[iphone-cocos2d]分享一段Objective-C可调用的游戏中播放音乐(1)

首先需要引入AudioTool 这个framework

 

- (id)initWithPath:(NSString *)path
{
    UInt32        size, maxPacketSize;
    char        *cookie;
    int            i;
    
    if (gThereIsAnActiveTrack)
    {
        NSLog(@"*** WARNING *** GBMusicTrack only plays one track at a time! You must close the previously running track"
              " before you can play another. Requested track was: %@", [path lastPathComponent]);
        return nil;
    }
    //路径不存在的话返回空
    if (path == nil) return nil;
   // 初始化　　
    if(!(self = [super init])) return nil;
    
    // 通过指定的路径打开音乐
    if (noErr != AudioFileOpenURL((CFURLRef)[NSURL fileURLWithPath:path], 0x01, 0, &audioFile))
    {
        NSLog(@"*** Error *** GBMusicTrack - initWithPath: could not open audio file. Path given was: %@", path);
        return nil;
    }
    
    // 得到文件的数据类型
    size = sizeof(dataFormat);
    AudioFileGetProperty(audioFile, kAudioFilePropertyDataFormat, &size, &dataFormat);
    
    // 创建一个新的队列，使用的是指定的特殊数据类型和回调缓存。
    
    AudioQueueNewOutput(&dataFormat, BufferCallback, self, nil, nil, 0, &queue);
    
    // 如果需要的话读取包的大小并且分配所需要的空间
    if (dataFormat.mBytesPerPacket == 0 || dataFormat.mFramesPerPacket == 0)
    {
        // since we didn't get sizes to work with, then this must be VBR data (Variable BitRate), so
        // we'll have to ask Core Audio to give us a conservative estimate of the largest packet we are
        // likely to read with kAudioFilePropertyPacketSizeUpperBound
        size = sizeof(maxPacketSize);
        AudioFileGetProperty(audioFile, kAudioFilePropertyPacketSizeUpperBound, &size, &maxPacketSize);
        if (maxPacketSize > gBufferSizeBytes)
        {
            maxPacketSize = gBufferSizeBytes;
            NSLog(@"*** Warning *** GBMusicTrack - initWithPath: had to limit packet size requested for file: %@", [path lastPathComponent]);
        }
        numPacketsToRead = gBufferSizeBytes / maxPacketSize;
        
        //给包的描述分配空间
        packetDescs = malloc(sizeof(AudioStreamPacketDescription) * numPacketsToRead);
    }
    else
    {
        // 对于CBR 数据 (Constant BitRate), 使用合适的数据填充到混村中
        numPacketsToRead = gBufferSizeBytes / dataFormat.mBytesPerPacket;
        
        // 这种包的描述不需要
        packetDescs = nil;
    }
    
    // see if file uses a magic cookie (a magic cookie is meta data which some formats use)
    AudioFileGetPropertyInfo(audioFile, kAudioFilePropertyMagicCookieData, &size, nil);
    if (size > 0)
    {
        // 把缓存数据从文件中copy出来放到音频队列中
        cookie = malloc(sizeof(char) * size);
        AudioFileGetProperty(audioFile, kAudioFilePropertyMagicCookieData, &size, cookie);
        AudioQueueSetProperty(queue, kAudioQueueProperty_MagicCookie, cookie, size);
        free(cookie);
    }

    AudioQueueAddPropertyListener(queue, kAudioQueueProperty_IsRunning, propertyListenerCallback, self);
    
    // 给特定的缓存分配数据
    packetIndex = 0;
    for (i = 0; i < NUM_QUEUE_BUFFERS; i++)
    {
        AudioQueueAllocateBuffer(queue, gBufferSizeBytes, &buffers[i]);
        if ([self readPacketsIntoBuffer:buffers[i]] == 0)
        {
            // 检查读取到缓存中的包的大小
            break;
        }
    }
    repeat = NO;
    trackClosed = NO;
    trackEnded = NO;
    gThereIsAnActiveTrack = YES;
    return self;
}

 

 

 

//  Created by Jake Peterson (AnotherJake) on 7/6/08.
//  Copyright 2008 Jake Peterson. All rights reserved.

 

 

防盗加个链接：

   作者：Alexliu（alex dotNet Learning）
   出处：http://alexliu.cnblogs.com/