iOS的音频修剪 [英] iOS Audio Trimming

问题描述

我搜索了很多，但没有找到任何相关信息......我的工作在iOS上的音频文件，并在这里就是我想要做的...

I searched a lot and couldn't find anything relevant... I am working on iOS audio files and here is what I want to do...

1. 录制音频和保存剪辑（经过，我这样做是使用 AVAudioRecorder ）


2. 改变音高（查了一下，这篇用狄拉克）


3. 修整：（

我有两个标志，即开始与放大器;结束偏移量和使用这种信息，我想剪裁记录的文件，并希望把它救回来。我不想用闹，因为后来我要玩的所有记录文件同步（就像在时间轴Flash影片剪辑），然后最后我要导出为一个音频文件。

I have two markers i.e. starting & ending offset and using this info I want to trim recorded file and want to save it back. I don't want to use "seek" because later on I want to play all recorded files in sync (just like flash movie clips in timeline) and then finally I want to export as one audio file.

推荐答案

下面是我用从pre-现有文件修剪音频code。你需要改变M4A相关的常数，如果你已经储存或保存为另一种格式。

Here's the code that I've used to trim audio from a pre-existing file. You'll need to change the M4A related constants if you've saved or are saving to another format.

- (BOOL)trimAudio
{
    float vocalStartMarker = <starting time>;
    float vocalEndMarker = <ending time>;

    NSURL *audioFileInput = <your pre-existing file>;
    NSURL *audioFileOutput = <the file you want to create>;

    if (!audioFileInput || !audioFileOutput)
    {
        return NO;
    }

    [[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];
    AVAsset *asset = [AVAsset assetWithURL:audioFileInput];

    AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset
                                                                            presetName:AVAssetExportPresetAppleM4A];

    if (exportSession == nil)
    {        
        return NO;
    }

    CMTime startTime = CMTimeMake((int)(floor(vocalStartMarker * 100)), 100);
    CMTime stopTime = CMTimeMake((int)(ceil(vocalEndMarker * 100)), 100);
    CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);

    exportSession.outputURL = audioFileOutput;
    exportSession.outputFileType = AVFileTypeAppleM4A;
    exportSession.timeRange = exportTimeRange;

    [exportSession exportAsynchronouslyWithCompletionHandler:^
     {
         if (AVAssetExportSessionStatusCompleted == exportSession.status)
         {
             // It worked!
         } 
         else if (AVAssetExportSessionStatusFailed == exportSession.status)
         {
             // It failed...
         }
     }];

    return YES;
}

有也技术Q＆安培; A 1730 ，这给出了一个略为详细的方法。

There's also Technical Q&A 1730, which gives a slightly more detailed approach.

这篇关于iOS的音频修剪的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！