我目前正在研究合併所需數量視頻的iOS應用程序。一旦用戶點擊該按鈕合併的視頻,該視頻被加入,然後開始玩使用AVPlayer爲:iOS中的視頻編輯問題
CMTime nextClipStartTime = kCMTimeZero;
NSInteger i;
CMTime transitionDuration = CMTimeMake(1, 1); // Default transition duration is one second.
// Add two video tracks and two audio tracks.
AVMutableCompositionTrack *compositionVideoTracks[2];
AVMutableCompositionTrack *compositionAudioTracks[2];
compositionVideoTracks[0] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
compositionVideoTracks[1] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
compositionAudioTracks[0] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
compositionAudioTracks[1] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
CMTimeRange *passThroughTimeRanges = alloca(sizeof(CMTimeRange) * [self.selectedAssets count]);
CMTimeRange *transitionTimeRanges = alloca(sizeof(CMTimeRange) * [self.selectedAssets count]);
// Place clips into alternating video & audio tracks in composition, overlapped by transitionDuration.
for (i = 0; i < [self.selectedAssets count]; i++)
{
NSInteger alternatingIndex = i % 2; // alternating targets: 0, 1, 0, 1, ...
AVURLAsset *asset = [self.selectedAssets objectAtIndex:i];
NSLog(@"number of tracks %d",asset.tracks.count);
CMTimeRange assetTimeRange;
assetTimeRange.start = kCMTimeZero;
assetTimeRange.duration = asset.duration;
NSValue *clipTimeRange = [NSValue valueWithCMTimeRange:assetTimeRange];
CMTimeRange timeRangeInAsset;
if (clipTimeRange)
timeRangeInAsset = [clipTimeRange CMTimeRangeValue];
else
timeRangeInAsset = CMTimeRangeMake(kCMTimeZero, [asset duration]);
AVAssetTrack *clipVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[compositionVideoTracks[alternatingIndex] insertTimeRange:timeRangeInAsset ofTrack:clipVideoTrack atTime:nextClipStartTime error:nil];
AVAssetTrack *clipAudioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
[compositionAudioTracks[alternatingIndex] insertTimeRange:timeRangeInAsset ofTrack:clipAudioTrack atTime:nextClipStartTime error:nil];
// Remember the time range in which this clip should pass through.
// Every clip after the first begins with a transition.
// Every clip before the last ends with a transition.
// Exclude those transitions from the pass through time ranges.
passThroughTimeRanges[i] = CMTimeRangeMake(nextClipStartTime, timeRangeInAsset.duration);
if (i > 0) {
passThroughTimeRanges[i].start = CMTimeAdd(passThroughTimeRanges[i].start, transitionDuration);
passThroughTimeRanges[i].duration = CMTimeSubtract(passThroughTimeRanges[i].duration, transitionDuration);
}
if (i+1 < [self.selectedAssets count]) {
passThroughTimeRanges[i].duration = CMTimeSubtract(passThroughTimeRanges[i].duration, transitionDuration);
}
// The end of this clip will overlap the start of the next by transitionDuration.
// (Note: this arithmetic falls apart if timeRangeInAsset.duration < 2 * transitionDuration.)
nextClipStartTime = CMTimeAdd(nextClipStartTime, timeRangeInAsset.duration);
nextClipStartTime = CMTimeSubtract(nextClipStartTime, transitionDuration);
// Remember the time range for the transition to the next item.
transitionTimeRanges[i] = CMTimeRangeMake(nextClipStartTime, transitionDuration);
}
// Set up the video composition if we are to perform crossfade or push transitions between clips.
NSMutableArray *instructions = [NSMutableArray array];
// Cycle between "pass through A", "transition from A to B", "pass through B", "transition from B to A".
for (i = 0; i < [self.selectedAssets count]; i++)
{
NSInteger alternatingIndex = i % 2; // alternating targets
// Pass through clip i.
AVMutableVideoCompositionInstruction *passThroughInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
passThroughInstruction.timeRange = passThroughTimeRanges[i];
AVMutableVideoCompositionLayerInstruction *passThroughLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[alternatingIndex]];
passThroughInstruction.layerInstructions = [NSArray arrayWithObject:passThroughLayer];
[instructions addObject:passThroughInstruction];
AVMutableVideoCompositionLayerInstruction *fromLayer;
AVMutableVideoCompositionLayerInstruction *toLayer;
if (i+1 < [self.selectedAssets count])
{
// Add transition from clip i to clip i+1.
AVMutableVideoCompositionInstruction *transitionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
transitionInstruction.timeRange = transitionTimeRanges[i];
fromLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[alternatingIndex]];
toLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[1-alternatingIndex]];
// Fade out the fromLayer by setting a ramp from 1.0 to 0.0.
[fromLayer setOpacityRampFromStartOpacity:1.0 toEndOpacity:0.0 timeRange:transitionTimeRanges[i]];
transitionInstruction.layerInstructions = [NSArray arrayWithObjects:fromLayer, toLayer, nil];
[instructions addObject:transitionInstruction];
}
AVURLAsset *sourceAsset = [AVURLAsset URLAssetWithURL:[self.selectedItemsURL objectAtIndex:i] options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey]];
AVAssetTrack *sourceVideoTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
CGSize temp = CGSizeApplyAffineTransform(sourceVideoTrack.naturalSize, sourceVideoTrack.preferredTransform);
CGSize size = CGSizeMake(fabsf(temp.width), fabsf(temp.height));
CGAffineTransform transform = sourceVideoTrack.preferredTransform;
self.videoComposition.renderSize = sourceVideoTrack.naturalSize;
if (size.width > size.height) {
[fromLayer setTransform:transform atTime:sourceAsset.duration];
} else {
float s = size.width/size.height;
CGAffineTransform new = CGAffineTransformConcat(transform, CGAffineTransformMakeScale(s,s));
float x = (size.height - size.width*s)/2;
CGAffineTransform newer = CGAffineTransformConcat(new, CGAffineTransformMakeTranslation(x, 0));
[fromLayer setTransform:newer atTime:sourceAsset.duration];
}
}
self.videoComposition.instructions = instructions;
self.videoComposition.frameDuration = CMTimeMake(1, 30);
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];
NSURL *url = [NSURL fileURLWithPath:myPathDocs];
self.exporter = [[AVAssetExportSession alloc] initWithAsset:self.mixComposition presetName:AVAssetExportPresetMediumQuality];
self.exporter.outputURL=url;
self.exporter.outputFileType = AVFileTypeQuickTimeMovie;
self.exporter.videoComposition = self.videoComposition;
self.exporter.shouldOptimizeForNetworkUse = YES;
self.playerItem = [AVPlayerItem playerItemWithAsset:self.mixComposition];
self.playerItem.videoComposition = self.videoComposition;
AVPlayer *player = [AVPlayer playerWithPlayerItem:self.playerItem];
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:player];
[playerLayer setFrame:CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height)];
[[[self imageView] layer] addSublayer:playerLayer];
playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[player play];
[[NSNotificationCenter defaultCenter]
addObserver:self selector:@selector(checkPlayEnded) name:AVPlayerItemDidPlayToEndTimeNotification object:self.playerItem];
我目前面臨着以下問題:
如果一個視頻是在肖像,以及其他景觀,我如何能夠在風景中旋轉肖像視頻,因爲我的視角是橫向的,但縱向視頻保留其原來的? (我正在加載存儲在相機膠捲中的視頻,而不是將它們記錄在我的應用程序中)
忽略上述問題,如果我合併任何數量的視頻,它們都可以正常工作。一旦我將該新視頻保存到我的圖書館中,然後再次將其加載到我的應用中,並嘗試與其他一些新視頻一起加入該視頻,分辨率就會受到干擾,儘管這兩個視頻如果在應用中單獨播放,效果都很好。我該如何解決這個問題?
(我曾試圖按照WWDC 2010的視頻編輯教程,所以這段代碼是從那裏提取。)
如果你現在還沒有得到解決方案,讓我知道,我知道如何解決這個問題.... –
@ParvezBelim感謝您的關注。我實施了以下解決方案,幫助我解決了這些問題。 1.每當用戶想要在項目中添加視頻時,將檢查其方向,如果它不是橫向,則將其轉換爲橫向,然後添加到項目中。 –
2.問題2是由於AVExportSession導出的視頻和攝像頭創建的視頻的分辨率不同所致。所以現在,他們首先轉換爲預先選定的分辨率,然後添加到項目中,這導致項目中的所有視頻具有相同的分辨率,因此一切正常。 –