ios - 读入声音文件，添加回声并写入新的声音文件

Question

我正在尝试完成以下任务:

将声音文件读入内存

将其分成多个块，并以预定义的偏移量(2个可能的偏移量值)添加回波。

另存为新文件

我有以下代码将声音文件读入内存:

NSURL   *urlToCAF = [NSURL URLWithString:@"simple-drum-beat.caf"];

ExtAudioFileRef caf;
OSStatus    status;

status = ExtAudioFileOpenURL((__bridge CFURLRef)urlToCAF, &caf);
if(noErr == status) {
    // request float format
    const UInt32 NumFrames = 1024;
    const int ChannelsPerFrame = 1;  // Mono, 2 for Stereo

    // request float format
    AudioStreamBasicDescription clientFormat;
    clientFormat.mChannelsPerFrame = ChannelsPerFrame;
    clientFormat.mSampleRate = 44100;

    clientFormat.mFormatID = kAudioFormatLinearPCM;
    clientFormat.mFormatFlags = kAudioFormatFlagIsFloat | kAudioFormatFlagIsNonInterleaved; // float
    int cmpSize = sizeof(float);
    int frameSize = cmpSize*ChannelsPerFrame;
    clientFormat.mBitsPerChannel = cmpSize*8;
    clientFormat.mBytesPerPacket = frameSize;
    clientFormat.mFramesPerPacket = 1;
    clientFormat.mBytesPerFrame = frameSize;

    status = ExtAudioFileSetProperty(caf, kExtAudioFileProperty_ClientDataFormat, sizeof(clientFormat), &clientFormat);
    if(noErr != status) { /* handle it */ }

    while(1) {
        float   buf[ChannelsPerFrame*NumFrames];
        AudioBuffer ab = { ChannelsPerFrame, sizeof(buf), buf };
        AudioBufferList abl;
        abl.mNumberBuffers = 1;
        abl.mBuffers[0] = ab;

        UInt32  ioNumFrames = NumFrames;
        status = ExtAudioFileRead(caf, &ioNumFrames, &abl);

        if(noErr == status) {
            // do something here
        }
    }

    // later
    status = ExtAudioFileDispose(caf);
    if(noErr != status) { /* hmm */ }
}

您能否为我提供必要的代码，以便将回声添加到每个块中，然后将声音另存为新文件？

我很感激。

Answer 1

这与“请为我编写代码”接壤

如果您在缓冲器中有声波，则回声很简单:

out[k] = in[k] + in[k-30]

保存到文件我很确定您可以在Google上找到它。尝试让您的问题询问一件事。

我建议研究 http://theamazingaudioengine.com/-它使生活变得更加轻松!