我正在使用 Apple 的 AVCamFilter 演示应用程序。不幸的是，它不包括电影录制功能，所以我尝试在照片输出的正下方、类的顶部创建一个电影输出：
let movieOutput = AVCaptureMovieFileOutput()
然后我在
configureSession()if session.canAddOutput(movieOutput) {
session.addOutput(movieOutput)
} else {
print("Could not add movie output to the session")
setupResult = .configurationFailed
session.commitConfiguration()
return
}
在我的 iPhone (13 Pro) 上，这有效，我可以成功录制视频。但在我的 iPad Air 上，相机预览却变黑了。没有出现错误，并且
setupResult我没有对项目进行其他修改，因此您可以通过下载演示应用程序并添加这些行来亲自尝试。
更新：我发现了一些有关
AVCaptureMovieFileOutputAVCaptureVideoDataOutput我从来不明白为什么它能在我的 iPhone 上运行，但作为一种解决方法，我实现了 AVAssetWriter。这应该允许 AVCamFilter 在任何设备上录制视频（和音频！）。
首先，在顶部添加这些变量：
let audioSession = AVCaptureSession()
private let audioDataOutputQueue = DispatchQueue(label: "AudioDataQueue", qos: .userInitiated, attributes: [], autoreleaseFrequency: .workItem)
private let audioDataOutput = AVCaptureAudioDataOutput()
private var _assetWriter: AVAssetWriter?
private var _assetWriterVideoInput: AVAssetWriterInput?
private var _assetWriterAudioInput: AVAssetWriterInput?
private var _adpater: AVAssetWriterInputPixelBufferAdaptor?
private var _filename = ""
private var _time: Double = 0
private var _captureState = _CaptureState.idle
private enum _CaptureState {
case idle, start, capturing, end
}
我将音频放在单独的会话中，因为我想包含触觉（请参阅下面的注释），但如果您愿意，您可以将它们放在同一个会话中。
在
configureSession()session.commitConfiguration()audioSession.beginConfiguration()
// Add an audio input
let audioDevice = AVCaptureDevice.default(for: .audio)
let audioInput = try! AVCaptureDeviceInput(device: audioDevice!)
if audioSession.canAddInput(audioInput) {
audioSession.addInput(audioInput)
}
// Add an audio data output
if audioSession.canAddOutput(audioDataOutput) {
audioSession.addOutput(audioDataOutput)
audioDataOutput.setSampleBufferDelegate(self, queue: audioDataOutputQueue)
} else {
print("Could not add audio data output to the session")
}
audioSession.commitConfiguration()
然后将
captureOutput(_ didOutput from:)if connection.output == videoDataOutput {
processVideo(sampleBuffer: sampleBuffer)
}
let timestamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer).seconds
switch _captureState {
case .start:
// Set up recorder
_filename = UUID().uuidString
let videoPath = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("\(_filename).mov")
let writer = try! AVAssetWriter(outputURL: videoPath, fileType: .mov)
let settings = videoDataOutput.recommendedVideoSettingsForAssetWriter(writingTo: .mov)
let input = AVAssetWriterInput(mediaType: .video, outputSettings: settings) // [AVVideoCodecKey: AVVideoCodecType.h264, AVVideoWidthKey: 1920, AVVideoHeightKey: 1080])
input.mediaTimeScale = CMTimeScale(bitPattern: 600)
input.expectsMediaDataInRealTime = true
input.transform = CGAffineTransform(rotationAngle: .pi/2)
let adapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: input, sourcePixelBufferAttributes: nil)
if writer.canAdd(input) {
writer.add(input)
}
let audioSettings = audioDataOutput.recommendedAudioSettingsForAssetWriter(writingTo: .mov)
let audioInput = AVAssetWriterInput(mediaType: .audio, outputSettings: audioSettings)
audioInput.expectsMediaDataInRealTime = true
if writer.canAdd(audioInput) {
writer.add(audioInput)
}
writer.startWriting()
writer.startSession(atSourceTime: .zero)
_assetWriter = writer
_assetWriterVideoInput = input
_assetWriterAudioInput = audioInput
_adpater = adapter
_captureState = .capturing
_time = timestamp
case .capturing:
if connection.output == videoDataOutput {
// Process video frames and write to videoInput
if _assetWriterVideoInput?.isReadyForMoreMediaData == true {
let time = CMTime(seconds: timestamp - _time, preferredTimescale: CMTimeScale(600))
_adpater?.append(previewView.pixelBuffer!, withPresentationTime: time)
}
} else if connection.output == audioDataOutput {
// Process audio samples and write to audioInput
if _assetWriterAudioInput!.isReadyForMoreMediaData {
let time = CMTime(seconds: timestamp - _time, preferredTimescale: CMTimeScale(600))
if let modifiedBuffer = setPresentationTimestamp(sampleBuffer: sampleBuffer, presentationTimestamp: time) {
_assetWriterAudioInput!.append(modifiedBuffer)
}
}
}
break
case .end:
guard _assetWriterVideoInput?.isReadyForMoreMediaData == true, _assetWriter!.status != .failed else { break }
let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("\(_filename).mov")
_assetWriterVideoInput?.markAsFinished()
_assetWriterAudioInput?.markAsFinished()
_assetWriter?.finishWriting { [weak self] in
self?._captureState = .idle
self?._assetWriter = nil
self?._assetWriterVideoInput = nil
self?._assetWriterAudioInput = nil
UISaveVideoAtPathToSavedPhotosAlbum(url.path, nil, nil, nil)
}
default:
break
}
（你可以用URL做任何你想做的事，这里以保存到照片库为例）
最后，您需要它来同步音频和视频：
func setPresentationTimestamp(sampleBuffer: CMSampleBuffer, presentationTimestamp: CMTime) -> CMSampleBuffer? {
var sampleBufferCopy: CMSampleBuffer? = nil
var timingInfoArray = [CMSampleTimingInfo(duration: CMTimeMake(value: 1, timescale: 30), presentationTimeStamp: presentationTimestamp, decodeTimeStamp: CMTime.invalid)]
var status = CMSampleBufferCreateCopyWithNewTiming(allocator: kCFAllocatorDefault, sampleBuffer: sampleBuffer, sampleTimingEntryCount: 1, sampleTimingArray: &timingInfoArray, sampleBufferOut: &sampleBufferCopy)
if status == noErr {
return sampleBufferCopy
} else {
// Handle the error
return nil
}
}
要实际触发视频录制，请将
_captureState.start.end备注：
-您可能会在视频的开头和结尾看到黑帧。我尝试了多种方法来解决这个问题，但没有任何效果，所以我将
writer.startSession(atSourceTime: .zero)writer.startSession(atSourceTime: CMTime(seconds: 0.25, preferredTimescale: CMTimeScale(600)))_assetWriterVideoInput?.markAsFinished()let endTime = timestamp - _time
_assetWriter?.endSession(atSourceTime: CMTime(seconds: endTime, preferredTimescale: CMTimeScale(600)))
-运行麦克风会禁用触觉。这就是我使用单独的音频会话的原因：这样我就可以告诉会话在视频录制开始时开始运行，并在结束时停止运行。只要不录音，您就应该能够使用触觉。请注意，您当然必须获得音频权限才能进行录音。
-一些 AVAssetWriter 代码请参见此处：https://gist.github.com/yusuke024/b5cd3909d9d7f9e919291491f6b381f0
-我绝不是专家！所以任何人都可以随意指出这里是否有不必要/错误的地方。