iOS AVFoundation：设置视频方向
7
- Aaron Vegh
6
2实际数据在捕获时始终具有静态方向。该方向存储在“preferredTransform”值中。因此，我猜想，您需要导出视频以旋转数据。我建议查看“AVAssetExportSession”、“AVMutableVideoComposition”、“setTransform:atTime:”功能，这可能会有所帮助。 - Davyd Geyl
我已经向苹果提交了技术支持事件请求，以帮助解决这个问题。但是像你建议的那样，我会自己看一下。这是否意味着在录制视频后需要进行单独的编码步骤呢？这可能会计算成本很高... - Aaron Vegh
是的，这将是一个额外的步骤。然而，如果在不改变原始编码的情况下进行导出，它可能并不那么昂贵。如果您找到更好的解决方案，请告诉我。 - Davyd Geyl
我已经成功地实现了您的建议——我使用了AVMutableVideoComposition创建了一个AVAssetExportSessionn，并设置了一个变换。这是一个相当棘手的过程，但我在这个周末把它搞定了。感谢您的提示！ - Aaron Vegh
太好了！我很高兴它对你起作用了。 - Davyd Geyl
大家好。现在没有任何选项可以解决我的问题（现在问题出现在FireFox和IE上，Chrome是好的）。有什么线索吗？ - Boaz
6个回答
10
最终，根据 @Aaron Vegh 和 @Prince 的回答，我找到了解决方案： // 转换视频
+(void)convertMOVToMp4:(NSString *)movFilePath completion:(void (^)(NSString *mp4FilePath))block{
AVURLAsset * videoAsset = [[AVURLAsset alloc]initWithURL:[NSURL fileURLWithPath:movFilePath] options:nil];
AVAssetTrack *sourceAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableComposition* composition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:sourceAudioTrack
atTime:kCMTimeZero error:nil];
AVAssetExportSession * assetExport = [[AVAssetExportSession alloc] initWithAsset:composition
presetName:AVAssetExportPresetMediumQuality];
NSString *exportPath = [movFilePath stringByReplacingOccurrencesOfString:@".MOV" withString:@".mp4"];
NSURL * exportUrl = [NSURL fileURLWithPath:exportPath];
assetExport.outputFileType = AVFileTypeMPEG4;
assetExport.outputURL = exportUrl;
assetExport.shouldOptimizeForNetworkUse = YES;
assetExport.videoComposition = [self getVideoComposition:videoAsset composition:composition];
[assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
switch (assetExport.status)
{
case AVAssetExportSessionStatusCompleted:
// export complete
if (block) {
block(exportPath);
}
break;
case AVAssetExportSessionStatusFailed:
block(nil);
break;
case AVAssetExportSessionStatusCancelled:
block(nil);
break;
}
}];
}
//获取当前方向
+(AVMutableVideoComposition *) getVideoComposition:(AVAsset *)asset composition:( AVMutableComposition*)composition{
BOOL isPortrait_ = [self isVideoPortrait:asset];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:videoTrack atTime:kCMTimeZero error:nil];
AVMutableVideoCompositionLayerInstruction *layerInst = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];
CGAffineTransform transform = videoTrack.preferredTransform;
[layerInst setTransform:transform atTime:kCMTimeZero];
AVMutableVideoCompositionInstruction *inst = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
inst.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);
inst.layerInstructions = [NSArray arrayWithObject:layerInst];
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
videoComposition.instructions = [NSArray arrayWithObject:inst];
CGSize videoSize = videoTrack.naturalSize;
if(isPortrait_) {
NSLog(@"video is portrait ");
videoSize = CGSizeMake(videoSize.height, videoSize.width);
}
videoComposition.renderSize = videoSize;
videoComposition.frameDuration = CMTimeMake(1,30);
videoComposition.renderScale = 1.0;
return videoComposition;
}
//获取视频
+(BOOL) isVideoPortrait:(AVAsset *)asset{
BOOL isPortrait = FALSE;
NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
if([tracks count] > 0) {
AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
CGAffineTransform t = videoTrack.preferredTransform;
// Portrait
if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0)
{
isPortrait = YES;
}
// PortraitUpsideDown
if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0) {
isPortrait = YES;
}
// LandscapeRight
if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0)
{
isPortrait = FALSE;
}
// LandscapeLeft
if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0)
{
isPortrait = FALSE;
}
}
return isPortrait;
}
- Jagie
2
嗨@Jagie，感谢提供的示例代码。我已经成功运行了它，但是当使用前置摄像头时，导出的视频只显示了一半。这意味着我需要将其沿y轴向下平移。如果我使用后置摄像头，这个问题就不存在了。你是否也遇到过前置摄像头的类似问题？ - doorman
当我尝试运行你的代码时，它给了我一个错误提示："无法合成视频。" - Hong Zhou
7
在苹果的文档中，它指出：
以下是我在设置捕获会话期间设置它的代码：
因此，Aaron Vegh发布的使用AVAssetExportSession的解决方案是可行的，但不是必需的。正如Apple文档所述，如果您想正确设置方向，以便在非Apple quicktime播放器如VLC或在Chrome上使用时播放，您必须为AVCaptureVideoDataOutput的AVCaptureConnection设置视频方向。如果您尝试为AVAssetWriterInput进行设置，则会在像VLC和Chrome这样的播放器中获得不正确的方向。在其AVCaptureVideoDataOutput -captureOutput:didOutputSampleBuffer:fromConnection:委托回调中，客户端现在可以接收物理旋转的CVPixelBuffers。在以前的iOS版本中，前置摄像头总是以AVCaptureVideoOrientationLandscapeLeft交付缓冲区，后置摄像头总是以AVCaptureVideoOrientationLandscapeRight交付缓冲区。支持所有4个AVCaptureVideoOrientations，并且旋转是硬件加速的。要请求缓冲区旋转，客户端需要在AVCaptureVideoDataOutput的视频AVCaptureConnection上调用-setVideoOrientation:。请注意，物理旋转缓冲区确实会带来性能成本，因此只有在必要时才请求旋转。例如，如果您想使用AVAssetWriter将旋转的视频写入QuickTime电影文件，则最好设置AVAssetWriterInput上的-transform属性，而不是在AVCaptureVideoDataOutput中物理旋转缓冲区。
以下是我在设置捕获会话期间设置它的代码：
// DECLARED AS PROPERTIES ABOVE
@property (strong,nonatomic) AVCaptureDeviceInput *audioIn;
@property (strong,nonatomic) AVCaptureAudioDataOutput *audioOut;
@property (strong,nonatomic) AVCaptureDeviceInput *videoIn;
@property (strong,nonatomic) AVCaptureVideoDataOutput *videoOut;
@property (strong,nonatomic) AVCaptureConnection *audioConnection;
@property (strong,nonatomic) AVCaptureConnection *videoConnection;
------------------------------------------------------------------
------------------------------------------------------------------
-(void)setupCaptureSession{
// Setup Session
self.session = [[AVCaptureSession alloc]init];
[self.session setSessionPreset:AVCaptureSessionPreset640x480];
// Create Audio connection ----------------------------------------
self.audioIn = [[AVCaptureDeviceInput alloc]initWithDevice:[self getAudioDevice] error:nil];
if ([self.session canAddInput:self.audioIn]) {
[self.session addInput:self.audioIn];
}
self.audioOut = [[AVCaptureAudioDataOutput alloc]init];
dispatch_queue_t audioCaptureQueue = dispatch_queue_create("Audio Capture Queue", DISPATCH_QUEUE_SERIAL);
[self.audioOut setSampleBufferDelegate:self queue:audioCaptureQueue];
if ([self.session canAddOutput:self.audioOut]) {
[self.session addOutput:self.audioOut];
}
self.audioConnection = [self.audioOut connectionWithMediaType:AVMediaTypeAudio];
// Create Video connection ----------------------------------------
self.videoIn = [[AVCaptureDeviceInput alloc]initWithDevice:[self videoDeviceWithPosition:AVCaptureDevicePositionBack] error:nil];
if ([self.session canAddInput:self.videoIn]) {
[self.session addInput:self.videoIn];
}
self.videoOut = [[AVCaptureVideoDataOutput alloc]init];
[self.videoOut setAlwaysDiscardsLateVideoFrames:NO];
[self.videoOut setVideoSettings:nil];
dispatch_queue_t videoCaptureQueue = dispatch_queue_create("Video Capture Queue", DISPATCH_QUEUE_SERIAL);
[self.videoOut setSampleBufferDelegate:self queue:videoCaptureQueue];
if ([self.session canAddOutput:self.videoOut]) {
[self.session addOutput:self.videoOut];
}
self.videoConnection = [self.videoOut connectionWithMediaType:AVMediaTypeVideo];
// SET THE ORIENTATION HERE -------------------------------------------------
[self.videoConnection setVideoOrientation:AVCaptureVideoOrientationPortrait];
// --------------------------------------------------------------------------
// Create Preview Layer -------------------------------------------
AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc]initWithSession:self.session];
CGRect bounds = self.videoView.bounds;
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
previewLayer.bounds = bounds;
previewLayer.position=CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds));
[self.videoView.layer addSublayer:previewLayer];
// Start session
[self.session startRunning];
}
- Kazzin
1
我很想使用这种解决方案。它可以解决很多问题。文档中提到了“性能成本”。在您的经验中，这个成本是否非常高？我对使用最高比特率的预设（例如，在 iPhone 5s 上以 120 帧每秒的 HD 分辨率）很感兴趣。 - otto
3
如果还有其他人也在寻找答案，这是我想出来的方法（经过简化修改）：
- (void)encodeVideoOrientation:(NSURL *)anOutputFileURL
{
CGAffineTransform rotationTransform;
CGAffineTransform rotateTranslate;
CGSize renderSize;
switch (self.recordingOrientation)
{
// set these 3 values based on orientation
}
AVURLAsset * videoAsset = [[AVURLAsset alloc]initWithURL:anOutputFileURL options:nil];
AVAssetTrack *sourceVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVAssetTrack *sourceAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableComposition* composition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:sourceVideoTrack
atTime:kCMTimeZero error:nil];
[compositionVideoTrack setPreferredTransform:sourceVideoTrack.preferredTransform];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:sourceAudioTrack
atTime:kCMTimeZero error:nil];
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
AVMutableVideoCompositionLayerInstruction *layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];
[layerInstruction setTransform:rotateTranslate atTime:kCMTimeZero];
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
videoComposition.frameDuration = CMTimeMake(1,30);
videoComposition.renderScale = 1.0;
videoComposition.renderSize = renderSize;
instruction.layerInstructions = [NSArray arrayWithObject: layerInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, videoAsset.duration);
videoComposition.instructions = [NSArray arrayWithObject: instruction];
AVAssetExportSession * assetExport = [[AVAssetExportSession alloc] initWithAsset:composition
presetName:AVAssetExportPresetMediumQuality];
NSString* videoName = @"export.mov";
NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:videoName];
NSURL * exportUrl = [NSURL fileURLWithPath:exportPath];
if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath])
{
[[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
}
assetExport.outputFileType = AVFileTypeMPEG4;
assetExport.outputURL = exportUrl;
assetExport.shouldOptimizeForNetworkUse = YES;
assetExport.videoComposition = videoComposition;
[assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
switch (assetExport.status)
{
case AVAssetExportSessionStatusCompleted:
// export complete
NSLog(@"Export Complete");
break;
case AVAssetExportSessionStatusFailed:
NSLog(@"Export Failed");
NSLog(@"ExportSessionError: %@", [assetExport.error localizedDescription]);
// export error (see exportSession.error)
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Export Failed");
NSLog(@"ExportSessionError: %@", [assetExport.error localizedDescription]);
// export cancelled
break;
}
}];
}
很不幸，这些东西的文档记录得很差。但是通过结合其他stackoverflow问题的示例和阅读头文件，我成功地使其工作。希望这能帮助到其他人！
- Aaron Vegh
3
使用以下方法根据视频资产的方向在AVMutableVideoComposition中设置正确的方向
-(AVMutableVideoComposition *) getVideoComposition:(AVAsset *)asset
{
AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableComposition *composition = [AVMutableComposition composition];
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
CGSize videoSize = videoTrack.naturalSize;
BOOL isPortrait_ = [self isVideoPortrait:asset];
if(isPortrait_) {
NSLog(@"video is portrait ");
videoSize = CGSizeMake(videoSize.height, videoSize.width);
}
composition.naturalSize = videoSize;
videoComposition.renderSize = videoSize;
// videoComposition.renderSize = videoTrack.naturalSize; //
videoComposition.frameDuration = CMTimeMakeWithSeconds( 1 / videoTrack.nominalFrameRate, 600);
AVMutableCompositionTrack *compositionVideoTrack;
compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:videoTrack atTime:kCMTimeZero error:nil];
AVMutableVideoCompositionLayerInstruction *layerInst;
layerInst = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
[layerInst setTransform:videoTrack.preferredTransform atTime:kCMTimeZero];
AVMutableVideoCompositionInstruction *inst = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
inst.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);
inst.layerInstructions = [NSArray arrayWithObject:layerInst];
videoComposition.instructions = [NSArray arrayWithObject:inst];
return videoComposition;
}
-(BOOL) isVideoPortrait:(AVAsset *)asset
{
BOOL isPortrait = FALSE;
NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
if([tracks count] > 0) {
AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
CGAffineTransform t = videoTrack.preferredTransform;
// Portrait
if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0)
{
isPortrait = YES;
}
// PortraitUpsideDown
if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0) {
isPortrait = YES;
}
// LandscapeRight
if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0)
{
isPortrait = FALSE;
}
// LandscapeLeft
if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0)
{
isPortrait = FALSE;
}
}
return isPortrait;
}
- Paresh Navadiya
1
如果有人对资产的
naturalSize感到困惑，可以使用这个示例中的isVideoPortrait方法，它会解决问题。谢谢Paresh！ - undefined1
iOS 5以后，您可以使用AVCaptureVideoDataOutput（在此处记录）请求旋转的CVPixelBuffers。这样可以获得正确的方向，而无需使用AVAssetExportSession重新处理视频。
- CEarwood
0
这是@Jagie代码的最新Swift版本。
extension AVURLAsset
{
func exportVideo(presetName: String = AVAssetExportPresetHighestQuality, outputFileType: AVFileType = .mp4, fileExtension: String = "mp4", then completion: @escaping (URL?) -> Void)
{
let filename = url.deletingPathExtension().appendingPathExtension(fileExtension).lastPathComponent
let outputURL = FileManager.default.temporaryDirectory.appendingPathComponent(filename)
do { // delete old video, if already exists
try FileManager.default.removeItem(at: outputURL)
} catch {
print(error.localizedDescription)
}
guard let sourceAudioTrack = self.tracks(withMediaType: .audio).first else { return }
let composition = AVMutableComposition()
let compositionAudioTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)
do{
try compositionAudioTrack?.insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: self.duration), of: sourceAudioTrack, at: CMTime.zero)
}catch(let e){
print("error: \(e)")
}
if let session = AVAssetExportSession(asset: composition, presetName: presetName) {
session.outputURL = outputURL
session.outputFileType = outputFileType
let start = CMTimeMakeWithSeconds(0.0, preferredTimescale: 0)
let range = CMTimeRangeMake(start: start, duration: duration)
session.timeRange = range
session.shouldOptimizeForNetworkUse = true
session.videoComposition = getVideoComposition(asset: self, composition: composition)
session.exportAsynchronously {
switch session.status {
case .completed:
completion(outputURL)
case .cancelled:
debugPrint("Video export cancelled.")
completion(nil)
case .failed:
let errorMessage = session.error?.localizedDescription ?? "n/a"
debugPrint("Video export failed with error: \(errorMessage)")
completion(nil)
default:
break
}
}
} else {
completion(nil)
}
}
private func getVideoComposition(asset: AVAsset, composition: AVMutableComposition) -> AVMutableVideoComposition{
let isPortrait = isVideoPortrait()
let compositionVideoTrack: AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: .video, preferredTrackID:kCMPersistentTrackID_Invalid)!
let videoTrack:AVAssetTrack = asset.tracks(withMediaType: .video).first!
do{
try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: asset.duration), of: videoTrack, at: CMTime.zero)
}catch(let e){
print("Error: \(e)")
}
let layerInst:AVMutableVideoCompositionLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: compositionVideoTrack)
let transform = videoTrack.preferredTransform
layerInst.setTransform(transform, at: CMTime.zero)
let inst:AVMutableVideoCompositionInstruction = AVMutableVideoCompositionInstruction()
inst.timeRange = CMTimeRangeMake(start: CMTime.zero, duration: asset.duration);
inst.layerInstructions = [layerInst]
let videoComposition: AVMutableVideoComposition = AVMutableVideoComposition()
videoComposition.instructions = [inst]
var videoSize:CGSize = videoTrack.naturalSize;
if(isPortrait) {
print("video is portrait")
videoSize = CGSize(width: videoSize.height, height: videoSize.width)
}else{
print("video is landscape")
}
videoComposition.renderSize = videoSize;
videoComposition.frameDuration = CMTimeMake(value: 1,timescale: 30);
videoComposition.renderScale = 1.0;
return videoComposition;
}
func isVideoPortrait() -> Bool{
var isPortrait = false
let tracks = self.tracks(withMediaType: .video)
if(tracks.count > 0) {
let videoTrack:AVAssetTrack = tracks.first!;
let t:CGAffineTransform = videoTrack.preferredTransform;
// Portrait
if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0)
{
isPortrait = true;
}
// PortraitUpsideDown
if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0) {
isPortrait = true;
}
// LandscapeRight
if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0)
{
isPortrait = false;
}
// LandscapeLeft
if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0)
{
isPortrait = false;
}
}
return isPortrait;
}
}
- virtplay
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