我有一个严重的问题：我有一个包含多个UIImage对象的NSArray。现在我想做的是从这些UIImages创建电影。但我不知道如何实现。
希望有人能帮助我或者发送给我一段能够实现我的需求的代码片段。
编辑：供后来者参考 - 在应用解决方案后，如果视频看起来扭曲，请确保捕获图像/区域的宽度是16的倍数。在此处长时间挣扎后发现：
为什么我的来自UIImages的电影会出现扭曲？
这里是完整的解决方案（只需确保宽度是16的倍数）
http://codethink.no-ip.org/wordpress/archives/673
请查看AVAssetWriter和AVFoundation框架的其他内容。该写入器具有类型为AVAssetWriterInput的输入，该输入又有一个名为appendSampleBuffer:的方法，可让您向视频流添加单个帧。基本上，您需要：
1）连接写入器：
NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
[NSURL fileURLWithPath:somePath] fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(videoWriter);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:640], AVVideoWidthKey,
[NSNumber numberWithInt:480], AVVideoHeightKey,
nil];
AVAssetWriterInput* writerInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain]; //retain should be removed if ARC
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
2) 开始会话：
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:…] //use kCMTimeZero if unsure
3) 写一些示例：
// Or you can use AVAssetWriterInputPixelBufferAdaptor.
// That lets you feed the writer input data from a CVPixelBuffer
// that’s quite easy to create from a CGImage.
[writerInput appendSampleBuffer:sampleBuffer];
4) 结束会话：
[writerInput markAsFinished];
[videoWriter endSessionAtSourceTime:…]; //optional can call finishWriting without specifying endTime
[videoWriter finishWriting]; //deprecated in ios6
/*
[videoWriter finishWritingWithCompletionHandler:...]; //ios 6.0+
*/
你仍然需要填写很多空白，但我认为唯一剩下的真正困难的部分是从CGImage中获取像素缓冲区：
- (CVPixelBufferRef) newPixelBufferFromCGImage: (CGImageRef) image
{
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
frameSize.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, frameSize.width,
frameSize.height, 8, 4*frameSize.width, rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
CGContextConcatCTM(context, frameTransform);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
frameSize 是一个 CGSize，描述了目标帧的大小，frameTransform 是一个 CGAffineTransform，允许你在绘制图像到帧时对它们进行变换。
CGImage 中，然后再将其绘制到由 CVPixelBuffer 支持的 CGBitmapContext 中是浪费资源的。同样地，不应每次创建一个 CVPixelBuffer，而应使用 AVAssetWriterInputPixelBufferAdaptor 的 pixelBufferPool 来回收缓冲区。 - rpetrichappendSampleBuffer: 的参数类型不是 CMSampleBufferRef 吗？顺便说一下，我在 OS X 中使用 AVFoundation。 - Andrew Chang上周我开始编写iOS代码，用于从图像生成视频。我有一点AVFoundation经验，但从未听说过CVPixelBuffer。我在这个页面和这里找到了答案。花费了几天时间来剖析所有内容，并以一种对我有意义的方式在Swift中重新组合它们。以下是我的成果。
注意：如果您将下面的所有代码复制/粘贴到一个Swift文件中，它应该可以编译。您只需要调整loadImages()和RenderSettings值。
在这里，我将所有与导出相关的设置都分组到一个名为RenderSettings的结构体中。
import AVFoundation
import UIKit
import Photos
struct RenderSettings {
var size : CGSize = .zero
var fps: Int32 = 6 // frames per second
var avCodecKey = AVVideoCodecType.h264
var videoFilename = "render"
var videoFilenameExt = "mp4"
var outputURL: URL {
// Use the CachesDirectory so the rendered video file sticks around as long as we need it to.
// Using the CachesDirectory ensures the file won't be included in a backup of the app.
let fileManager = FileManager.default
if let tmpDirURL = try? fileManager.url(for: .cachesDirectory, in: .userDomainMask, appropriateFor: nil, create: true) {
return tmpDirURL.appendingPathComponent(videoFilename).appendingPathExtension(videoFilenameExt)
}
fatalError("URLForDirectory() failed")
}
ImageAnimator类了解您的图像并使用VideoWriter类执行渲染。其思想是将视频内容代码与低级AVFoundation代码分开。我还在这里添加了saveToLibrary()作为一个类函数，该函数在链的末尾被调用以将视频保存到照片库中。
class ImageAnimator {
// Apple suggests a timescale of 600 because it's a multiple of standard video rates 24, 25, 30, 60 fps etc.
static let kTimescale: Int32 = 600
let settings: RenderSettings
let videoWriter: VideoWriter
var images: [UIImage]!
var frameNum = 0
class func saveToLibrary(videoURL: URL) {
PHPhotoLibrary.requestAuthorization { status in
guard status == .authorized else { return }
PHPhotoLibrary.shared().performChanges({
PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: videoURL)
}) { success, error in
if !success {
print("Could not save video to photo library:", error)
}
}
}
}
class func removeFileAtURL(fileURL: URL) {
do {
try FileManager.default.removeItem(atPath: fileURL.path)
}
catch _ as NSError {
// Assume file doesn't exist.
}
}
init(renderSettings: RenderSettings) {
settings = renderSettings
videoWriter = VideoWriter(renderSettings: settings)
//images = loadImages()
}
func render(completion: (()->Void)?) {
// The VideoWriter will fail if a file exists at the URL, so clear it out first.
ImageAnimator.removeFileAtURL(fileURL: settings.outputURL)
videoWriter.start()
videoWriter.render(appendPixelBuffers: appendPixelBuffers) {
ImageAnimator.saveToLibrary(videoURL: self.settings.outputURL)
completion?()
}
}
// This is the callback function for VideoWriter.render()
func appendPixelBuffers(writer: VideoWriter) -> Bool {
let frameDuration = CMTimeMake(value: Int64(ImageAnimator.kTimescale / settings.fps), timescale: ImageAnimator.kTimescale)
while !images.isEmpty {
if writer.isReadyForData == false {
// Inform writer we have more buffers to write.
return false
}
let image = images.removeFirst()
let presentationTime = CMTimeMultiply(frameDuration, multiplier: Int32(frameNum))
let success = videoWriter.addImage(image: image, withPresentationTime: presentationTime)
if success == false {
fatalError("addImage() failed")
}
frameNum += 1
}
// Inform writer all buffers have been written.
return true
}
VideoWriter类完成了所有AVFoundation的重活。它主要是AVAssetWriter和AVAssetWriterInput的包装器。它还包含不是我编写的精美代码，知道如何将图像转换为CVPixelBuffer。
class VideoWriter {
let renderSettings: RenderSettings
var videoWriter: AVAssetWriter!
var videoWriterInput: AVAssetWriterInput!
var pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor!
var isReadyForData: Bool {
return videoWriterInput?.isReadyForMoreMediaData ?? false
}
class func pixelBufferFromImage(image: UIImage, pixelBufferPool: CVPixelBufferPool, size: CGSize) -> CVPixelBuffer {
var pixelBufferOut: CVPixelBuffer?
let status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pixelBufferOut)
if status != kCVReturnSuccess {
fatalError("CVPixelBufferPoolCreatePixelBuffer() failed")
}
let pixelBuffer = pixelBufferOut!
CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
let data = CVPixelBufferGetBaseAddress(pixelBuffer)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(data: data, width: Int(size.width), height: Int(size.height),
bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue)
context!.clear(CGRect(x:0,y: 0,width: size.width,height: size.height))
let horizontalRatio = size.width / image.size.width
let verticalRatio = size.height / image.size.height
//aspectRatio = max(horizontalRatio, verticalRatio) // ScaleAspectFill
let aspectRatio = min(horizontalRatio, verticalRatio) // ScaleAspectFit
let newSize = CGSize(width: image.size.width * aspectRatio, height: image.size.height * aspectRatio)
let x = newSize.width < size.width ? (size.width - newSize.width) / 2 : 0
let y = newSize.height < size.height ? (size.height - newSize.height) / 2 : 0
context?.draw(image.cgImage!, in: CGRect(x:x,y: y, width: newSize.width, height: newSize.height))
CVPixelBufferUnlockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
return pixelBuffer
}
init(renderSettings: RenderSettings) {
self.renderSettings = renderSettings
}
func start() {
let avOutputSettings: [String: Any] = [
AVVideoCodecKey: renderSettings.avCodecKey,
AVVideoWidthKey: NSNumber(value: Float(renderSettings.size.width)),
AVVideoHeightKey: NSNumber(value: Float(renderSettings.size.height))
]
func createPixelBufferAdaptor() {
let sourcePixelBufferAttributesDictionary = [
kCVPixelBufferPixelFormatTypeKey as String: NSNumber(value: kCVPixelFormatType_32ARGB),
kCVPixelBufferWidthKey as String: NSNumber(value: Float(renderSettings.size.width)),
kCVPixelBufferHeightKey as String: NSNumber(value: Float(renderSettings.size.height))
]
pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput,
sourcePixelBufferAttributes: sourcePixelBufferAttributesDictionary)
}
func createAssetWriter(outputURL: URL) -> AVAssetWriter {
guard let assetWriter = try? AVAssetWriter(outputURL: outputURL, fileType: AVFileType.mp4) else {
fatalError("AVAssetWriter() failed")
}
guard assetWriter.canApply(outputSettings: avOutputSettings, forMediaType: AVMediaType.video) else {
fatalError("canApplyOutputSettings() failed")
}
return assetWriter
}
videoWriter = createAssetWriter(outputURL: renderSettings.outputURL)
videoWriterInput = AVAssetWriterInput(mediaType: AVMediaType.video, outputSettings: avOutputSettings)
if videoWriter.canAdd(videoWriterInput) {
videoWriter.add(videoWriterInput)
}
else {
fatalError("canAddInput() returned false")
}
// The pixel buffer adaptor must be created before we start writing.
createPixelBufferAdaptor()
if videoWriter.startWriting() == false {
fatalError("startWriting() failed")
}
videoWriter.startSession(atSourceTime: CMTime.zero)
precondition(pixelBufferAdaptor.pixelBufferPool != nil, "nil pixelBufferPool")
}
func render(appendPixelBuffers: ((VideoWriter)->Bool)?, completion: (()->Void)?) {
precondition(videoWriter != nil, "Call start() to initialze the writer")
let queue = DispatchQueue(label: "mediaInputQueue")
videoWriterInput.requestMediaDataWhenReady(on: queue) {
let isFinished = appendPixelBuffers?(self) ?? false
if isFinished {
self.videoWriterInput.markAsFinished()
self.videoWriter.finishWriting() {
DispatchQueue.main.async {
completion?()
}
}
}
else {
// Fall through. The closure will be called again when the writer is ready.
}
}
}
func addImage(image: UIImage, withPresentationTime presentationTime: CMTime) -> Bool {
precondition(pixelBufferAdaptor != nil, "Call start() to initialze the writer")
let pixelBuffer = VideoWriter.pixelBufferFromImage(image: image, pixelBufferPool: pixelBufferAdaptor.pixelBufferPool!, size: renderSettings.size)
return pixelBufferAdaptor.append(pixelBuffer, withPresentationTime: presentationTime)
}
一旦所有准备工作就绪，这是你的三条魔法语句：
let settings = RenderSettings()
let imageAnimator = ImageAnimator(renderSettings: settings)
imageAnimator.render() {
print("yes")
}
images = [image, image] 可以工作，但单个图像不行。
假设我将时间更改为10秒，那么我会看到一个黑屏，直到最后一帧。非常奇怪。 - impression7vxfatalError("canApplyOutputSettings() failed") 这一行出错了（iOS 11，Swift 4）。有没有修复的方法？ - LinusGeffarthfatalError("canApplyOutputSettings() failed") 错误，您需要将 RenderSettings 的 size 值设置为除了 .zero 以外的其他值。 - oneyenjug以下是在Objective-C中针对iOS8的最新可用代码。
我们需要对 @Zoul 在上面的回答进行各种调整，才能使其在最新版本的Xcode和iOS8上正常工作。这是我们完整的工作代码，它将一个UIImage数组转换为.mov文件，将其保存到临时目录，然后移动到相机胶卷。我们从多个不同的帖子中组合了代码以使其正常工作。我们在注释中突出显示了我们必须解决的陷阱。
（1）创建一个UIImage的集合
[self saveMovieToLibrary]
- (IBAction)saveMovieToLibrary
{
// You just need the height and width of the video here
// For us, our input and output video was 640 height x 480 width
// which is what we get from the iOS front camera
ATHSingleton *singleton = [ATHSingleton singletons];
int height = singleton.screenHeight;
int width = singleton.screenWidth;
// You can save a .mov or a .mp4 file
//NSString *fileNameOut = @"temp.mp4";
NSString *fileNameOut = @"temp.mov";
// We chose to save in the tmp/ directory on the device initially
NSString *directoryOut = @"tmp/";
NSString *outFile = [NSString stringWithFormat:@"%@%@",directoryOut,fileNameOut];
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:outFile]];
NSURL *videoTempURL = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@%@", NSTemporaryDirectory(), fileNameOut]];
// WARNING: AVAssetWriter does not overwrite files for us, so remove the destination file if it already exists
NSFileManager *fileManager = [NSFileManager defaultManager];
[fileManager removeItemAtPath:[videoTempURL path] error:NULL];
// Create your own array of UIImages
NSMutableArray *images = [NSMutableArray array];
for (int i=0; i<singleton.numberOfScreenshots; i++)
{
// This was our routine that returned a UIImage. Just use your own.
UIImage *image =[self uiimageFromCopyOfPixelBuffersUsingIndex:i];
// We used a routine to write text onto every image
// so we could validate the images were actually being written when testing. This was it below.
image = [self writeToImage:image Text:[NSString stringWithFormat:@"%i",i ]];
[images addObject:image];
}
// If you just want to manually add a few images - here is code you can uncomment
// NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/movie.mp4"]];
// NSArray *images = [[NSArray alloc] initWithObjects:
// [UIImage imageNamed:@"add_ar.png"],
// [UIImage imageNamed:@"add_ja.png"],
// [UIImage imageNamed:@"add_ru.png"],
// [UIImage imageNamed:@"add_ru.png"],
// [UIImage imageNamed:@"add_ar.png"],
// [UIImage imageNamed:@"add_ja.png"],
// [UIImage imageNamed:@"add_ru.png"],
// [UIImage imageNamed:@"add_ar.png"],
// [UIImage imageNamed:@"add_en.png"], nil];
[self writeImageAsMovie:images toPath:path size:CGSizeMake(height, width)];
}
这是创建AssetWriter并将图像添加到其中进行写入的主要方法。
(2) 配置 AVAssetWriter
-(void)writeImageAsMovie:(NSArray *)array toPath:(NSString*)path size:(CGSize)size
{
NSError *error = nil;
// FIRST, start up an AVAssetWriter instance to write your video
// Give it a destination path (for us: tmp/temp.mov)
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:path]
fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(videoWriter);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey,
nil];
AVAssetWriterInput* writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:nil];
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
（3）开始写作会话（注意：该方法是从上面继续进行的）
//Start a SESSION of writing.
// After you start a session, you will keep adding image frames
// until you are complete - then you will tell it you are done.
[videoWriter startWriting];
// This starts your video at time = 0
[videoWriter startSessionAtSourceTime:kCMTimeZero];
CVPixelBufferRef buffer = NULL;
// This was just our utility class to get screen sizes etc.
ATHSingleton *singleton = [ATHSingleton singletons];
int i = 0;
while (1)
{
// Check if the writer is ready for more data, if not, just wait
if(writerInput.readyForMoreMediaData){
CMTime frameTime = CMTimeMake(150, 600);
// CMTime = Value and Timescale.
// Timescale = the number of tics per second you want
// Value is the number of tics
// For us - each frame we add will be 1/4th of a second
// Apple recommend 600 tics per second for video because it is a
// multiple of the standard video rates 24, 30, 60 fps etc.
CMTime lastTime=CMTimeMake(i*150, 600);
CMTime presentTime=CMTimeAdd(lastTime, frameTime);
if (i == 0) {presentTime = CMTimeMake(0, 600);}
// This ensures the first frame starts at 0.
if (i >= [array count])
{
buffer = NULL;
}
else
{
// This command grabs the next UIImage and converts it to a CGImage
buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:i] CGImage]];
}
if (buffer)
{
// Give the CGImage to the AVAssetWriter to add to your video
[adaptor appendPixelBuffer:buffer withPresentationTime:presentTime];
i++;
}
else
{
（4）结束会话（注意：本方法继续自上文）
//Finish the session:
// This is important to be done exactly in this order
[writerInput markAsFinished];
// WARNING: finishWriting in the solution above is deprecated.
// You now need to give a completion handler.
[videoWriter finishWritingWithCompletionHandler:^{
NSLog(@"Finished writing...checking completion status...");
if (videoWriter.status != AVAssetWriterStatusFailed && videoWriter.status == AVAssetWriterStatusCompleted)
{
NSLog(@"Video writing succeeded.");
// Move video to camera roll
// NOTE: You cannot write directly to the camera roll.
// You must first write to an iOS directory then move it!
NSURL *videoTempURL = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@", path]];
[self saveToCameraRoll:videoTempURL];
} else
{
NSLog(@"Video writing failed: %@", videoWriter.error);
}
}]; // end videoWriter finishWriting Block
CVPixelBufferPoolRelease(adaptor.pixelBufferPool);
NSLog (@"Done");
break;
}
}
}
}
(5) 将您的UIImages转换为CVPixelBufferRef
使用此方法将为您提供CV像素缓冲区引用，这是AssetWriter所需的。这是从CGImageRef获得的，而CGImageRef可以从您的UIImage（上面）获取。
- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image
{
// This again was just our utility class for the height & width of the
// incoming video (640 height x 480 width)
ATHSingleton *singleton = [ATHSingleton singletons];
int height = singleton.screenHeight;
int width = singleton.screenWidth;
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, width,
height, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, width,
height, 8, 4*width, rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
(6) 将视频移动到相机胶卷 由于AVAssetWriter无法直接写入相机胶卷，因此需要将视频从“tmp/temp.mov”（或您在上面命名的任何文件名）移动到相机胶卷。
- (void) saveToCameraRoll:(NSURL *)srcURL
{
NSLog(@"srcURL: %@", srcURL);
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
ALAssetsLibraryWriteVideoCompletionBlock videoWriteCompletionBlock =
^(NSURL *newURL, NSError *error) {
if (error) {
NSLog( @"Error writing image with metadata to Photo Library: %@", error );
} else {
NSLog( @"Wrote image with metadata to Photo Library %@", newURL.absoluteString);
}
};
if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:srcURL])
{
[library writeVideoAtPathToSavedPhotosAlbum:srcURL
completionBlock:videoWriteCompletionBlock];
}
}
Zoul的回答上面提供了你将要做的事情的良好概述。我们在这段代码中进行了广泛的注释，因此您可以看到如何使用可工作的代码完成它。
我采用了Zoul的主要思路，并结合了AVAssetWriterInputPixelBufferAdaptor方法，制作了一个小框架的雏形。
欢迎查看并改进！CEMovieMaker
这是在iOS 8上测试过的Swift 2.x版本，结合了@Scott Raposa和@Praxiteles的答案以及@acj为另一个问题贡献的代码。来自@acj的代码在这里：https://gist.github.com/acj/6ae90aa1ebb8cad6b47b。@TimBull也提供了代码。
像@Scott Raposa一样，我从未听说过CVPixelBufferPoolCreatePixelBuffer和其他几个函数，更不用说如何使用它们了。
下面的内容主要是通过试验和阅读苹果文档拼凑而成。请谨慎使用，并在有错误时提供建议。
使用方法：
import UIKit
import AVFoundation
import Photos
writeImagesAsMovie(yourImages, videoPath: yourPath, videoSize: yourSize, videoFPS: 30)
代码：
func writeImagesAsMovie(allImages: [UIImage], videoPath: String, videoSize: CGSize, videoFPS: Int32) {
// Create AVAssetWriter to write video
guard let assetWriter = createAssetWriter(videoPath, size: videoSize) else {
print("Error converting images to video: AVAssetWriter not created")
return
}
// If here, AVAssetWriter exists so create AVAssetWriterInputPixelBufferAdaptor
let writerInput = assetWriter.inputs.filter{ $0.mediaType == AVMediaTypeVideo }.first!
let sourceBufferAttributes : [String : AnyObject] = [
kCVPixelBufferPixelFormatTypeKey as String : Int(kCVPixelFormatType_32ARGB),
kCVPixelBufferWidthKey as String : videoSize.width,
kCVPixelBufferHeightKey as String : videoSize.height,
]
let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: writerInput, sourcePixelBufferAttributes: sourceBufferAttributes)
// Start writing session
assetWriter.startWriting()
assetWriter.startSessionAtSourceTime(kCMTimeZero)
if (pixelBufferAdaptor.pixelBufferPool == nil) {
print("Error converting images to video: pixelBufferPool nil after starting session")
return
}
// -- Create queue for <requestMediaDataWhenReadyOnQueue>
let mediaQueue = dispatch_queue_create("mediaInputQueue", nil)
// -- Set video parameters
let frameDuration = CMTimeMake(1, videoFPS)
var frameCount = 0
// -- Add images to video
let numImages = allImages.count
writerInput.requestMediaDataWhenReadyOnQueue(mediaQueue, usingBlock: { () -> Void in
// Append unadded images to video but only while input ready
while (writerInput.readyForMoreMediaData && frameCount < numImages) {
let lastFrameTime = CMTimeMake(Int64(frameCount), videoFPS)
let presentationTime = frameCount == 0 ? lastFrameTime : CMTimeAdd(lastFrameTime, frameDuration)
if !self.appendPixelBufferForImageAtURL(allImages[frameCount], pixelBufferAdaptor: pixelBufferAdaptor, presentationTime: presentationTime) {
print("Error converting images to video: AVAssetWriterInputPixelBufferAdapter failed to append pixel buffer")
return
}
frameCount += 1
}
// No more images to add? End video.
if (frameCount >= numImages) {
writerInput.markAsFinished()
assetWriter.finishWritingWithCompletionHandler {
if (assetWriter.error != nil) {
print("Error converting images to video: \(assetWriter.error)")
} else {
self.saveVideoToLibrary(NSURL(fileURLWithPath: videoPath))
print("Converted images to movie @ \(videoPath)")
}
}
}
})
}
func createAssetWriter(path: String, size: CGSize) -> AVAssetWriter? {
// Convert <path> to NSURL object
let pathURL = NSURL(fileURLWithPath: path)
// Return new asset writer or nil
do {
// Create asset writer
let newWriter = try AVAssetWriter(URL: pathURL, fileType: AVFileTypeMPEG4)
// Define settings for video input
let videoSettings: [String : AnyObject] = [
AVVideoCodecKey : AVVideoCodecH264,
AVVideoWidthKey : size.width,
AVVideoHeightKey : size.height,
]
// Add video input to writer
let assetWriterVideoInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: videoSettings)
newWriter.addInput(assetWriterVideoInput)
// Return writer
print("Created asset writer for \(size.width)x\(size.height) video")
return newWriter
} catch {
print("Error creating asset writer: \(error)")
return nil
}
}
func appendPixelBufferForImageAtURL(image: UIImage, pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor, presentationTime: CMTime) -> Bool {
var appendSucceeded = false
autoreleasepool {
if let pixelBufferPool = pixelBufferAdaptor.pixelBufferPool {
let pixelBufferPointer = UnsafeMutablePointer<CVPixelBuffer?>.alloc(1)
let status: CVReturn = CVPixelBufferPoolCreatePixelBuffer(
kCFAllocatorDefault,
pixelBufferPool,
pixelBufferPointer
)
if let pixelBuffer = pixelBufferPointer.memory where status == 0 {
fillPixelBufferFromImage(image, pixelBuffer: pixelBuffer)
appendSucceeded = pixelBufferAdaptor.appendPixelBuffer(pixelBuffer, withPresentationTime: presentationTime)
pixelBufferPointer.destroy()
} else {
NSLog("Error: Failed to allocate pixel buffer from pool")
}
pixelBufferPointer.dealloc(1)
}
}
return appendSucceeded
}
func fillPixelBufferFromImage(image: UIImage, pixelBuffer: CVPixelBufferRef) {
CVPixelBufferLockBaseAddress(pixelBuffer, 0)
let pixelData = CVPixelBufferGetBaseAddress(pixelBuffer)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
// Create CGBitmapContext
let context = CGBitmapContextCreate(
pixelData,
Int(image.size.width),
Int(image.size.height),
8,
CVPixelBufferGetBytesPerRow(pixelBuffer),
rgbColorSpace,
CGImageAlphaInfo.PremultipliedFirst.rawValue
)
// Draw image into context
CGContextDrawImage(context, CGRectMake(0, 0, image.size.width, image.size.height), image.CGImage)
CVPixelBufferUnlockBaseAddress(pixelBuffer, 0)
}
func saveVideoToLibrary(videoURL: NSURL) {
PHPhotoLibrary.requestAuthorization { status in
// Return if unauthorized
guard status == .Authorized else {
print("Error saving video: unauthorized access")
return
}
// If here, save video to library
PHPhotoLibrary.sharedPhotoLibrary().performChanges({
PHAssetChangeRequest.creationRequestForAssetFromVideoAtFileURL(videoURL)
}) { success, error in
if !success {
print("Error saving video: \(error)")
}
}
}
}
我把@Scott Raposa的答案翻译成了Swift 3（稍微做了一点修改）：
import AVFoundation
import UIKit
import Photos
struct RenderSettings {
var size : CGSize = .zero
var fps: Int32 = 6 // frames per second
var avCodecKey = AVVideoCodecH264
var videoFilename = "render"
var videoFilenameExt = "mp4"
var outputURL: URL {
// Use the CachesDirectory so the rendered video file sticks around as long as we need it to.
// Using the CachesDirectory ensures the file won't be included in a backup of the app.
let fileManager = FileManager.default
if let tmpDirURL = try? fileManager.url(for: .cachesDirectory, in: .userDomainMask, appropriateFor: nil, create: true) {
return tmpDirURL.appendingPathComponent(videoFilename).appendingPathExtension(videoFilenameExt)
}
fatalError("URLForDirectory() failed")
}
}
class ImageAnimator {
// Apple suggests a timescale of 600 because it's a multiple of standard video rates 24, 25, 30, 60 fps etc.
static let kTimescale: Int32 = 600
let settings: RenderSettings
let videoWriter: VideoWriter
var images: [UIImage]!
var frameNum = 0
class func saveToLibrary(videoURL: URL) {
PHPhotoLibrary.requestAuthorization { status in
guard status == .authorized else { return }
PHPhotoLibrary.shared().performChanges({
PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: videoURL)
}) { success, error in
if !success {
print("Could not save video to photo library:", error)
}
}
}
}
class func removeFileAtURL(fileURL: URL) {
do {
try FileManager.default.removeItem(atPath: fileURL.path)
}
catch _ as NSError {
// Assume file doesn't exist.
}
}
init(renderSettings: RenderSettings) {
settings = renderSettings
videoWriter = VideoWriter(renderSettings: settings)
// images = loadImages()
}
func render(completion: (()->Void)?) {
// The VideoWriter will fail if a file exists at the URL, so clear it out first.
ImageAnimator.removeFileAtURL(fileURL: settings.outputURL)
videoWriter.start()
videoWriter.render(appendPixelBuffers: appendPixelBuffers) {
ImageAnimator.saveToLibrary(videoURL: self.settings.outputURL)
completion?()
}
}
// // Replace this logic with your own.
// func loadImages() -> [UIImage] {
// var images = [UIImage]()
// for index in 1...10 {
// let filename = "\(index).jpg"
// images.append(UIImage(named: filename)!)
// }
// return images
// }
// This is the callback function for VideoWriter.render()
func appendPixelBuffers(writer: VideoWriter) -> Bool {
let frameDuration = CMTimeMake(Int64(ImageAnimator.kTimescale / settings.fps), ImageAnimator.kTimescale)
while !images.isEmpty {
if writer.isReadyForData == false {
// Inform writer we have more buffers to write.
return false
}
let image = images.removeFirst()
let presentationTime = CMTimeMultiply(frameDuration, Int32(frameNum))
let success = videoWriter.addImage(image: image, withPresentationTime: presentationTime)
if success == false {
fatalError("addImage() failed")
}
frameNum += 1
}
// Inform writer all buffers have been written.
return true
}
}
class VideoWriter {
let renderSettings: RenderSettings
var videoWriter: AVAssetWriter!
var videoWriterInput: AVAssetWriterInput!
var pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor!
var isReadyForData: Bool {
return videoWriterInput?.isReadyForMoreMediaData ?? false
}
class func pixelBufferFromImage(image: UIImage, pixelBufferPool: CVPixelBufferPool, size: CGSize) -> CVPixelBuffer {
var pixelBufferOut: CVPixelBuffer?
let status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pixelBufferOut)
if status != kCVReturnSuccess {
fatalError("CVPixelBufferPoolCreatePixelBuffer() failed")
}
let pixelBuffer = pixelBufferOut!
CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
let data = CVPixelBufferGetBaseAddress(pixelBuffer)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(data: data, width: Int(size.width), height: Int(size.height),
bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue)
context!.clear(CGRect(x:0,y: 0,width: size.width,height: size.height))
let horizontalRatio = size.width / image.size.width
let verticalRatio = size.height / image.size.height
//aspectRatio = max(horizontalRatio, verticalRatio) // ScaleAspectFill
let aspectRatio = min(horizontalRatio, verticalRatio) // ScaleAspectFit
let newSize = CGSize(width: image.size.width * aspectRatio, height: image.size.height * aspectRatio)
let x = newSize.width < size.width ? (size.width - newSize.width) / 2 : 0
let y = newSize.height < size.height ? (size.height - newSize.height) / 2 : 0
context?.draw(image.cgImage!, in: CGRect(x:x,y: y, width: newSize.width, height: newSize.height))
CVPixelBufferUnlockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
return pixelBuffer
}
init(renderSettings: RenderSettings) {
self.renderSettings = renderSettings
}
func start() {
let avOutputSettings: [String: Any] = [
AVVideoCodecKey: renderSettings.avCodecKey,
AVVideoWidthKey: NSNumber(value: Float(renderSettings.size.width)),
AVVideoHeightKey: NSNumber(value: Float(renderSettings.size.height))
]
func createPixelBufferAdaptor() {
let sourcePixelBufferAttributesDictionary = [
kCVPixelBufferPixelFormatTypeKey as String: NSNumber(value: kCVPixelFormatType_32ARGB),
kCVPixelBufferWidthKey as String: NSNumber(value: Float(renderSettings.size.width)),
kCVPixelBufferHeightKey as String: NSNumber(value: Float(renderSettings.size.height))
]
pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput,
sourcePixelBufferAttributes: sourcePixelBufferAttributesDictionary)
}
func createAssetWriter(outputURL: URL) -> AVAssetWriter {
guard let assetWriter = try? AVAssetWriter(outputURL: outputURL, fileType: AVFileTypeMPEG4) else {
fatalError("AVAssetWriter() failed")
}
guard assetWriter.canApply(outputSettings: avOutputSettings, forMediaType: AVMediaTypeVideo) else {
fatalError("canApplyOutputSettings() failed")
}
return assetWriter
}
videoWriter = createAssetWriter(outputURL: renderSettings.outputURL)
videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: avOutputSettings)
if videoWriter.canAdd(videoWriterInput) {
videoWriter.add(videoWriterInput)
}
else {
fatalError("canAddInput() returned false")
}
// The pixel buffer adaptor must be created before we start writing.
createPixelBufferAdaptor()
if videoWriter.startWriting() == false {
fatalError("startWriting() failed")
}
videoWriter.startSession(atSourceTime: kCMTimeZero)
precondition(pixelBufferAdaptor.pixelBufferPool != nil, "nil pixelBufferPool")
}
func render(appendPixelBuffers: ((VideoWriter)->Bool)?, completion: (()->Void)?) {
precondition(videoWriter != nil, "Call start() to initialze the writer")
let queue = DispatchQueue(label: "mediaInputQueue")
videoWriterInput.requestMediaDataWhenReady(on: queue) {
let isFinished = appendPixelBuffers?(self) ?? false
if isFinished {
self.videoWriterInput.markAsFinished()
self.videoWriter.finishWriting() {
DispatchQueue.main.async {
completion?()
}
}
}
else {
// Fall through. The closure will be called again when the writer is ready.
}
}
}
func addImage(image: UIImage, withPresentationTime presentationTime: CMTime) -> Bool {
precondition(pixelBufferAdaptor != nil, "Call start() to initialze the writer")
let pixelBuffer = VideoWriter.pixelBufferFromImage(image: image, pixelBufferPool: pixelBufferAdaptor.pixelBufferPool!, size: renderSettings.size)
return pixelBufferAdaptor.append(pixelBuffer, withPresentationTime: presentationTime)
}
}
以下是将图片数组转换为视频的Swift3版本：
import Foundation
import AVFoundation
import UIKit
typealias CXEMovieMakerCompletion = (URL) -> Void
typealias CXEMovieMakerUIImageExtractor = (AnyObject) -> UIImage?
public class ImagesToVideoUtils: NSObject {
static let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
static let tempPath = paths[0] + "/exprotvideo.mp4"
static let fileURL = URL(fileURLWithPath: tempPath)
// static let tempPath = NSTemporaryDirectory() + "/exprotvideo.mp4"
// static let fileURL = URL(fileURLWithPath: tempPath)
var assetWriter:AVAssetWriter!
var writeInput:AVAssetWriterInput!
var bufferAdapter:AVAssetWriterInputPixelBufferAdaptor!
var videoSettings:[String : Any]!
var frameTime:CMTime!
//var fileURL:URL!
var completionBlock: CXEMovieMakerCompletion?
var movieMakerUIImageExtractor:CXEMovieMakerUIImageExtractor?
public class func videoSettings(codec:String, width:Int, height:Int) -> [String: Any]{
if(Int(width) % 16 != 0){
print("warning: video settings width must be divisible by 16")
}
let videoSettings:[String: Any] = [AVVideoCodecKey: AVVideoCodecJPEG, //AVVideoCodecH264,
AVVideoWidthKey: width,
AVVideoHeightKey: height]
return videoSettings
}
public init(videoSettings: [String: Any]) {
super.init()
if(FileManager.default.fileExists(atPath: ImagesToVideoUtils.tempPath)){
guard (try? FileManager.default.removeItem(atPath: ImagesToVideoUtils.tempPath)) != nil else {
print("remove path failed")
return
}
}
self.assetWriter = try! AVAssetWriter(url: ImagesToVideoUtils.fileURL, fileType: AVFileTypeQuickTimeMovie)
self.videoSettings = videoSettings
self.writeInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: videoSettings)
assert(self.assetWriter.canAdd(self.writeInput), "add failed")
self.assetWriter.add(self.writeInput)
let bufferAttributes:[String: Any] = [kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32ARGB)]
self.bufferAdapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: self.writeInput, sourcePixelBufferAttributes: bufferAttributes)
self.frameTime = CMTimeMake(1, 5)
}
func createMovieFrom(urls: [URL], withCompletion: @escaping CXEMovieMakerCompletion){
self.createMovieFromSource(images: urls as [AnyObject], extractor:{(inputObject:AnyObject) ->UIImage? in
return UIImage(data: try! Data(contentsOf: inputObject as! URL))}, withCompletion: withCompletion)
}
func createMovieFrom(images: [UIImage], withCompletion: @escaping CXEMovieMakerCompletion){
self.createMovieFromSource(images: images, extractor: {(inputObject:AnyObject) -> UIImage? in
return inputObject as? UIImage}, withCompletion: withCompletion)
}
func createMovieFromSource(images: [AnyObject], extractor: @escaping CXEMovieMakerUIImageExtractor, withCompletion: @escaping CXEMovieMakerCompletion){
self.completionBlock = withCompletion
self.assetWriter.startWriting()
self.assetWriter.startSession(atSourceTime: kCMTimeZero)
let mediaInputQueue = DispatchQueue(label: "mediaInputQueue")
var i = 0
let frameNumber = images.count
self.writeInput.requestMediaDataWhenReady(on: mediaInputQueue){
while(true){
if(i >= frameNumber){
break
}
if (self.writeInput.isReadyForMoreMediaData){
var sampleBuffer:CVPixelBuffer?
autoreleasepool{
let img = extractor(images[i])
if img == nil{
i += 1
print("Warning: counld not extract one of the frames")
//continue
}
sampleBuffer = self.newPixelBufferFrom(cgImage: img!.cgImage!)
}
if (sampleBuffer != nil){
if(i == 0){
self.bufferAdapter.append(sampleBuffer!, withPresentationTime: kCMTimeZero)
}else{
let value = i - 1
let lastTime = CMTimeMake(Int64(value), self.frameTime.timescale)
let presentTime = CMTimeAdd(lastTime, self.frameTime)
self.bufferAdapter.append(sampleBuffer!, withPresentationTime: presentTime)
}
i = i + 1
}
}
}
self.writeInput.markAsFinished()
self.assetWriter.finishWriting {
DispatchQueue.main.sync {
self.completionBlock!(ImagesToVideoUtils.fileURL)
}
}
}
}
func newPixelBufferFrom(cgImage:CGImage) -> CVPixelBuffer?{
let options:[String: Any] = [kCVPixelBufferCGImageCompatibilityKey as String: true, kCVPixelBufferCGBitmapContextCompatibilityKey as String: true]
var pxbuffer:CVPixelBuffer?
let frameWidth = self.videoSettings[AVVideoWidthKey] as! Int
let frameHeight = self.videoSettings[AVVideoHeightKey] as! Int
let status = CVPixelBufferCreate(kCFAllocatorDefault, frameWidth, frameHeight, kCVPixelFormatType_32ARGB, options as CFDictionary?, &pxbuffer)
assert(status == kCVReturnSuccess && pxbuffer != nil, "newPixelBuffer failed")
CVPixelBufferLockBaseAddress(pxbuffer!, CVPixelBufferLockFlags(rawValue: 0))
let pxdata = CVPixelBufferGetBaseAddress(pxbuffer!)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(data: pxdata, width: frameWidth, height: frameHeight, bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pxbuffer!), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)
assert(context != nil, "context is nil")
context!.concatenate(CGAffineTransform.identity)
context!.draw(cgImage, in: CGRect(x: 0, y: 0, width: cgImage.width, height: cgImage.height))
CVPixelBufferUnlockBaseAddress(pxbuffer!, CVPixelBufferLockFlags(rawValue: 0))
return pxbuffer
}
}
对于那些在2020年仍在进行编程之旅的人，如果电影不是16像素宽度而出现扭曲，请进行以下更改：
更改
CGContextRef context = CGBitmapContextCreate(pxdata,
width, height,
8, 4 * width,
rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
到
CGContextRef context = CGBitmapContextCreate(pxdata,
width, height,
8, CVPixelBufferGetBytesPerRow(pxbuffer),
rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
感谢 @bluedays AVAssetWriter 输出（将 UIImages 写入视频）失真。
这在纯Objective-C中实现起来有点困难...如果你是为越狱设备开发的，一个好主意是在应用程序内部使用命令行工具ffmpeg。使用类似以下命令的命令很容易从图像创建电影：
ffmpeg -r 10 -b 1800 -i %03d.jpg test1800.mp4
AVFoundation和FFmpeg都已经有帖子了。如果你正在寻找一些关于AVFoundation的信息，那么你会喜欢看到这个帖子吗？（或者这是 Meta 上的共识吗？） - zoul