iOS开发- 音频截取

#pragma mark - 截取音频方法
- (void)captureSongAction
{
    CocoaSecurityResult * result = [CocoaSecurity md5:[[NSDate date] description]];
    // 创建音频文件
    NSArray *dirs = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask,YES);
    NSString *documentsDirectoryPath = [dirs objectAtIndex:0];
    NSString *filePath = [documentsDirectoryPath stringByAppendingPathComponent:@"CaptureMusic"];
    if (![[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        [[NSFileManager defaultManager] createDirectoryAtPath:filePath withIntermediateDirectories:YES attributes:nil error:nil];
    }
    
    NSString *tempMusicPath = [NSString stringWithFormat:@"%@/%@.m4a",filePath, result.hex];
    
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:self.asset];
    if ([compatiblePresets containsObject:AVAssetExportPresetMediumQuality]) {
        
        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]
                                               initWithAsset:self.asset presetName:AVAssetExportPresetAppleM4A];
        // Implementation continues.
        
        CMTime startTime = CMTimeMake(self.startTime, 1);
        CMTime stopTime = CMTimeMake(self.startTime+self.playTime, 1);
        CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);
        
        
        NSURL *furl = [NSURL fileURLWithPath:tempMusicPath];
        exportSession.outputURL = furl;
        exportSession.outputFileType = AVFileTypeAppleM4A;
        exportSession.timeRange = exportTimeRange; // 截取时间

        [exportSession exportAsynchronouslyWithCompletionHandler:^{
            
            switch ([exportSession status]) {
                case AVAssetExportSessionStatusFailed:
                    
                    NSLog(@"Export failed: %@", [[exportSession error] localizedDescription]);
                    break;
                case AVAssetExportSessionStatusCancelled:
                    
                    NSLog(@"Export canceled");
                    break;
                default:
                    [self addCertainAlertViewWithTitle:LocalizedString(@"AlertViewTitleSysPrompt") Message:@"截取成功"];
                    NSLog(@"保存成功");
            }
        }];
        
    }
   
}
           

因为iOS的输出格式不支持.mp3,只能设置为.m4a的音频文件.

AVAssetExportSession支持导出的文件类型如下所示:

<__NSArrayI 0x158c0d60>(

com.apple.quicktime-movie,

com.apple.m4a-audio,

public.mpeg-4,

com.apple.m4v-video,

public.3gpp,

org.3gpp.adaptive-multi-rate-audio,

com.microsoft.waveform-audio,

public.aiff-audio,

public.aifc-audio,

com.apple.coreaudio-format

)