在 iOS 上应用带通滤波器
我正在开发一个应用程序,我需要它用 iphone/ipad 上的内置麦克风分析传入频率。我知道我需要使用 FFT,并且我找到了一个可以帮助我的框架。我唯一关心的是是否有包含带通滤波的代码或框架?欢迎提出建议。
编辑 原谅我的无知。我之前发布过文章,当我发现带通既低又低时,我只想使用带通方程。高通滤波器。我仍然欢迎提出建议。
I am developing an application where I need it to analyze the incoming frequency with the built-in microphone on the iphone/ipad. I know that I need to use FFT and I have found a framework that can help me on that. My only concern was is there is a code or framework that includes Band-Pass filtering? Suggestions are welcome.
EDIT
Pardon my ignorance. I previously posted that I wanted to use just a Band-Pass equation, when I found out that Band-pass is both Low & High Pass filters. I still welcome suggestions.
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您始终可以使用双二阶滤波器自己完成此操作。
这是一个很棒的文档,解释了它们的工作原理以及创建带通滤波器需要插入哪些系数: http://musicweb.ucsd.edu/~tre/biquad.pdf
You can always do this yourself using a biquad filter.
Here's a great document explaining how they work and what coefficients you need to plug in to create a bandpass filter: http://musicweb.ucsd.edu/~tre/biquad.pdf
在 iOS 4.x 上,有用于 FFT 和卷积的内置 Accelerate vDSP 框架。但除非您想在 FFT 或卷积例程之上构建,否则没有任何内置功能可用于带通滤波。使用 FFT 进行重叠添加/保存的快速卷积滤波可能非常高效,具体取决于您的滤波器内核要求和信号长度。
On iOS 4.x, there is the built-in Accelerate vDSP framework for FFT and convolution. But unless you want to build on top of the FFT or convolution routines, there is nothing built-in for band-pass filtering. Fast convolution filtering using an FFT for overlap add/save can be very efficient, depending on your filter kernel requirements and the signal length.