.0f和1.0f之间的线性值？

Has anyone a formula to convert it back to the linear values between 0.0f and 1.0f?

谢谢

Tom

推荐答案

几个Apple示例使用以下公式将分贝转换为线性范围（从0.0到1.0）：

Several Apple examples use the following formula to convert the decibels into a linear range (from 0.0 to 1.0):

double percentage = pow (10, (0.05 * power));

其中 power 是你得到的价值各种电平表方法或功能之一，例如AVAudioPlayer的 averagePowerForChannel：

where power is the value you get from one of the various level meter methods or functions, such as AVAudioPlayer's averagePowerForChannel:

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