IOS - 合并两个音频并把它作为一个MP3格式

Question

这里我有两个音频文件，我成功地结合这两种音频文件，但它的回报率只有.m4a的格式，我需要mp3格式

- (BOOL) combineVoices1 
{ 
    NSError *error = nil; 
    BOOL ok = NO; 


    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 


    CMTime nextClipStartTime = kCMTimeZero; 
    //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack. 
    AVMutableComposition *composition = [[AVMutableComposition alloc] init]; 

    AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
    [compositionAudioTrack setPreferredVolume:0.8]; 
    NSString *soundOne =[[NSBundle mainBundle]pathForResource:@"test1" ofType:@"caf"]; 
    NSURL *url = [NSURL fileURLWithPath:soundOne]; 
    AVAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil]; 
    NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio]; 
    AVAssetTrack *clipAudioTrack = [[avAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]; 
    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil]; 

    AVMutableCompositionTrack *compositionAudioTrack1 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
    [compositionAudioTrack setPreferredVolume:0.3]; 
    NSString *soundOne1 =[[NSBundle mainBundle]pathForResource:@"test" ofType:@"caf"]; 
    NSURL *url1 = [NSURL fileURLWithPath:soundOne1]; 
    AVAsset *avAsset1 = [AVURLAsset URLAssetWithURL:url1 options:nil]; 
    NSArray *tracks1 = [avAsset1 tracksWithMediaType:AVMediaTypeAudio]; 
    AVAssetTrack *clipAudioTrack1 = [[avAsset1 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]; 
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack1 atTime:kCMTimeZero error:nil]; 


    AVMutableCompositionTrack *compositionAudioTrack2 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
    [compositionAudioTrack2 setPreferredVolume:1.0]; 
    NSString *soundOne2 =[[NSBundle mainBundle]pathForResource:@"song" ofType:@"caf"]; 
    NSURL *url2 = [NSURL fileURLWithPath:soundOne2]; 
    AVAsset *avAsset2 = [AVURLAsset URLAssetWithURL:url2 options:nil]; 
    NSArray *tracks2 = [avAsset2 tracksWithMediaType:AVMediaTypeAudio]; 
    AVAssetTrack *clipAudioTrack2 = [[avAsset2 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]; 
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset2.duration) ofTrack:clipAudioTrack2 atTime:kCMTimeZero error:nil]; 



    AVAssetExportSession *exportSession = [AVAssetExportSession 
              exportSessionWithAsset:composition 
              presetName:AVAssetExportPresetAppleM4A]; 
    if (nil == exportSession) return NO; 

    NSString *soundOneNew = [documentsDirectory stringByAppendingPathComponent:@"combined10.m4a"]; 
    //NSLog(@"Output file path - %@",soundOneNew); 

    // configure export session output with all our parameters 
    exportSession.outputURL = [NSURL fileURLWithPath:soundOneNew]; // output path 
    exportSession.outputFileType = AVFileTypeAppleM4A; // output file type 

    // perform the export 
    [exportSession exportAsynchronouslyWithCompletionHandler:^{ 

     if (AVAssetExportSessionStatusCompleted == exportSession.status) { 
      NSLog(@"AVAssetExportSessionStatusCompleted"); 
     } else if (AVAssetExportSessionStatusFailed == exportSession.status) { 
      // a failure may happen because of an event out of your control 
      // for example, an interruption like a phone call comming in 
      // make sure and handle this case appropriately 
      NSLog(@"AVAssetExportSessionStatusFailed"); 
     } else { 
      NSLog(@"Export Session Status: %d", exportSession.status); 
     } 
    }]; 


    return YES; 


} 

请任何机构请帮我

Answer 1

你是在尝试转换为MP3的麻烦世界。涉及昂贵的专利许可证。你可以找到寻找解决方案的人的问题，而且没有好的回应。

如果你正在寻找只是为自己做点事你自己，你可以尝试FFmpeg的，但他们有一些非常严重的法律事项免责声明此处

这条线尤其令人担忧：

Q：将我整个FFmpeg核心纳入我自己的商业产品 完全可以吗？

- 答：你可能在这里有一个问题。已经有公司在其产品中使用FFmpeg的情况。 这些公司发现，一旦你开始试图通过专利技术赚钱 ，这些专利的所有者将在 之后获得许可费用。值得注意的是，MPEG LA对于收集MPEG相关技术的 保持警惕和勤奋。