Objective-C中如何进行音频处理

在Objective-C中进行音频处理通常使用AVFoundation框架。以下是一些常见的音频处理操作：

1. 播放音频文件：

NSURL *audioFileURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"audioFile" ofType:@"mp3"]];

AVPlayer *player = [AVPlayer playerWithURL:audioFileURL];
[player play];

2. 音频录制：

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
[audioSession setCategory:AVAudioSessionCategoryRecord error:nil];

NSMutableDictionary *settings = [NSMutableDictionary dictionary];
[settings setValue:@(kAudioFormatAppleLossless) forKey:AVFormatIDKey];
[settings setValue:@44100.0 forKey:AVSampleRateKey];
[settings setValue:@1 forKey:AVNumberOfChannelsKey];

AVAudioRecorder *recorder = [[AVAudioRecorder alloc] initWithURL:audioFileURL settings:settings error:nil];
[recorder record];

3. 音频转码：

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

exportSession.outputFileType = AVFileTypeAppleM4A;
exportSession.outputURL = outputURL;

[exportSession exportAsynchronouslyWithCompletionHandler:^{
    if (exportSession.status == AVAssetExportSessionStatusCompleted) {
        NSLog(@"转码成功！");
    }
}];

4. 音频剪切：

AVURLAsset *asset = [AVURLAsset URLAssetWithURL:audioFileURL options:nil];

CMTime startTime = CMTimeMakeWithSeconds(0, 1);
CMTime endTime = CMTimeMakeWithSeconds(10, 1);
CMTimeRange timeRange = CMTimeRangeFromTimeToTime(startTime, endTime);

AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset presetName:AVAssetExportPresetPassthrough];
exportSession.timeRange = timeRange;

[exportSession exportAsynchronouslyWithCompletionHandler:^{
    if (exportSession.status == AVAssetExportSessionStatusCompleted) {
        NSLog(@"剪切成功！");
    }
}];

这些是一些常见的音频处理操作，使用AVFoundation框架可以实现更多高级的音频处理功能。