生成DTMF音不起作用-应用程序崩溃！ [英] Generating a DTMF tone doesn't work - application crashes!

问题描述

我想生成自定义的DTMF音并在iPhone上播放. 为了做到这一点，我创建并分配了带有自定义音调(ptr)的内存缓冲区. 现在，我想创建一个使用内存缓冲区初始化的NSData对象，然后使用initWithData:error:实例方法将其传递给AVAudioPlayer.

I want to generate a custom DTMF tone and play it on the iPhone. In order to do so, I have created and allocated a memory buffer with a custom tone (ptr). Now I want to create a NSData object, initialized with the memory buffer, and pass it to AVAudioPlayer using initWithData:error: instance method.

我编写了以下代码，但是当我运行应用程序时，它崩溃了.

I wrote the following code, but when I run my application, it crashes.

#import "AudioPlayerViewController.h"
#include <stdlib.h>
#include <math.h>
#define SIZE 10
#define LENGTH 65535
const int PLAYBACKFREQ = 44100;
const float PI2 = 3.14159265359f * 2;
const int freq1 = 697;
const int freq2 = 1209;



@implementation AudioPlayerViewController

@synthesize playButton, stopButton;

- (void)viewDidLoad {
    [super viewDidLoad];
 // Allocate space for an array with ten elements of type int.
int *ptr = malloc(SIZE * sizeof(int));
if (ptr == NULL) NSLog(@"Error: Memory buffer could not be allocated.");
else NSLog(@"Allocation succeeded.");

 // The formula for the tone, the content of the buffer.
for(int i=0; i<SIZE; i++) ptr[i] = (sin(i*(PI2*(PLAYBACKFREQ/freq1))) + sin(i*    (PI2*(PLAYBACKFREQ/freq2)))) * 16383;
NSData *myData = [[NSData alloc] initWithBytesNoCopy:ptr length:SIZE];
free(ptr);
ptr = NULL;
audioPlayer = [[AVAudioPlayer alloc] initWithData:myData error:&error];
audioPlayer.numberOfLoops = -1;
}
-(IBAction) playAudio: (id) sender {
    if (audioPlayer == nil) NSLog([error description]);             
    else [audioPlayer play];
}
-(IBAction) stopAudio: (id) sender { [audioPlayer stop]; }

- (void)dealloc {
    [audioPlayer release];
    [myData release];
    [super dealloc];
}

@end

在文档中，方法initWithBytesNoCopy的描述为:

In the documentation, the description of method initWithBytesNoCopy reads:

包含新对象数据的缓冲区.字节必须指向使用malloc分配的内存块."

"A buffer containing data for the new object. bytes must point to a memory block allocated with malloc."

所以我已经做到了，但是没用.

So I have already done this, but it doesn't work.

任何帮助将不胜感激！

预先感谢

Sagiftw

推荐答案

您正在按SIZE进行分配，但传入LENGTH作为长度.您已将SIZE定义为"10"，并将LENGTH定义为一个巨大的数字.难怪它会在您分配的区域末尾消失！

You're mallocing by SIZE but passing in LENGTH as the length. You've defined SIZE as "10" and LENGTH as a huge number. It's no wonder it goes way mast the end of the region you malloced!

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