AVFoundation-仅合并视频，仅显示第一个 [英] AVFoundation - combine videos only one the first is displayed
问题描述
我正在尝试采用不同的方式来合并视频.我正在为每个转换创建新的轨道.
I am trying to take a different approach at combining videos. I am creating a new track for each transformation.
此代码的问题是，显示了第一个视频，所有其他视频均为黑色.
The problem with this code is that the first video is shown and all others are black.
整个部分的音频覆盖都是正确的.似乎视频没有被合成，因为文件的大小为5 M(应为25 M时). 5M大小与第一个剪辑和音轨的大小相关.所有的AVAsets似乎都是有效的.这些文件确实存在于文件系统上.这是代码:
The audio overlay is correct for the entire segment. It looks like the video is not brought in to the composition because the size of the file is 5 M when it should be about 25M. The 5M size correlates to the size of the first clip and the audio track. All of the AVAssets appear to be valid. The files do exist on the file system. Here is the code:
- (void)mergeVideos:(NSMutableArray *)assets withCompletion:(void (^)(NSString *))completion; {
// NSMutableArray *instructions = [NSMutableArray new];
CGSize size = CGSizeZero;
CMTime currentstarttime = kCMTimeZero;
int tracknumber = 1;
int32_t commontimescale = 600;
CMTime time = kCMTimeZero;
AVMutableComposition *mutableComposition = [AVMutableComposition composition];
NSMutableArray *instructions = [[NSMutableArray alloc] init];
for (NSURL *assetUrl in assets) {
AVAsset *asset = [AVAsset assetWithURL:assetUrl];
NSLog(@"Number of tracks: %lu Incremental track number %i", (unsigned long)[[asset tracks] count], tracknumber);
// make sure the timescales are correct for these tracks
CMTime cliptime = CMTimeConvertScale(asset.duration, commontimescale, kCMTimeRoundingMethod_QuickTime);
AVMutableCompositionTrack *videoCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *assetTrack = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject;
NSLog(@"Running time: value = %lld timescale = %d", time.value, time.timescale);
NSLog(@"Asset length: value = %lld timescale = %d", asset.duration.value, asset.duration.timescale);
NSLog(@"Converted Scale: value = %lld timescale = %d", cliptime.value, cliptime.timescale);
NSError *error;
[videoCompositionTrack insertEmptyTimeRange:CMTimeRangeMake(kCMTimeZero, time)];
[videoCompositionTrack insertTimeRange:CMTimeRangeMake(time, cliptime)
ofTrack:assetTrack
atTime:time
error:&error];
if (error) {
NSLog(@"Error - %@", error.debugDescription);
}
// this flips the video temporarily for the front facing camera
AVMutableVideoCompositionLayerInstruction *inst = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoCompositionTrack];
// set the flipping trasform to the correct tracks
if ((tracknumber == 2) || (tracknumber == 4) || (tracknumber == 6) || (tracknumber == 8) || (tracknumber == 10)) {
CGAffineTransform transform = CGAffineTransformMakeRotation(M_PI);
[inst setTransform:transform atTime:time];
} else {
CGAffineTransform transform = assetTrack.preferredTransform;
[inst setTransform:transform atTime:time];
}
// don't block the other videos with your black - needs to be the incremental time
[inst setOpacity:0.0 atTime:time];
// add the instructions to the overall array
[instructions addObject:inst];
// increment the total time after w use it for this iteration
time = CMTimeAdd(time, cliptime);
if (CGSizeEqualToSize(size, CGSizeZero)) {
size = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject.naturalSize;;
}
// incrememt the track counter
tracknumber++;
}
AVMutableVideoCompositionInstruction *mainVideoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainVideoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, time);
mainVideoCompositionInstruction.layerInstructions = instructions;
// bring all of the video together in the main composition
AVMutableVideoComposition *mainVideoComposition = [AVMutableVideoComposition videoComposition];
mainVideoComposition.instructions = [NSArray arrayWithObject:mainVideoCompositionInstruction];
// setup the audio
AVMutableCompositionTrack *audioCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
// Grab the path, make sure to add it to your project!
NSURL *soundURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"bink-bink-lexus-3" ofType:@"aif"]];
AVURLAsset *soundAsset = [AVURLAsset assetWithURL:soundURL];
NSError *error;
// add audio to the entire track
[audioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, mutableComposition.duration)
ofTrack:[soundAsset tracksWithMediaType:AVMediaTypeAudio][0]
atTime:kCMTimeZero
error:&error];
// Set the frame duration to an appropriate value (i.e. 30 frames per second for video).
// mainVideoComposition.frameDuration = CMTimeMake(1, 30);
mainVideoComposition.renderSize = size;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths firstObject];
int number = arc4random_uniform(10000);
self.outputFile = [documentsDirectory stringByAppendingFormat:@"/export_%i.mov",number];
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mutableComposition
presetName:AVAssetExportPreset1280x720];
exporter.outputURL = [NSURL fileURLWithPath:self.outputFile];
//Set the output file type
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.shouldOptimizeForNetworkUse = YES;
dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_group_leave(group);
}];
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
NSLog(@"Export File (Final) - %@", self.outputFile);
completion(self.outputFile);
});
}
推荐答案
您的问题是，通过使用多个AVMutableCompositionTracks并在kCMTimeZero之后的某个时间插入一个时间范围，会导致每个后续轨道的媒体都出现在合成中在kCMTimeZero.您需要使用
Your problem is that by using multiple AVMutableCompositionTracks and inserting a time range at a time after kCMTimeZero, you are causing each subsequent track to have its media appear in the composition at kCMTimeZero. You need to use insertEmptyTimeRange: if you want to pursue this route. It will move the media for that particular track forward in time by the duration of the empty range you insert.
或者，一种更简单的方法是使用单个AVMutableCompositionTrack.
Or, a much much easier way would be to use a single AVMutableCompositionTrack.
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