Question

我正在尝试混合两个音频文件（将一个音频文件放在另一个上面 - 没有拼接在一起）但我正在努力学习IOS上的AVFoundation。我在这里听到了这个答案：How to merge Audio and video using AVMutableCompositionTrack

这就是我所拥有的：

//NSURL *audioFilePath = [NSURL fileURLWithPath:@"var/mobile/Applications/822732B6-67B9-485F-BA44-FAACAB34C4FD/Documents/Coisir Cheoil10_09_2014_1429.m4a"];
NSURL *audioUrl = [NSURL fileURLWithPath:@"var/mobile/Applications/822732B6-67B9-485F-BA44-FAACAB34C4FD/Documents/Robot R-3-311_09_2014_2252.m4a"];
// need to fix link to backing Track
NSURL *backingTrackURL = [NSURL fileURLWithPath:@"var/mobile/Applications/822732B6-67B9-485F-BA44-FAACAB34C4FD/Documents/Robot R-3-316_09_2014_1559.m4a"];// need ot fix the link to this
AVURLAsset* backingTrack = [[AVURLAsset alloc] initWithURL:audioUrl options:nil];
AVURLAsset* voiceTrack = [[AVURLAsset alloc] initWithURL:backingTrackURL options:nil];

AVMutableComposition* mixComposition = [AVMutableComposition composition];

AVMutableCompositionTrack *compositionCommentaryTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];


[compositionCommentaryTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, backingTrack.duration)
                                    ofTrack:[[backingTrack tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0]
                                     atTime:kCMTimeZero
                                      error:nil];

AVMutableCompositionTrack *compositionVoiceTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

[compositionVoiceTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, voiceTrack.duration)
                               ofTrack:[[voiceTrack tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0] atTime:kCMTimeZero error:nil];

AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];

NSString* mixedAudio = @"mixedAudio.m4a";

NSString *exportPath = [NSTemporaryDirectory() stringByAppendingString:mixedAudio];
NSURL *exportURL = [NSURL fileURLWithPath:exportPath];

if ([[NSFileManager defaultManager]fileExistsAtPath:exportPath]) {
    [[NSFileManager defaultManager]removeItemAtPath:exportPath error:nil];
}
_assetExport.outputFileType = @"m4a";
_assetExport.outputURL = exportURL;
_assetExport.shouldOptimizeForNetworkUse = YES;

[_assetExport exportAsynchronouslyWithCompletionHandler:^{
    NSLog(@"Completed Sucessfully");
}];

The code fails when I try to set the timeranges with an error index 0 beyond bounds for empty array.  I take it that backing track does not include tracksWithMediaTye:AvMediaTypeAudio and that is why that fails.

我怀疑是因为我正在加载.m4a音频文件而不是像StackOverflow上的原始答案那样的视频文件。所以我的问题是如何混合两个单独的音频文件并将它们保存为新的组合文件。用法是我有一个支持轨道，用户录制他们自己的人声，然后可以将他们的人声与背景音轨混合并将混合音频发送给他们自己。

感谢您的任何建议。我发现AVFoundation非常令人生畏。

Answer 1

我发布了我最终开始工作的代码，以防其他人试图做同样的事情并且想要一些代码示例（上面我的问题我怀疑音频文件不是＆＃39;正确加载）

 [self showActivityIndicator]; // This code takes a while so show the user an activity Indicator
AVMutableComposition *composition = [AVMutableComposition composition];
NSArray* tracks = [NSArray arrayWithObjects:@"backingTrack", @"RobotR33", nil];
NSString* audioFileType = @"wav";

for (NSString* trackName in tracks) {
    AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:trackName ofType:audioFileType]]options:nil];

    AVMutableCompositionTrack* audioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
                                                                     preferredTrackID:kCMPersistentTrackID_Invalid];

    NSError* error;
    [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration) ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0] atTime:kCMTimeZero error:&error];
    if (error)
    {
        NSLog(@"%@", [error localizedDescription]);
    }
}
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetAppleM4A];

NSString* mixedAudio = @"mixedAudio.m4a";

NSString *exportPath = [NSTemporaryDirectory() stringByAppendingString:mixedAudio];
NSURL *exportURL = [NSURL fileURLWithPath:exportPath];

if ([[NSFileManager defaultManager]fileExistsAtPath:exportPath]) {
    [[NSFileManager defaultManager]removeItemAtPath:exportPath error:nil];
}
_assetExport.outputFileType = AVFileTypeAppleM4A;
_assetExport.outputURL = exportURL;
_assetExport.shouldOptimizeForNetworkUse = YES;

[_assetExport exportAsynchronouslyWithCompletionHandler:^{
    [self hideActivityIndicator];
    NSLog(@"Completed Sucessfully");
}];

Answer 2

适用于Swift 3

    showActivityIndicator()  
    var composition = AVMutableComposition()
    var tracks: [Any] = ["backingTrack", "RobotR33"]
    var audioFileType: String = "wav"
    for trackName: String in tracks {
        var audioAsset = AVURLAsset(url: URL(fileURLWithPath: Bundle.main.path(forResource: trackName, ofType: audioFileType)), options: nil)
        var audioTrack: AVMutableCompositionTrack? = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
        var error: Error?
        try? audioTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, audioAsset.duration), of: audioAsset.tracks(withMediaType: AVMediaTypeAudio)[0], atTime: kCMTimeZero)
        if error != nil {
            print("\(error?.localizedDescription)")
        }
    }
    var _assetExport = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
//  Converted with Swiftify v1.0.6355 - https://objectivec2swift.com/
var mixedAudio: String = "mixedAudio.m4a"
var exportPath: String = NSTemporaryDirectory() + (mixedAudio)
var exportURL = URL(fileURLWithPath: exportPath)
if FileManager.default.fileExists(atPath: exportPath) {
    try? FileManager.default.removeItem(atPath: exportPath)
}
assetExport.outputFileType = AVFileTypeAppleM4A
assetExport.outputURL = exportURL
assetExport.shouldOptimizeForNetworkUse = true
assetExport.exportAsynchronously(withCompletionHandler: {() -> Void in
    self.hideActivityIndicator()
    print("Completed Sucessfully")
})

在IOS上使用AVComposition混合两个音频文件

2 个答案: