Question

在墙上撞了好几次并尝试了不同的处理方法，需要花费很长时间来处理（改变不同音量的MP3文件）我决定将这个问题发布给每个人，希望找到一个有答案的人。< / p>

我有一个AVMutableComposition，用于音频和视频的几个AVMutableCompositionTrack。混音工作正常，但音轨的音量调节不起作用，导出时失败。

以下是我使用的代码：

AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVURLAsset *soundTrackAsset = [[AVURLAsset alloc]initWithURL:trackTempProcessedURL options:nil];

//ADDING AUDIO
AVMutableCompositionTrack *compositionAudioSoundTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:trackIDSoundTrack];
[compositionAudioSoundTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration) 
                                    ofTrack:[[soundTrackAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] 
                                     atTime:CMTimeAdd(cmTimeDifference,startTime) error:nil];

NSArray *tracksToDuck = [mixComposition tracksWithMediaType:AVMediaTypeAudio];
NSMutableArray *trackMixArray = [NSMutableArray array];
for (NSInteger i = 0; i < [tracksToDuck count]; i++) {
    AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:[tracksToDuck objectAtIndex:i]];
    [trackMix setVolume:volume atTime:kCMTimeZero];   
    [trackMixArray addObject:trackMix];
 }
 audioMix = [AVMutableAudioMix audioMix];
 audioMix.inputParameters = trackMixArray;

//ADDING VIDEO
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:frontAssetURL options:nil];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) 
                               ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
                                atTime:startTime error:nil];

//EXPORTING
_assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName: AVAssetExportPresetPassthrough];

_assetExport.outputFileType = AVFileTypeQuickTimeMovie; 
_assetExport.outputURL = exportUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
_assetExport.audioMix = audioMix;  

[_assetExport exportAsynchronouslyWithCompletionHandler:
 ^(void ) { 
 ...

没有音频混音器，一切都很好混合但是当我尝试改变音量时，导出会给我一个错误：

AVFoundationErrorDomain Error: 11822

Answer 1

AVMutableAudioMixInputParameters需要设置“trackID”来指示哪些音轨应该应用参数。

for (NSInteger i = 0; i < [tracksToDuck count]; i++) {
    AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:[tracksToDuck objectAtIndex:i]];
    [trackMix setVolume:volume atTime:kCMTimeZero];   

//+++++code
    AVMutableCompositionTrack * track = [tracksToDuck objectAtIndex:i]
    [trackMix setTrackID:[track trackID]];

    [trackMixArray addObject:trackMix];
}

如何在AVMutableComposition中更改轨道的音量

1 个答案: