Files
openscreen/electron/native/screencapturekit/Sources/OpenScreenScreenCaptureKitHelper/main.swift
T
2026-05-18 12:19:05 +02:00

356 lines
9.0 KiB
Swift

import AVFoundation
import CoreMedia
import Foundation
import ScreenCaptureKit
struct Rectangle: Decodable {
let x: Double
let y: Double
let width: Double
let height: Double
}
struct RecordingRequest: Decodable {
struct Source: Decodable {
let type: String
let sourceId: String
let displayId: UInt32?
let windowId: UInt32?
let bounds: Rectangle?
}
struct Video: Decodable {
let fps: Int
let width: Int
let height: Int
let bitrate: Int?
let hideSystemCursor: Bool
}
struct Audio: Decodable {
struct SystemAudio: Decodable {
let enabled: Bool
}
struct Microphone: Decodable {
let enabled: Bool
let deviceId: String?
let deviceName: String?
let gain: Double
}
let system: SystemAudio
let microphone: Microphone
}
struct Webcam: Decodable {
let enabled: Bool
let deviceId: String?
let deviceName: String?
let width: Int
let height: Int
let fps: Int
}
struct Cursor: Decodable {
let mode: String
}
struct Outputs: Decodable {
let screenPath: String
let manifestPath: String?
}
let schemaVersion: Int?
let recordingId: Int?
let source: Source
let video: Video
let audio: Audio
let webcam: Webcam
let cursor: Cursor
let outputs: Outputs
}
enum HelperError: Error, CustomStringConvertible {
case invalidArguments
case unsupportedMacOS
case unsupportedFeature(String)
case sourceNotFound(String)
case invalidSourceType(String)
case writerSetupFailed(String)
var description: String {
switch self {
case .invalidArguments:
return "Expected one JSON recording request argument."
case .unsupportedMacOS:
return "ScreenCaptureKit recording requires macOS 13 or newer."
case .unsupportedFeature(let message):
return message
case .sourceNotFound(let message):
return message
case .invalidSourceType(let sourceType):
return "Unsupported source type: \(sourceType)."
case .writerSetupFailed(let message):
return message
}
}
}
func emit(_ fields: [String: Any]) {
if let data = try? JSONSerialization.data(withJSONObject: fields, options: []),
let line = String(data: data, encoding: .utf8)
{
print(line)
fflush(stdout)
}
}
func emitError(code: String, message: String) {
emit([
"event": "error",
"code": code,
"message": message,
])
}
@available(macOS 13.0, *)
final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
private let request: RecordingRequest
private let sampleQueue = DispatchQueue(label: "app.openscreen.sck-helper.samples")
private let stateQueue = DispatchQueue(label: "app.openscreen.sck-helper.state")
private var stream: SCStream?
private var writer: AVAssetWriter?
private var videoInput: AVAssetWriterInput?
private var didStartWriting = false
private var isStopping = false
init(request: RecordingRequest) {
self.request = request
}
func start() async throws {
try rejectUnsupportedPhaseFeatures()
let content = try await SCShareableContent.excludingDesktopWindows(
false,
onScreenWindowsOnly: true
)
let filter = try makeContentFilter(from: content)
let configuration = makeStreamConfiguration()
let stream = SCStream(filter: filter, configuration: configuration, delegate: self)
try stream.addStreamOutput(self, type: .screen, sampleHandlerQueue: sampleQueue)
try setupWriter()
self.stream = stream
emit(["event": "ready", "schemaVersion": 1])
try await stream.startCapture()
emit([
"event": "recording-started",
"timestampMs": Int(Date().timeIntervalSince1970 * 1000),
])
}
func stop() async {
let shouldStop = stateQueue.sync {
if isStopping {
return false
}
isStopping = true
return true
}
if !shouldStop {
return
}
do {
try await stream?.stopCapture()
} catch {
emit([
"event": "warning",
"code": "stop-capture-failed",
"message": "\(error)",
])
}
await finishWriter()
}
func stream(_ stream: SCStream, didStopWithError error: Error) {
emitError(code: "capture-stopped-with-error", message: "\(error)")
Task {
await stop()
}
}
func stream(_ stream: SCStream, didOutputSampleBuffer sampleBuffer: CMSampleBuffer, of type: SCStreamOutputType) {
guard type == .screen else {
return
}
guard CMSampleBufferDataIsReady(sampleBuffer) else {
return
}
guard let videoInput, let writer else {
return
}
let presentationTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
if !didStartWriting {
writer.startWriting()
writer.startSession(atSourceTime: presentationTime)
didStartWriting = true
}
if videoInput.isReadyForMoreMediaData {
videoInput.append(sampleBuffer)
}
}
private func rejectUnsupportedPhaseFeatures() throws {
if request.audio.system.enabled {
throw HelperError.unsupportedFeature(
"System audio capture is planned for the roadmap system-audio phase."
)
}
if request.audio.microphone.enabled {
throw HelperError.unsupportedFeature(
"Microphone capture is planned for the roadmap microphone phase."
)
}
if request.webcam.enabled {
throw HelperError.unsupportedFeature(
"Webcam composition is planned for the roadmap webcam phase."
)
}
}
private func makeContentFilter(from content: SCShareableContent) throws -> SCContentFilter {
switch request.source.type {
case "display":
guard let displayId = request.source.displayId else {
throw HelperError.sourceNotFound("Display capture requires source.displayId.")
}
guard let display = content.displays.first(where: { $0.displayID == displayId }) else {
throw HelperError.sourceNotFound("No ScreenCaptureKit display found for id \(displayId).")
}
return SCContentFilter(display: display, excludingWindows: [])
case "window":
guard let windowId = request.source.windowId else {
throw HelperError.sourceNotFound("Window capture requires source.windowId.")
}
guard let window = content.windows.first(where: { $0.windowID == windowId }) else {
throw HelperError.sourceNotFound("No ScreenCaptureKit window found for id \(windowId).")
}
return SCContentFilter(desktopIndependentWindow: window)
default:
throw HelperError.invalidSourceType(request.source.type)
}
}
private func makeStreamConfiguration() -> SCStreamConfiguration {
let configuration = SCStreamConfiguration()
configuration.width = request.video.width
configuration.height = request.video.height
configuration.minimumFrameInterval = CMTime(value: 1, timescale: CMTimeScale(max(1, request.video.fps)))
configuration.queueDepth = 6
configuration.showsCursor = !request.video.hideSystemCursor
configuration.pixelFormat = kCVPixelFormatType_32BGRA
return configuration
}
private func setupWriter() throws {
let outputUrl = URL(fileURLWithPath: request.outputs.screenPath)
try? FileManager.default.removeItem(at: outputUrl)
try FileManager.default.createDirectory(
at: outputUrl.deletingLastPathComponent(),
withIntermediateDirectories: true
)
let writer = try AVAssetWriter(outputURL: outputUrl, fileType: .mp4)
let settings: [String: Any] = [
AVVideoCodecKey: AVVideoCodecType.h264,
AVVideoWidthKey: request.video.width,
AVVideoHeightKey: request.video.height,
AVVideoCompressionPropertiesKey: [
AVVideoAverageBitRateKey: request.video.bitrate ?? 18_000_000,
AVVideoExpectedSourceFrameRateKey: request.video.fps,
],
]
let input = AVAssetWriterInput(mediaType: .video, outputSettings: settings)
input.expectsMediaDataInRealTime = true
guard writer.canAdd(input) else {
throw HelperError.writerSetupFailed("Unable to add H.264 video input to AVAssetWriter.")
}
writer.add(input)
self.writer = writer
self.videoInput = input
}
private func finishWriter() async {
guard let writer else {
return
}
videoInput?.markAsFinished()
await withCheckedContinuation { continuation in
writer.finishWriting {
continuation.resume()
}
}
if writer.status == .completed {
emit([
"event": "recording-stopped",
"screenPath": request.outputs.screenPath,
])
} else {
emitError(
code: "writer-failed",
message: writer.error.map { "\($0)" } ?? "AVAssetWriter failed with status \(writer.status.rawValue)."
)
}
}
}
@main
struct OpenScreenScreenCaptureKitHelper {
static func main() async {
do {
guard CommandLine.arguments.count == 2 else {
throw HelperError.invalidArguments
}
guard #available(macOS 13.0, *) else {
throw HelperError.unsupportedMacOS
}
let requestData = Data(CommandLine.arguments[1].utf8)
let decoder = JSONDecoder()
let request = try decoder.decode(RecordingRequest.self, from: requestData)
let recorder = ScreenCaptureRecorder(request: request)
let stopTask = Task.detached {
while let line = readLine() {
let command = line.trimmingCharacters(in: .whitespacesAndNewlines)
if command == "stop" {
await recorder.stop()
exit(0)
}
}
}
try await recorder.start()
await stopTask.value
} catch let error as HelperError {
emitError(code: "helper-error", message: error.description)
exit(1)
} catch {
emitError(code: "helper-error", message: "\(error)")
exit(1)
}
}
}