iOS SoundTouch框架BPM检测示例 [英] iOS SoundTouch framework BPM Detection example

问题描述

我在网上搜索过，无法找到有关如何使用 SoundTouch库的教程用于节拍检测。

I have searched all over the web and cannot find a tutorial on how to use the SoundTouch library for beat detection.

（注意：在此之前我没有C ++经验。我知道C，Objective-C和Java。所以我可能搞砸了其中一些，但是编译。）

(Note: I have no C++ experience prior to this. I do know C, Objective-C, and Java. So I could have messed some of this up, but it compiles.)

我添加了框架到我的项目并设法获得以下编译：

I added the framework to my project and managed to get the following to compile:

NSString *path = [[NSBundle mainBundle] pathForResource:@"song" ofType:@"wav"];

NSData *data = [NSData dataWithContentsOfFile:path];

player =[[AVAudioPlayer alloc] initWithData:data error:NULL];

player.volume = 1.0;

player.delegate = self;

[player prepareToPlay];
[player play];

NSUInteger len = [player.data length]; // Get the length of the data

soundtouch::SAMPLETYPE sampleBuffer[len]; // Create buffer array

[player.data getBytes:sampleBuffer length:len]; // Copy the bytes into the buffer

soundtouch::BPMDetect *BPM = new soundtouch::BPMDetect(player.numberOfChannels, [[player.settings valueForKey:@"AVSampleRateKey"] longValue]); // This is working (tested)

BPM->inputSamples(sampleBuffer, len); // Send the samples to the BPM class

NSLog(@"Beats Per Minute = %f", BPM->getBpm()); // Print out the BPM - currently returns 0.00 for errors per documentation

inputSamples（* samples，numSamples）歌曲字节信息让我困惑。

The inputSamples(*samples, numSamples) song byte information confuses me.

如何从歌曲文件中获取这些信息？

How do I get these pieces of information from a song file?

我尝试使用 memcpy（）但它似乎无法正常工作。

I tried using memcpy() but it doesn't seem to be working.

有人有什么想法吗？

推荐答案

经过数小时的调试和阅读有限的文档在网上，我修改了一些东西，然后绊倒了：你需要在 numberOfChannels 中将 numSamples 划分为 inputSamples（） function。

After hours and hours of debugging and reading the limited documentation on the web, I modified a few things before stumbling upon this: You need to divide numSamples by numberOfChannels in the inputSamples() function.

我的最终代码是这样的：

My final code is like so:

NSString *path = [[NSBundle mainBundle] pathForResource:@"song" ofType:@"wav"];

NSData *data = [NSData dataWithContentsOfFile:path];

player =[[AVAudioPlayer alloc] initWithData:data error:NULL];

player.volume = 1.0;    // optional to play music

player.delegate = self;

[player prepareToPlay]; // optional to play music
[player play];          // optional to play music

NSUInteger len = [player.data length];

soundtouch::SAMPLETYPE sampleBuffer[len];

[player.data getBytes:sampleBuffer length:len];

soundtouch::BPMDetect BPM(player.numberOfChannels, [[player.settings valueForKey:@"AVSampleRateKey"] longValue]);

BPM.inputSamples(sampleBuffer, len/player.numberOfChannels);

NSLog(@"Beats Per Minute = %f", BPM.getBpm());

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