我有一个项目，用户可以在其中拍摄视频，以后再向其中添加滤镜或更改基本设置（例如亮度和对比度）。为此，我使用BBMetalImage，它基本上以MTKView返回视频（在项目中命名为BBMetalView）。
一切都很好-我可以播放视频，添加滤镜和所需的效果，但是没有音频。关于此，我asked the author推荐使用AVPlayer（或AVAudioPlayer）。所以我做了。但是，视频和音频不同步。可能首先是因为比特率不同，并且库的作者还提到帧速率可能因过滤过程而有所不同（这消耗的时间是可变的）：
渲染视图的FPS与实际速率不完全相同。由于视频源输出帧是由过滤器和过滤器的处理时间是可变的。
[首先，我将视频裁剪为所需的宽高比（4：5）。我使用AVVideoProfileLevelH264HighAutoLevel作为AVVideoProfileLevelKey在本地保存了该文件（480x600）。使用NextLevelSessionExporter的音频配置具有以下设置：AVEncoderBitRateKey: 128000，AVNumberOfChannelsKey: 2，AVSampleRateKey: 44100。
然后，BBMetalImage库将获取此保存的音频文件，并提供MTKView（BBMetalView）来显示视频，使我可以实时添加滤镜和效果。设置看起来像这样：
self.metalView = BBMetalView(frame: CGRect(x: 0, y: self.view.center.y - ((UIScreen.main.bounds.width * 1.25) / 2), width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.width * 1.25))
self.view.addSubview(self.metalView)
self.videoSource = BBMetalVideoSource(url: outputURL)
self.videoSource.playWithVideoRate = true
self.videoSource.audioConsumer = self.metalAudio
self.videoSource.add(consumer: self.metalView)
self.videoSource.add(consumer: self.videoWriter)
self.audioItem = AVPlayerItem(url: outputURL)
self.audioPlayer = AVPlayer(playerItem: self.audioItem)
self.playerLayer = AVPlayerLayer(player: self.audioPlayer)
self.videoPreview.layer.addSublayer(self.playerLayer!)
self.playerLayer?.frame = CGRect(x: 0, y: 0, width: 0, height: 0)
self.playerLayer?.backgroundColor = UIColor.black.cgColor
self.startVideo()
[startVideo()像这样：
audioPlayer.seek(to: .zero)
audioPlayer.play()
videoSource.start(progress: { (frameTime) in
print(frameTime)
}) { [weak self] (finish) in
guard let self = self else { return }
self.startVideo()
}
由于外部库/库，这可能都非常模糊。但是，我的问题很简单：有什么办法可以使MTKView与AVPlayer同步？这将对我有很大帮助，并且我相信Silence-GitHub还将在库中实现此功能，以帮助许多其他用户。欢迎提出任何有关如何解决此问题的想法！
由于您的情况，您似乎需要尝试两种方法中的一种：
[1）尝试应用某种对您的视频具有理想效果的叠加层。我可以尝试这样的操作，但是我个人没有这样做。
2）之前需要花费更多时间-从某种意义上说，该程序将需要一些时间（取决于您的过滤条件，时间会有所不同），以重新制作具有所需效果的新视频。您可以尝试一下，看看它是否适合您。
我使用某个地方的SO源代码制作了自己的VideoCreator。
//Recreates a new video with applied filter
public static func createFilteredVideo(asset: AVAsset, completionHandler: @escaping (_ asset: AVAsset) -> Void) {
let url = (asset as? AVURLAsset)!.url
let snapshot = url.videoSnapshot()
guard let image = snapshot else { return }
let fps = Int32(asset.tracks(withMediaType: .video)[0].nominalFrameRate)
let writer = VideoCreator(fps: Int32(fps), width: image.size.width, height: image.size.height, audioSettings: nil)
let timeScale = asset.duration.timescale
let timeValue = asset.duration.value
let frameTime = 1/Double(fps) * Double(timeScale)
let numberOfImages = Int(Double(timeValue)/Double(frameTime))
let queue = DispatchQueue(label: "com.queue.queue", qos: .utility)
let composition = AVVideoComposition(asset: asset) { (request) in
let source = request.sourceImage.clampedToExtent()
//This is where you create your filter and get your filtered result.
//Here is an example
let filter = CIFilter(name: "CIBlendWithMask")
filter!.setValue(maskImage, forKey: "inputMaskImage")
filter!.setValue(regCIImage, forKey: "inputImage")
let filteredImage = filter!.outputImage.clamped(to: source.extent)
request.finish(with: filteredImage, context: nil)
}
var i = 0
getAudioFromURL(url: url) { (buffer) in
writer.addAudio(audio: buffer, time: .zero)
i == 0 ? writer.startCreatingVideo(initialBuffer: buffer, completion: {}) : nil
i += 1
}
let group = DispatchGroup()
for i in 0..<numberOfImages {
group.enter()
autoreleasepool {
let time = CMTime(seconds: Double(Double(i) * frameTime / Double(timeScale)), preferredTimescale: timeScale)
let image = url.videoSnapshot(time: time, composition: composition)
queue.async {
writer.addImageAndAudio(image: image!, audio: nil, time: time.seconds)
group.leave()
}
}
}
group.notify(queue: queue) {
writer.finishWriting()
let url = writer.getURL()
//Now create exporter to add audio then do completion handler
completionHandler(AVAsset(url: url))
}
}
static func getAudioFromURL(url: URL, completionHandlerPerBuffer: @escaping ((_ buffer:CMSampleBuffer) -> Void)) {
let asset = AVURLAsset(url: url, options: [AVURLAssetPreferPreciseDurationAndTimingKey: NSNumber(value: true as Bool)])
guard let assetTrack = asset.tracks(withMediaType: AVMediaType.audio).first else {
fatalError("Couldn't load AVAssetTrack")
}
guard let reader = try? AVAssetReader(asset: asset)
else {
fatalError("Couldn't initialize the AVAssetReader")
}
reader.timeRange = CMTimeRange(start: .zero, duration: asset.duration)
let outputSettingsDict: [String : Any] = [
AVFormatIDKey: Int(kAudioFormatLinearPCM),
AVLinearPCMBitDepthKey: 16,
AVLinearPCMIsBigEndianKey: false,
AVLinearPCMIsFloatKey: false,
AVLinearPCMIsNonInterleaved: false
]
let readerOutput = AVAssetReaderTrackOutput(track: assetTrack,
outputSettings: outputSettingsDict)
readerOutput.alwaysCopiesSampleData = false
reader.add(readerOutput)
while reader.status == .reading {
guard let readSampleBuffer = readerOutput.copyNextSampleBuffer() else { break }
completionHandlerPerBuffer(readSampleBuffer)
}
}
extension URL {
func videoSnapshot(time:CMTime? = nil, composition:AVVideoComposition? = nil) -> UIImage? {
let asset = AVURLAsset(url: self)
let generator = AVAssetImageGenerator(asset: asset)
generator.appliesPreferredTrackTransform = true
generator.requestedTimeToleranceBefore = .zero
generator.requestedTimeToleranceAfter = .zero
generator.videoComposition = composition
let timestamp = time == nil ? CMTime(seconds: 1, preferredTimescale: 60) : time
do {
let imageRef = try generator.copyCGImage(at: timestamp!, actualTime: nil)
return UIImage(cgImage: imageRef)
}
catch let error as NSError
{
print("Image generation failed with error \(error)")
return nil
}
}
}
下面是VideoCreator
//
// VideoCreator.swift
// AKPickerView-Swift
//
// Created by Impression7vx on 7/16/19.
//
import UIKit
import AVFoundation
import UIKit
import Photos
@available(iOS 11.0, *)
public class VideoCreator: NSObject {
private var settings:RenderSettings!
private var imageAnimator:ImageAnimator!
public override init() {
self.settings = RenderSettings()
self.imageAnimator = ImageAnimator(renderSettings: self.settings)
}
public convenience init(fps: Int32, width: CGFloat, height: CGFloat, audioSettings: [String:Any]?) {
self.init()
self.settings = RenderSettings(fps: fps, width: width, height: height)
self.imageAnimator = ImageAnimator(renderSettings: self.settings, audioSettings: audioSettings)
}
public convenience init(width: CGFloat, height: CGFloat) {
self.init()
self.settings = RenderSettings(width: width, height: height)
self.imageAnimator = ImageAnimator(renderSettings: self.settings)
}
func startCreatingVideo(initialBuffer: CMSampleBuffer?, completion: @escaping (() -> Void)) {
self.imageAnimator.render(initialBuffer: initialBuffer) {
completion()
}
}
func finishWriting() {
self.imageAnimator.isDone = true
}
func addImageAndAudio(image:UIImage, audio:CMSampleBuffer?, time:CFAbsoluteTime) {
self.imageAnimator.addImageAndAudio(image: image, audio: audio, time: time)
}
func getURL() -> URL {
return settings!.outputURL
}
func addAudio(audio: CMSampleBuffer, time: CMTime) {
self.imageAnimator.videoWriter.addAudio(buffer: audio, time: time)
}
}
@available(iOS 11.0, *)
public struct RenderSettings {
var width: CGFloat = 1280
var height: CGFloat = 720
var fps: Int32 = 2 // 2 frames per second
var avCodecKey = AVVideoCodecType.h264
var videoFilename = "video"
var videoFilenameExt = "mov"
init() { }
init(width: CGFloat, height: CGFloat) {
self.width = width
self.height = height
}
init(fps: Int32) {
self.fps = fps
}
init(fps: Int32, width: CGFloat, height: CGFloat) {
self.fps = fps
self.width = width
self.height = height
}
var size: CGSize {
return CGSize(width: width, height: height)
}
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")
}
}
@available(iOS 11.0, *)
public 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 imagesAndAudio:SynchronizedArray<(UIImage, CMSampleBuffer?, CFAbsoluteTime)> = SynchronizedArray<(UIImage, CMSampleBuffer?, CFAbsoluteTime)>()
var isDone:Bool = false
let semaphore = DispatchSemaphore(value: 1)
var frameNum = 0
class func removeFileAtURL(fileURL: URL) {
do {
try FileManager.default.removeItem(atPath: fileURL.path)
}
catch _ as NSError {
// Assume file doesn't exist.
}
}
init(renderSettings: RenderSettings, audioSettings:[String:Any]? = nil) {
settings = renderSettings
videoWriter = VideoWriter(renderSettings: settings, audioSettings: audioSettings)
}
func addImageAndAudio(image: UIImage, audio: CMSampleBuffer?, time:CFAbsoluteTime) {
self.imagesAndAudio.append((image, audio, time))
// print("Adding to array -- \(self.imagesAndAudio.count)")
}
func render(initialBuffer: CMSampleBuffer?, completion: @escaping ()->Void) {
// The VideoWriter will fail if a file exists at the URL, so clear it out first.
ImageAnimator.removeFileAtURL(fileURL: settings.outputURL)
videoWriter.start(initialBuffer: initialBuffer)
videoWriter.render(appendPixelBuffers: appendPixelBuffers) {
//ImageAnimator.saveToLibrary(self.settings.outputURL)
completion()
}
}
// This is the callback function for VideoWriter.render()
func appendPixelBuffers(writer: VideoWriter) -> Bool {
//Don't stop while images are NOT empty
while !imagesAndAudio.isEmpty || !isDone {
if(!imagesAndAudio.isEmpty) {
let date = Date()
if writer.isReadyForVideoData == false {
// Inform writer we have more buffers to write.
// print("Writer is not ready for more data")
return false
}
autoreleasepool {
//This should help but truly doesn't suffice - still need a mutex/lock
if(!imagesAndAudio.isEmpty) {
semaphore.wait() // requesting resource
let imageAndAudio = imagesAndAudio.first()!
let image = imageAndAudio.0
// let audio = imageAndAudio.1
let time = imageAndAudio.2
self.imagesAndAudio.removeAtIndex(index: 0)
semaphore.signal() // releasing resource
let presentationTime = CMTime(seconds: time, preferredTimescale: 600)
// if(audio != nil) { videoWriter.addAudio(buffer: audio!) }
let success = videoWriter.addImage(image: image, withPresentationTime: presentationTime)
if success == false {
fatalError("addImage() failed")
}
else {
// print("Added image @ frame \(frameNum) with presTime: \(presentationTime)")
}
frameNum += 1
let final = Date()
let timeDiff = final.timeIntervalSince(date)
// print("Time: \(timeDiff)")
}
else {
// print("Images was empty")
}
}
}
}
print("Done writing")
// Inform writer all buffers have been written.
return true
}
}
@available(iOS 11.0, *)
public class VideoWriter {
let renderSettings: RenderSettings
var audioSettings: [String:Any]?
var videoWriter: AVAssetWriter!
var videoWriterInput: AVAssetWriterInput!
var pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor!
var audioWriterInput: AVAssetWriterInput!
static var ci:Int = 0
var initialTime:CMTime!
var isReadyForVideoData: Bool {
return (videoWriterInput == nil ? false : videoWriterInput!.isReadyForMoreMediaData )
}
var isReadyForAudioData: Bool {
return (audioWriterInput == nil ? false : audioWriterInput!.isReadyForMoreMediaData)
}
class func pixelBufferFromImage(image: UIImage, pixelBufferPool: CVPixelBufferPool, size: CGSize, alpha:CGImageAlphaInfo) -> CVPixelBuffer? {
var pixelBufferOut: CVPixelBuffer?
let status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pixelBufferOut)
if status != kCVReturnSuccess {
fatalError("CVPixelBufferPoolCreatePixelBuffer() failed")
}
let pixelBuffer = pixelBufferOut!
CVPixelBufferLockBaseAddress(pixelBuffer, [])
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: alpha.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
let cgImage = image.cgImage != nil ? image.cgImage! : image.ciImage!.convertCIImageToCGImage()
context!.draw(cgImage!, in: CGRect(x: x, y: y, width: newSize.width, height: newSize.height))
CVPixelBufferUnlockBaseAddress(pixelBuffer, [])
return pixelBuffer
}
@available(iOS 11.0, *)
init(renderSettings: RenderSettings, audioSettings:[String:Any]? = nil) {
self.renderSettings = renderSettings
self.audioSettings = audioSettings
}
func start(initialBuffer: CMSampleBuffer?) {
let avOutputSettings: [String: AnyObject] = [
AVVideoCodecKey: renderSettings.avCodecKey as AnyObject,
AVVideoWidthKey: NSNumber(value: Float(renderSettings.width)),
AVVideoHeightKey: NSNumber(value: Float(renderSettings.height))
]
let avAudioSettings = audioSettings
func createPixelBufferAdaptor() {
let sourcePixelBufferAttributesDictionary = [
kCVPixelBufferPixelFormatTypeKey as String: NSNumber(value: kCVPixelFormatType_32ARGB),
kCVPixelBufferWidthKey as String: NSNumber(value: Float(renderSettings.width)),
kCVPixelBufferHeightKey as String: NSNumber(value: Float(renderSettings.height))
]
pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput,
sourcePixelBufferAttributes: sourcePixelBufferAttributesDictionary)
}
func createAssetWriter(outputURL: URL) -> AVAssetWriter {
guard let assetWriter = try? AVAssetWriter(outputURL: outputURL, fileType: AVFileType.mov) 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(audioSettings != nil) {
audioWriterInput = AVAssetWriterInput(mediaType: .audio, outputSettings: nil)
audioWriterInput.expectsMediaDataInRealTime = true
// }
if videoWriter.canAdd(videoWriterInput) {
videoWriter.add(videoWriterInput)
}
else {
fatalError("canAddInput() returned false")
}
// if(audioSettings != nil) {
if videoWriter.canAdd(audioWriterInput) {
videoWriter.add(audioWriterInput)
}
else {
fatalError("canAddInput() returned false")
}
// }
// The pixel buffer adaptor must be created before we start writing.
createPixelBufferAdaptor()
if videoWriter.startWriting() == false {
fatalError("startWriting() failed")
}
self.initialTime = initialBuffer != nil ? CMSampleBufferGetPresentationTimeStamp(initialBuffer!) : CMTime.zero
videoWriter.startSession(atSourceTime: self.initialTime)
precondition(pixelBufferAdaptor.pixelBufferPool != nil, "nil pixelBufferPool")
}
func render(appendPixelBuffers: @escaping (VideoWriter)->Bool, completion: @escaping ()->Void) {
precondition(videoWriter != nil, "Call start() to initialze the writer")
let queue = DispatchQueue(__label: "mediaInputQueue", attr: nil)
videoWriterInput.requestMediaDataWhenReady(on: queue) {
let isFinished = appendPixelBuffers(self)
if isFinished {
self.videoWriterInput.markAsFinished()
self.videoWriter.finishWriting() {
DispatchQueue.main.async {
print("Done Creating Video")
completion()
}
}
}
else {
// Fall through. The closure will be called again when the writer is ready.
}
}
}
func addAudio(buffer: CMSampleBuffer, time: CMTime) {
if(isReadyForAudioData) {
print("Writing audio \(VideoWriter.ci) of a time of \(CMSampleBufferGetPresentationTimeStamp(buffer))")
let duration = CMSampleBufferGetDuration(buffer)
let offsetBuffer = CMSampleBuffer.createSampleBuffer(fromSampleBuffer: buffer, withTimeOffset: time, duration: duration)
if(offsetBuffer != nil) {
print("Added audio")
self.audioWriterInput.append(offsetBuffer!)
}
else {
print("Not adding audio")
}
}
VideoWriter.ci += 1
}
func addImage(image: UIImage, withPresentationTime presentationTime: CMTime) -> Bool {
precondition(pixelBufferAdaptor != nil, "Call start() to initialze the writer")
//1
let pixelBuffer = VideoWriter.pixelBufferFromImage(image: image, pixelBufferPool: pixelBufferAdaptor.pixelBufferPool!, size: renderSettings.size, alpha: CGImageAlphaInfo.premultipliedFirst)!
return pixelBufferAdaptor.append(pixelBuffer, withPresentationTime: presentationTime + self.initialTime)
}
}
我正在进一步研究-尽管可以更新我的答案，但我希望在新的领域中打开切线以分离这些想法。 Apple声明我们可以使用AVVideoComposition来“要使用创建的视频合成进行回放，请从与合成来源相同的资产中创建一个AVPlayerItem对象，然后将该合成分配给播放器项目的videoComposition属性。要导出合成到新的电影文件，请从相同的源资产创建一个AVAssetExportSession对象，然后将构图分配给导出会话的videoComposition属性。“]
https://developer.apple.com/documentation/avfoundation/avasynchronousciimagefilteringrequest
因此，您可以尝试使用AVPlayer作为原始URL。然后尝试应用您的过滤器。
let filter = CIFilter(name: "CIGaussianBlur")!
let composition = AVVideoComposition(asset: asset, applyingCIFiltersWithHandler: { request in
// Clamp to avoid blurring transparent pixels at the image edges
let source = request.sourceImage.imageByClampingToExtent()
filter.setValue(source, forKey: kCIInputImageKey)
// Vary filter parameters based on video timing
let seconds = CMTimeGetSeconds(request.compositionTime)
filter.setValue(seconds * 10.0, forKey: kCIInputRadiusKey)
// Crop the blurred output to the bounds of the original image
let output = filter.outputImage!.imageByCroppingToRect(request.sourceImage.extent)
// Provide the filter output to the composition
request.finishWithImage(output, context: nil)
})
let asset = AVAsset(url: originalURL)
let item = AVPlayerItem(asset: asset)
item.videoComposition = composition
let player = AVPlayer(playerItem: item)
我确定您知道从这里做什么。这可能使您可以“实时”进行过滤。我可以看到的潜在问题是，这和您原来遇到的问题一样，而运行每一帧仍需要花费一定的时间，并导致音频和视频之间的延迟。但是，这可能不会发生。如果您确实可以使用，则用户选择过滤器后，即可使用AVAssetExportSession导出特定的videoComposition。
更多here，如果您需要帮助！