我有 2 个音频文件audioFile1.m4a
和audioFile2.m4a
. 我想创建一个级联音频,其中一个又一个combined.m4a
包含audioFile1.m4a
and audioFile2.m4a
。我使用了下面的代码,我的问题tracksWithMediaType
总是返回空数组。audioIds 包含音频文件名。
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];
for (int i = 0; i< [audioIds count]; i++) {
NSString *audioFileName = [audioIds objectAtIndex:i];
//Build the filename with path
NSString *soundOne = [documentsDirectory stringByAppendingPathComponent:audioFileName];
NSLog(@"voice file - %@",soundOne);
NSURL *url = [NSURL fileURLWithPath:soundOne];
AVAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil];
NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio];
if ([tracks count] == 0)
return;
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);
}
// create the export session
// no need for a retain here, the session will be retained by the
// completion handler since it is referenced there
AVAssetExportSession *exportSession = [AVAssetExportSession
exportSessionWithAsset:composition
presetName:AVAssetExportPresetAppleM4A];
if (nil == exportSession) return ;
__block NSString *soundOneNew = [documentsDirectory stringByAppendingPathComponent:@"combined.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: %ld", (long)exportSession.status);
}
}];