Skip to content

Guard asset writer appends against unstarted and failed writers #45

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
tutis wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Guard asset writer appends against unstarted and failed writers #45

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions Azayaka/AppDelegate.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ class AppDelegate: NSObject, NSApplicationDelegate, SCStreamDelegate, SCStreamOu
var vwInput, awInput, micInput: AVAssetWriterInput!
let audioEngine = AVAudioEngine()
var startTime: Date?
var writerFailed = false

func applicationDidFinishLaunching(_ aNotification: Notification) {
lazy var userDesktop = (NSSearchPathForDirectoriesInDomains(.desktopDirectory, .userDomainMask, true) as [String]).first!
Expand Down
37 changes: 33 additions & 4 deletions Azayaka/ClassicProcessing.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,14 +6,18 @@
//

import ScreenCaptureKit
import OSLog

// This file contains code related to the "classic" recorder. It uses an
// AVAssetWriter instead of the ScreenCaptureKit recorder found in macOS Sequoia.
// System audio-only recording still uses this.

private let recordingLog = Logger(subsystem: "dev.mnpn.Azayaka", category: "recording")

extension AppDelegate {
func initClassicRecorder(conf: SCStreamConfiguration, encoder: AVVideoCodecType, filePath: String, fileType: AVFileType) {
startTime = nil
writerFailed = false

vW = try? AVAssetWriter.init(outputURL: URL(fileURLWithPath: filePath), fileType: fileType)
let fpsMultiplier: Double = Double(ud.integer(forKey: Preferences.kFrameRate))/8
Expand Down Expand Up @@ -55,7 +59,7 @@ extension AppDelegate {
if #unavailable(macOS 15), recordMic {
let input = audioEngine.inputNode
input.installTap(onBus: 0, bufferSize: 1024, format: input.inputFormat(forBus: 0)) { [self] (buffer, time) in
if micInput.isReadyForMoreMediaData && startTime != nil {
if canAppend(to: micInput) {
micInput.append(buffer.asSampleBuffer!)
}
}
Expand All @@ -81,7 +85,7 @@ extension AppDelegate {
startTime = Date.now
vW.startSession(atSourceTime: CMSampleBufferGetPresentationTimeStamp(sampleBuffer))
}
if vwInput.isReadyForMoreMediaData {
if canAppend(to: vwInput) {
vwInput.append(sampleBuffer)
}
break
Expand All @@ -93,20 +97,45 @@ extension AppDelegate {
}
catch { assertionFailure("audio file writing issue".local) }
} else { // otherwise send the audio data to AVAssetWriter
if (awInput != nil) && awInput.isReadyForMoreMediaData {
if canAppend(to: awInput) {
awInput.append(sampleBuffer)
}
}
case .microphone: // only available on sequoia - older versions will use AVAudioEngine
if streamType != .systemaudio {
if (micInput != nil) && micInput.isReadyForMoreMediaData {
if canAppend(to: micInput) {
micInput.append(sampleBuffer)
}
}
@unknown default:
assertionFailure("unknown stream type".local)
}
}

// AVAssetWriterInput.append() raises an Objective-C exception, which Swift is unable to catch, if
// the writer has not started a session or has already failed. isReadyForMoreMediaData reports
// neither of those states, so both are checked here before appending to any input. Audio buffers
// may arrive before the first video frame has started the session, and the writer can fail at any
// point during a recording, so without this an append would terminate the whole app.
func canAppend(to input: AVAssetWriterInput!) -> Bool {
guard let vW = vW, input != nil, startTime != nil else { return false }
guard vW.status == .writing else {
if vW.status == .failed { handleWriterFailure(vW.error) }
return false
}
return input.isReadyForMoreMediaData
}

// A failed writer will never accept another sample, so the recording is stopped rather than left
// running while silently dropping everything.
func handleWriterFailure(_ error: Error?) {
guard !writerFailed else { return } // buffers keep arriving until the stream actually stops
writerFailed = true
recordingLog.error("The asset writer failed, stopping the recording: \(error?.localizedDescription ?? "unknown error", privacy: .public)")
DispatchQueue.main.async { [self] in
stopRecording(withError: true) // this stops the capture and finalises the file
}
}
}

// https://developer.apple.com/documentation/screencapturekit/capturing_screen_content_in_macos
Expand Down