在我的应用程序中,我合并了多个 .m4a
音频文件。为了合并音频文件,我使用下面的代码。
CMTime nextClipStartTime = kCMTimeZero;
AVMutableComposition *composition = [[AVMutableComposition alloc] init];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
for(NSString * str in filesNamesArray)
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:str];
NSURL *url = [[NSURL alloc] initFileURLWithPath:path];
AVAsset *avAsset = [[AVURLAsset alloc] initWithURL:url options:nil];
NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio];
if ([tracks count] == 0)
{
NSLog(@"Tracks = %lu",(unsigned long)[tracks count]);
return;
}
NSLog(@"%@",avAsset);
CMTimeRange timeRangeInAsset = CMTimeRangeMake(kCMTimeZero, [avAsset duration]);
AVAssetTrack *clipAudioTrack = [[avAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
ok = [compositionAudioTrack insertTimeRange:timeRangeInAsset ofTrack:clipAudioTrack atTime:nextClipStartTime error:&error];
if (!ok) {
NSLog(@"Current Video Track Error: %@",error);
}
nextClipStartTime = CMTimeAdd(nextClipStartTime, timeRangeInAsset.duration);
}
有时“tracksWithMediaType”返回空数组。为什么会发生这种情况以及任何帮助将不胜感激。
最佳答案
当您创建 AVAsset 时:
AVAsset *avAsset = [[AVURLAsset alloc] initWithURL:url options:nil];
Assets 必须在准备使用之前加载其轨道:
[avAsset loadValuesAsynchronouslyForKeys:@"tracks" completionHandler: ^{
AVKeyValueStatus status = [avAsset statusOfValueForKey:@"tracks" error:nil];
if (status == AVKeyValueStatusLoaded) {
// Asset is ready now
}
}];
关于ios - trackWithMediaType 有时返回 0 首轨道,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38439299/