我目前有一个iPhone应用程序，可以让用户拍摄视频，上传到服务器，并允许其他人从应用程序中查看他们的视频。 在我创建网站以查看不同的视频（以及其他内容）之前，从未遇到过视频定位问题。
我从网络服务中获取视频，并使用videojs使用ajax加载它们，但每一个都向左旋转90度。从我读过的内容来看，听起来像方向信息可以在iOS中读取，但不能在网站上读取。 在发送到服务器之前，有没有办法在iPhone上保存视频的新方向？
答案 0 :(得分：1)
似乎发生此问题是因为videojs无法读取方向。此处的信息：http://help.videojs.com/discussions/problems/1508-video-orientation-for-iphone-wrong
根据隐含的解决方案，您应该检查以确保在保存视频时使用AVFramework设置方向值。有关如何执行此操作的信息可在此前的堆栈溢出帖子中找到：How do I set the orientation for a frame-by-frame-generated video using AVFoundation?
答案 1 :(得分：1)
//change Orientation Of video
//in videoorientation.h
#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
@interface videoorientationViewController : UIViewController
@property AVMutableComposition *mutableComposition;
@property AVMutableVideoComposition *mutableVideoComposition;
@property AVMutableAudioMix *mutableAudioMix;
@property AVAssetExportSession *exportSession;
- (void)performWithAsset : (NSURL *)moviename;
@end
In //viewcontroller.m
- (void)performWithAsset : (NSURL *)moviename
{
self.mutableComposition=nil;
self.mutableVideoComposition=nil;
self.mutableAudioMix=nil;
// NSString* filename = [NSString stringWithFormat:@"temp1.mov"];
//
// NSLog(@"file name== %@",filename);
//
// [[NSUserDefaults standardUserDefaults]setObject:filename forKey:@"currentName"];
// NSString* path = [NSTemporaryDirectory() stringByAppendingPathComponent:filename];
// NSLog(@"file number %i",_currentFile);
// NSURL* url = [NSURL fileURLWithPath:path];
// NSString *videoURL = [[NSBundle mainBundle] pathForResource:@"Movie" ofType:@"m4v"];
AVAsset *asset = [[AVURLAsset alloc] initWithURL:moviename options:nil];
AVMutableVideoCompositionInstruction *instruction = nil;
AVMutableVideoCompositionLayerInstruction *layerInstruction = nil;
CGAffineTransform t1;
CGAffineTransform t2;
AVAssetTrack *assetVideoTrack = nil;
AVAssetTrack *assetAudioTrack = nil;
// Check if the asset contains video and audio tracks
if ([[asset tracksWithMediaType:AVMediaTypeVideo] count] != 0) {
assetVideoTrack = [asset tracksWithMediaType:AVMediaTypeVideo][0];
}
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {
assetAudioTrack = [asset tracksWithMediaType:AVMediaTypeAudio][0];
}
CMTime insertionPoint = kCMTimeZero;
NSError *error = nil;
// Step 1
// Create a composition with the given asset and insert audio and video tracks into it from the asset
if (!self.mutableComposition) {
// Check whether a composition has already been created, i.e, some other tool has already been applied
// Create a new composition
self.mutableComposition = [AVMutableComposition composition];
// Insert the video and audio tracks from AVAsset
if (assetVideoTrack != nil) {
AVMutableCompositionTrack *compositionVideoTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetVideoTrack atTime:insertionPoint error:&error];
}
if (assetAudioTrack != nil) {
AVMutableCompositionTrack *compositionAudioTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetAudioTrack atTime:insertionPoint error:&error];
}
}
// Step 2
// Translate the composition to compensate the movement caused by rotation (since rotation would cause it to move out of frame)
t1 = CGAffineTransformMakeTranslation(assetVideoTrack.naturalSize.height, 0.0);
float width=assetVideoTrack.naturalSize.width;
float height=assetVideoTrack.naturalSize.height;
float toDiagonal=sqrt(width*width+height*height);
float toDiagonalAngle = radiansToDegrees(acosf(width/toDiagonal));
float toDiagonalAngle2=90-radiansToDegrees(acosf(width/toDiagonal));
float toDiagonalAngleComple;
float toDiagonalAngleComple2;
float finalHeight = 0.0;
float finalWidth = 0.0;
float degrees=90;
if(degrees>=0&°rees<=90){
toDiagonalAngleComple=toDiagonalAngle+degrees;
toDiagonalAngleComple2=toDiagonalAngle2+degrees;
finalHeight=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple)));
finalWidth=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple2)));
t1 = CGAffineTransformMakeTranslation(height*sinf(degreesToRadians(degrees)), 0.0);
}
else if(degrees>90&°rees<=180){
float degrees2 = degrees-90;
toDiagonalAngleComple=toDiagonalAngle+degrees2;
toDiagonalAngleComple2=toDiagonalAngle2+degrees2;
finalHeight=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple2)));
finalWidth=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple)));
t1 = CGAffineTransformMakeTranslation(width*sinf(degreesToRadians(degrees2))+height*cosf(degreesToRadians(degrees2)), height*sinf(degreesToRadians(degrees2)));
}
else if(degrees>=-90&°rees<0){
float degrees2 = degrees-90;
float degreesabs = ABS(degrees);
toDiagonalAngleComple=toDiagonalAngle+degrees2;
toDiagonalAngleComple2=toDiagonalAngle2+degrees2;
finalHeight=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple2)));
finalWidth=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple)));
t1 = CGAffineTransformMakeTranslation(0, width*sinf(degreesToRadians(degreesabs)));
}
else if(degrees>=-180&°rees<-90){
float degreesabs = ABS(degrees);
float degreesplus = degreesabs-90;
toDiagonalAngleComple=toDiagonalAngle+degrees;
toDiagonalAngleComple2=toDiagonalAngle2+degrees;
finalHeight=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple)));
finalWidth=ABS(toDiagonal*sinf(degreesToRadians(toDiagonalAngleComple2)));
t1 = CGAffineTransformMakeTranslation(width*sinf(degreesToRadians(degreesplus)), height*sinf(degreesToRadians(degreesplus))+width*cosf(degreesToRadians(degreesplus)));
}
// Rotate transformation
t2 = CGAffineTransformRotate(t1, degreesToRadians(degrees));
//t2 = CGAffineTransformRotate(t1, -90);
// Step 3
// Set the appropriate render sizes and rotational transforms
if (!self.mutableVideoComposition) {
// Create a new video composition
self.mutableVideoComposition = [AVMutableVideoComposition videoComposition];
// self.mutableVideoComposition.renderSize = CGSizeMake(assetVideoTrack.naturalSize.height,assetVideoTrack.naturalSize.width);
self.mutableVideoComposition.renderSize = CGSizeMake(finalWidth,finalHeight);
self.mutableVideoComposition.frameDuration = CMTimeMake(1,30);
// The rotate transform is set on a layer instruction
instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [self.mutableComposition duration]);
layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:(self.mutableComposition.tracks)[0]];
[layerInstruction setTransform:t2 atTime:kCMTimeZero];
} else {
self.mutableVideoComposition.renderSize = CGSizeMake(self.mutableVideoComposition.renderSize.height, self.mutableVideoComposition.renderSize.width);
// Extract the existing layer instruction on the mutableVideoComposition
instruction = (self.mutableVideoComposition.instructions)[0];
layerInstruction = (instruction.layerInstructions)[0];
// Check if a transform already exists on this layer instruction, this is done to add the current transform on top of previous edits
CGAffineTransform existingTransform;
if (![layerInstruction getTransformRampForTime:[self.mutableComposition duration] startTransform:&existingTransform endTransform:NULL timeRange:NULL]) {
[layerInstruction setTransform:t2 atTime:kCMTimeZero];
} else {
// Note: the point of origin for rotation is the upper left corner of the composition, t3 is to compensate for origin
CGAffineTransform t3 = CGAffineTransformMakeTranslation(-1*assetVideoTrack.naturalSize.height/2, 0.0);
CGAffineTransform newTransform = CGAffineTransformConcat(existingTransform, CGAffineTransformConcat(t2, t3));
[layerInstruction setTransform:newTransform atTime:kCMTimeZero];
}
}
// Step 4
// Add the transform instructions to the video composition
instruction.layerInstructions = @[layerInstruction];
self.mutableVideoComposition.instructions = @[instruction];
// Step 5
// Notify AVSEViewController about rotation operation completion
// [[NSNotificationCenter defaultCenter] postNotificationName:AVSEEditCommandCompletionNotification object:self];
[self performWithAssetExport];
}
- (void)performWithAssetExport
{
// Step 1
// Create an outputURL to which the exported movie will be saved
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *outputURL = paths[0];
NSFileManager *manager = [NSFileManager defaultManager];
[manager createDirectoryAtPath:outputURL withIntermediateDirectories:YES attributes:nil error:nil];
outputURL = [outputURL stringByAppendingPathComponent:@"output.mov"];
// Remove Existing File
[manager removeItemAtPath:outputURL error:nil];
// Step 2
// Create an export session with the composition and write the exported movie to the photo library
self.exportSession = [[AVAssetExportSession alloc] initWithAsset:[self.mutableComposition copy] presetName:AVAssetExportPreset1280x720];
self.exportSession.videoComposition = self.mutableVideoComposition;
self.exportSession.audioMix = self.mutableAudioMix;
self.exportSession.outputURL = [NSURL fileURLWithPath:outputURL];
self.exportSession.outputFileType=AVFileTypeQuickTimeMovie;
[self.exportSession exportAsynchronouslyWithCompletionHandler:^(void){
switch (self.exportSession.status) {
case AVAssetExportSessionStatusCompleted:
//[self playfunction];
[[NSNotificationCenter defaultCenter]postNotificationName:@"Backhome" object:nil];
// Step 3
// Notify AVSEViewController about export completion
break;
case AVAssetExportSessionStatusFailed:
NSLog(@"Failed:%@",self.exportSession.error);
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Canceled:%@",self.exportSession.error);
break;
default:
break;
}
}];
}