AVAssetWriterInput追加失败，错误代码为-11800 AVErrorUnknown -12780

Question

我正在尝试使用AVCaptureSession在内存中捕获相机视频，以便稍后我可以将视频数据写入电影文件。 虽然我已经能够成功启动捕获会话，但我无法使用AVAssetWriter将已捕获的CMSampleBuffers成功写入压缩的电影文件。

使用AVAssetWriterInput的append方法追加样本缓冲区失败，当我检查AVAssetWriter的error属性时，我得到以下内容：

错误域= AVFoundationErrorDomain代码= -11800“操作无法完成”UserInfo = {NSUnderlyingError = 0x17005d070 {错误域= NSOSStatusErrorDomain代码= -12780“（null）”}，NSLocalizedFailureReason =发生未知错误（-12780），NSLocalizedDescription =操作无法完成}

据我所知 - -11800表示AVErrorUnknown，但是我无法找到有关-12780错误代码的信息，据我所知，该错误代码没有记录。 下面我已经粘贴了我设置的示例项目中的主要文件来演示问题。

任何指导将不胜感激。 谢谢！

ViewController.swift

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {

    private let recordingClipQueue = DispatchQueue(label: "com.example.recordingClipQueue")
    private let videoDataOutputQueue = DispatchQueue(label: "com.example.videoDataOutputQueue")
    private let session = AVCaptureSession()
    private var backfillSampleBufferList = [CMSampleBuffer]()

    override func viewDidLoad() {
        super.viewDidLoad()

        session.sessionPreset = AVCaptureSessionPreset640x480

        let videoDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo);
        let videoDeviceInput: AVCaptureDeviceInput;

        do {
            videoDeviceInput = try AVCaptureDeviceInput(device: videoDevice)
        } catch {
            print("Error creating device input from video device: \(error).")
            return
        }

        guard session.canAddInput(videoDeviceInput) else {
            print("Could not add video device input to capture session.")
            return
        }

        session.addInput(videoDeviceInput)

        let videoDataOutput = AVCaptureVideoDataOutput()
        videoDataOutput.videoSettings = [ kCVPixelBufferPixelFormatTypeKey as NSString : Int(kCMPixelFormat_32BGRA) ]
        videoDataOutput.alwaysDiscardsLateVideoFrames = true
        videoDataOutput.setSampleBufferDelegate(self, queue: videoDataOutputQueue)

        guard session.canAddOutput(videoDataOutput) else {
            print("Could not add video data output to capture session.")
            return
        }

        session.addOutput(videoDataOutput)
        videoDataOutput.connection(withMediaType: AVMediaTypeVideo).isEnabled = true

        session.startRunning()
    }

    private func backfillSizeInSeconds() -> Double {
        if backfillSampleBufferList.count < 1 {
            return 0.0
        }

        let earliestSampleBuffer = backfillSampleBufferList.first!
        let latestSampleBuffer = backfillSampleBufferList.last!

        let earliestSampleBufferPTS = CMSampleBufferGetOutputPresentationTimeStamp(earliestSampleBuffer).value
        let latestSampleBufferPTS = CMSampleBufferGetOutputPresentationTimeStamp(latestSampleBuffer).value
        let timescale = CMSampleBufferGetOutputPresentationTimeStamp(latestSampleBuffer).timescale

        return Double(latestSampleBufferPTS - earliestSampleBufferPTS) / Double(timescale)
    }

    private func createClipFromBackfill() {
        guard backfillSampleBufferList.count > 0 else {
            print("createClipFromBackfill() called before any samples were recorded.")
            return
        }

        let clipURL = URL(fileURLWithPath:
            NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] +
            "/recorded_clip.mp4")

        if FileManager.default.fileExists(atPath: clipURL.path) {
            do {
                try FileManager.default.removeItem(atPath: clipURL.path)
            } catch {
                print("Could not delete existing clip file: \(error).")
            }
        }

        var _videoFileWriter: AVAssetWriter?
        do {
            _videoFileWriter = try AVAssetWriter(url: clipURL, fileType: AVFileTypeQuickTimeMovie)
        } catch {
            print("Could not create video file writer: \(error).")
            return
        }

        guard let videoFileWriter = _videoFileWriter else {
            print("Video writer was nil.")
            return
        }

        let settingsAssistant = AVOutputSettingsAssistant(preset: AVOutputSettingsPreset640x480)!

        guard videoFileWriter.canApply(outputSettings: settingsAssistant.videoSettings, forMediaType: AVMediaTypeVideo) else {
            print("Video file writer could not apply video output settings.")
            return
        }

        let earliestRecordedSampleBuffer = backfillSampleBufferList.first!

        let _formatDescription = CMSampleBufferGetFormatDescription(earliestRecordedSampleBuffer)
        guard let formatDescription = _formatDescription else {
            print("Earliest recording pixel buffer format description was nil.")
            return
        }

        let videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo,
                                                  outputSettings: settingsAssistant.videoSettings,
                                                  sourceFormatHint: formatDescription)

        guard videoFileWriter.canAdd(videoWriterInput) else {
            print("Could not add video writer input to video file writer.")
            return
        }

        videoFileWriter.add(videoWriterInput)

        guard videoFileWriter.startWriting() else {
            print("Video file writer not ready to write file.")
            return
        }

        videoFileWriter.startSession(atSourceTime: CMSampleBufferGetOutputPresentationTimeStamp(earliestRecordedSampleBuffer))

        videoWriterInput.requestMediaDataWhenReady(on: recordingClipQueue) {
            while videoWriterInput.isReadyForMoreMediaData {
                if self.backfillSampleBufferList.count > 0 {
                    let sampleBufferToAppend = self.backfillSampleBufferList.first!.deepCopy()
                    let appendSampleBufferSucceeded = videoWriterInput.append(sampleBufferToAppend)
                    if !appendSampleBufferSucceeded {
                        print("Failed to append sample buffer to asset writer input: \(videoFileWriter.error!)")
                        print("Video file writer status: \(videoFileWriter.status.rawValue)")
                    }

                    self.backfillSampleBufferList.remove(at: 0)
                } else {
                    videoWriterInput.markAsFinished()
                    videoFileWriter.finishWriting {
                        print("Saved clip to \(clipURL)")
                    }

                    break
                }
            }
        }
    }

    // MARK: AVCaptureVideoDataOutputSampleBufferDelegate

    func captureOutput(_ captureOutput: AVCaptureOutput!,
                       didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
                       from connection: AVCaptureConnection!) {
        guard let buffer = sampleBuffer else {
            print("Captured sample buffer was nil.")
            return
        }

        let sampleBufferCopy = buffer.deepCopy()

        backfillSampleBufferList.append(sampleBufferCopy)

        if backfillSizeInSeconds() > 3.0 {
            session.stopRunning()
            createClipFromBackfill()
        }
    }

    func captureOutput(_ captureOutput: AVCaptureOutput!,
                       didDrop sampleBuffer: CMSampleBuffer!,
                       from connection: AVCaptureConnection!) {
        print("Sample buffer dropped.")
    }

}

CVPixelBuffer + Copy.swift：

import CoreVideo

extension CVPixelBuffer {
    func deepCopy() -> CVPixelBuffer {
        precondition(CFGetTypeID(self) == CVPixelBufferGetTypeID(), "deepCopy() cannot copy a non-CVPixelBuffer")

        var _copy : CVPixelBuffer?
        CVPixelBufferCreate(
            nil,
            CVPixelBufferGetWidth(self),
            CVPixelBufferGetHeight(self),
            CVPixelBufferGetPixelFormatType(self),
            CVBufferGetAttachments(self, CVAttachmentMode.shouldPropagate),
            &_copy)

        guard let copy = _copy else {
            print("Pixel buffer copy was nil.")
            fatalError()
        }

        CVBufferPropagateAttachments(self, copy)
        CVPixelBufferLockBaseAddress(self, CVPixelBufferLockFlags.readOnly)
        CVPixelBufferLockBaseAddress(copy, CVPixelBufferLockFlags(rawValue: 0))

        let sourceBaseAddress = CVPixelBufferGetBaseAddress(self)
        let copyBaseAddress = CVPixelBufferGetBaseAddress(copy)
        memcpy(copyBaseAddress, sourceBaseAddress, CVPixelBufferGetHeight(self) * CVPixelBufferGetBytesPerRow(self))

        CVPixelBufferUnlockBaseAddress(copy, CVPixelBufferLockFlags(rawValue: 0))
        CVPixelBufferUnlockBaseAddress(self, CVPixelBufferLockFlags.readOnly)

        return copy
    }
}

CMSampleBuffer + Copy.swift：

import CoreMedia

extension CMSampleBuffer {
    func deepCopy() -> CMSampleBuffer {
        let _pixelBuffer = CMSampleBufferGetImageBuffer(self)
        guard let pixelBuffer = _pixelBuffer else {
            print("Pixel buffer to copy was nil.")
            fatalError()
        }
        let pixelBufferCopy = pixelBuffer.deepCopy()

        let _formatDescription = CMSampleBufferGetFormatDescription(self)
        guard let formatDescription = _formatDescription else {
            print("Format description to copy was nil.")
            fatalError()
        }

        var timingInfo = kCMTimingInfoInvalid
        let getTimingInfoResult = CMSampleBufferGetSampleTimingInfo(self, 0, &timingInfo)
        guard getTimingInfoResult == noErr else {
            print("Could not get timing info to copy: \(getTimingInfoResult).")
            fatalError()
        }

        timingInfo.presentationTimeStamp = CMSampleBufferGetOutputPresentationTimeStamp(self)

        var _copy : CMSampleBuffer?
        let createCopyResult = CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault,
                                                                  pixelBufferCopy,
                                                                  true,
                                                                  nil,
                                                                  nil,
                                                                  formatDescription,
                                                                  &timingInfo,
                                                                  &_copy);

        guard createCopyResult == noErr else {
            print("Error creating copy of sample buffer: \(createCopyResult).")
            fatalError()
        }

        guard let copy = _copy else {
            print("Copied sample buffer was nil.")
            fatalError()
        }

        return copy
    }
}

Answer 1

在尝试合成视频时我也碰到了这个。 我终于发现-[AVAssetWriterInput appendSampleBuffer:]仅适用于设备（​​无论如何，从iOS 11.2.6开始），如果基础像素缓冲区由IOSurface支持。

如果修改CVPixelBuffer.deepCopy()方法以在属性字典中包含(id)kCVPixelBufferIOSurfacePropertiesKey: @{}键值对，则传递给CVPixelBufferCreate ，它可能会起作用。

Answer 2

经过更多的研究和实验，它似乎使用AVAssetWriterInputPixelBufferAdaptor将我存储的CMSampleBuffers的CVPixelBuffers附加到AVAssetWriterInput工作而不会产生错误。

下面是ViewController.swift实现的修改版本，它使用AVAssetWriterInputPixelBufferAdaptor附加像素缓冲区。

ViewController.swift

import UIKit
import AVFoundation
import Photos

class ViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {

    private let recordingClipQueue = DispatchQueue(label: "com.example.recordingClipQueue")
    private let videoDataOutputQueue = DispatchQueue(label: "com.example.videoDataOutputQueue")
    private let session = AVCaptureSession()
    private var backfillSampleBufferList = [CMSampleBuffer]()

    override func viewDidLoad() {
        super.viewDidLoad()

        session.sessionPreset = AVCaptureSessionPreset640x480

        let videoDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo);
        let videoDeviceInput: AVCaptureDeviceInput;

        do {
            videoDeviceInput = try AVCaptureDeviceInput(device: videoDevice)
        } catch {
            print("Error creating device input from video device: \(error).")
            return
        }

        guard session.canAddInput(videoDeviceInput) else {
            print("Could not add video device input to capture session.")
            return
        }

        session.addInput(videoDeviceInput)

        let videoDataOutput = AVCaptureVideoDataOutput()
        videoDataOutput.videoSettings = [ kCVPixelBufferPixelFormatTypeKey as NSString : Int(kCMPixelFormat_32BGRA) ]
        videoDataOutput.alwaysDiscardsLateVideoFrames = true
        videoDataOutput.setSampleBufferDelegate(self, queue: videoDataOutputQueue)

        guard session.canAddOutput(videoDataOutput) else {
            print("Could not add video data output to capture session.")
            return
        }

        session.addOutput(videoDataOutput)
        videoDataOutput.connection(withMediaType: AVMediaTypeVideo).isEnabled = true

        session.startRunning()
    }

    private func backfillSizeInSeconds() -> Double {
        if backfillSampleBufferList.count < 1 {
            return 0.0
        }

        let earliestSampleBuffer = backfillSampleBufferList.first!
        let latestSampleBuffer = backfillSampleBufferList.last!

        let earliestSampleBufferPTS = CMSampleBufferGetOutputPresentationTimeStamp(earliestSampleBuffer).value
        let latestSampleBufferPTS = CMSampleBufferGetOutputPresentationTimeStamp(latestSampleBuffer).value
        let timescale = CMSampleBufferGetOutputPresentationTimeStamp(latestSampleBuffer).timescale

        return Double(latestSampleBufferPTS - earliestSampleBufferPTS) / Double(timescale)
    }

    private func createClipFromBackfill() {
        guard backfillSampleBufferList.count > 0 else {
            print("createClipFromBackfill() called before any samples were recorded.")
            return
        }

        let clipURL = URL(fileURLWithPath:
            NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] +
            "/recorded_clip.mp4")

        if FileManager.default.fileExists(atPath: clipURL.path) {
            do {
                try FileManager.default.removeItem(atPath: clipURL.path)
            } catch {
                print("Could not delete existing clip file: \(error).")
            }
        }

        var _videoFileWriter: AVAssetWriter?
        do {
            _videoFileWriter = try AVAssetWriter(url: clipURL, fileType: AVFileTypeMPEG4)
        } catch {
            print("Could not create video file writer: \(error).")
            return
        }

        guard let videoFileWriter = _videoFileWriter else {
            print("Video writer was nil.")
            return
        }

        let settingsAssistant = AVOutputSettingsAssistant(preset: AVOutputSettingsPreset640x480)!

        guard videoFileWriter.canApply(outputSettings: settingsAssistant.videoSettings, forMediaType: AVMediaTypeVideo) else {
            print("Video file writer could not apply video output settings.")
            return
        }

        let earliestRecordedSampleBuffer = backfillSampleBufferList.first!

        let _formatDescription = CMSampleBufferGetFormatDescription(earliestRecordedSampleBuffer)
        guard let formatDescription = _formatDescription else {
            print("Earliest recording pixel buffer format description was nil.")
            return
        }

        let videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo,
                                                  outputSettings: settingsAssistant.videoSettings,
                                                  sourceFormatHint: formatDescription)

        guard videoFileWriter.canAdd(videoWriterInput) else {
            print("Could not add video writer input to video file writer.")
            return
        }

        videoFileWriter.add(videoWriterInput)

        let pixelAdapterBufferAttributes = [ kCVPixelBufferPixelFormatTypeKey as String : Int(kCMPixelFormat_32BGRA) ]
        let pixelAdapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput,
                                                                sourcePixelBufferAttributes: pixelAdapterBufferAttributes)

        guard videoFileWriter.startWriting() else {
            print("Video file writer not ready to write file.")
            return
        }

        videoFileWriter.startSession(atSourceTime: CMSampleBufferGetOutputPresentationTimeStamp(earliestRecordedSampleBuffer))

        videoWriterInput.requestMediaDataWhenReady(on: recordingClipQueue) {
            while videoWriterInput.isReadyForMoreMediaData {
                if self.backfillSampleBufferList.count > 0 {
                    let sampleBufferToAppend = self.backfillSampleBufferList.first!.deepCopy()
                    let appendSampleBufferSucceeded = pixelAdapter.append(CMSampleBufferGetImageBuffer(sampleBufferToAppend)!,
                                                                          withPresentationTime: CMSampleBufferGetOutputPresentationTimeStamp(sampleBufferToAppend))
                    if !appendSampleBufferSucceeded {
                        print("Failed to append sample buffer to asset writer input: \(videoFileWriter.error!)")
                        print("Video file writer status: \(videoFileWriter.status.rawValue)")
                    }

                    self.backfillSampleBufferList.remove(at: 0)
                } else {
                    videoWriterInput.markAsFinished()
                    videoFileWriter.finishWriting {
                        print("Saving clip to \(clipURL)")
                    }

                    break
                }
            }
        }
    }

    // MARK: AVCaptureVideoDataOutputSampleBufferDelegate

    func captureOutput(_ captureOutput: AVCaptureOutput!,
                       didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
                       from connection: AVCaptureConnection!) {
        guard let buffer = sampleBuffer else {
            print("Captured sample buffer was nil.")
            return
        }

        let sampleBufferCopy = buffer.deepCopy()

        backfillSampleBufferList.append(sampleBufferCopy)

        if backfillSizeInSeconds() > 3.0 {
            session.stopRunning()
            createClipFromBackfill()
        }
    }

    func captureOutput(_ captureOutput: AVCaptureOutput!,
                       didDrop sampleBuffer: CMSampleBuffer!,
                       from connection: AVCaptureConnection!) {
        print("Sample buffer dropped.")
    }

}

Answer 3

在手动创建CVPixelBuffer和CMSampleBuffer以创建具有CoreGraphics呈现的各个帧的视频时，我遇到了相同错误代码的问题。 我可以通过使用AVAssetWriterInputPixelBufferAdaptor来解决问题，就像您在自己的答案中所建议的那样。 出于某种原因，只有在实际设备上运行代码时才需要这样做。 在模拟器上，手动创建缓冲区工作正常。

我注意到同样的错误代码AVFoundationErrorDomain Code -11800和NSOSStatusErrorDomain Code -12780也可能由于其他原因发生，例如：

• 在AVAssetWriter提供的目标URL处已存在文件
• 目标URL不是文件URL（必须使用URL.init(fileURLWithPath:)创建，而不是使用URL.init(string:) ）。

（为了完整起见，您的代码已正确处理此问题。）