UIView to CMSampleBuffer (UIViewをCMSampleBufferに変換するExtension)

toCMSampleBuffer.swift

import UIKit
import CoreMedia

extension UIView {
    func toCMSampleBuffer() -> CMSampleBuffer? {
        let scale: CGFloat = UIScreen.main.scale
        let size: CGSize = .init(width: bounds.width * scale, height: bounds.height * scale)
        guard let pixelBuffer = makeCVPicelBuffer(scale: scale, size: size) else { return nil }
        defer {
            CVPixelBufferUnlockBaseAddress(pixelBuffer,  CVPixelBufferLockFlags(rawValue: 0))
        }
        CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))

        guard let context = makeCGContext(scale: scale, size: size, pixelBuffer: pixelBuffer) else { return nil }
        layer.render(in: context)

        guard let formatDescription = makeCMFormatDescription(pixelBuffer: pixelBuffer) else { return nil }

        do {
            return try CMSampleBuffer(
                imageBuffer: pixelBuffer,
                formatDescription: formatDescription,
                sampleTiming: getCMSampleTimingInfo()
            )
        } catch {
            assertionFailure("Failed to create CMSampleBuffer: \(error)")
            return nil
        }
    }

    private func makeCVPicelBuffer(scale: CGFloat, size: CGSize) -> CVPixelBuffer? {
        var pixelBuffer: CVPixelBuffer?
        let createPixelBufferResult: CVReturn = CVPixelBufferCreate(
            kCFAllocatorDefault,
            Int(size.width),
            Int(size.height),
            kCVPixelFormatType_32ARGB,
            [
                kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue!,
                kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue!,
                kCVPixelBufferIOSurfacePropertiesKey: [:] as CFDictionary,
            ] as CFDictionary,
            &pixelBuffer
        )

        if createPixelBufferResult != kCVReturnSuccess {
            assertionFailure("Failed to create CVPixelBuffer: \(createPixelBufferResult)")
            return nil
        }

        return pixelBuffer
    }

    private func makeCGContext(scale: CGFloat, size: CGSize, pixelBuffer: CVPixelBuffer) -> CGContext? {
        guard let context: CGContext = .init(
            data: CVPixelBufferGetBaseAddress(pixelBuffer),
            width: Int(size.width),
            height: Int(size.height),
            bitsPerComponent: 8,
            bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer),
            space: CGColorSpaceCreateDeviceRGB(),
            bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue
        ) else { return nil }

        context.translateBy(x: 0, y: size.height)
        context.scaleBy(x: scale, y: -scale)
        return context
    }

    private func makeCMFormatDescription(pixelBuffer: CVPixelBuffer) -> CMFormatDescription? {
        var formatDescription: CMFormatDescription?
        let createImageBufferResult: CVReturn = CMVideoFormatDescriptionCreateForImageBuffer(
            allocator: kCFAllocatorDefault,
            imageBuffer: pixelBuffer,
            formatDescriptionOut: &formatDescription
        )

        if createImageBufferResult != kCVReturnSuccess {
            assertionFailure("Failed to create CMFormatDescription: \(createImageBufferResult)")
            return nil
        }

        return formatDescription
    }

    private func getCMSampleTimingInfo() -> CMSampleTimingInfo {
        let currentTime: CMTime = .init(
            seconds: CACurrentMediaTime(),
            preferredTimescale: 60
        )

        let timingInfo: CMSampleTimingInfo = .init(
            duration: .init(seconds: 1, preferredTimescale: 60),
            presentationTimeStamp: currentTime,
            decodeTimeStamp: currentTime
        )

        return timingInfo
    }
}

hi, thanks for usefull gist. Did you tried to apply webrtc call with PIP mode?

This was very helpful - domo arigato!