How to save video asynchronously?

could you post a snippet of your exact code that you're referencing? Have you looked into the "Concurrency Note" on this page which details the ins and outs of async calls? https://developer.apple.com/documentation/photokit/phphotolibrary/1620743-performchanges

Hello,

I'm putting an audio of AVSpeechSynthesizer.write() in a video and some photos.

I tried to put a very long text, to the point of having made a video of around 50 minutes. When saving the video to the gallery, the APP would freeze until it was saved. In other cases, the APP would crash and I would have to compile again.

I tried to use PHPhotoLibrary.shared().performChanges() instead of UISaveVideoAtPathToSavedPhotosAlbum . But the APP would crash until you saved the video to the gallery or the APP it crashed and wouldn't come back.

Here's the code:

private let synthesizer = AVSpeechSynthesizer()
private var counterImage = 0

let semaphore = DispatchSemaphore(value: 0)

init(_ texts: [String]) {
Misc.obj.lData.removeAll()
Misc.obj.selectedPhotos.append(createBlueImage(CGSize(width: 100, height: 100)))
Misc.obj.selectedPhotos.append(createBlueImage(CGSize(width: 100, height: 100)))
super.init()
synthesizer.delegate = self

DispatchQueue.global().async {
do {
try self.nextText(texts)
msgErro("Completed.")
} catch {
msgErro(error.localizedDescription)
}
}
}

func nextText(_ texts: [String]) throws {
var audioBuffers = [CMSampleBuffer]()
var videoBuffers = [CVPixelBuffer]()
var lTime = [0.0]

for text in texts {
var time = Double.zero
var duration = AVAudioFrameCount.zero

let utterance = AVSpeechUtterance(string: texto)
utterance.voice = AVSpeechSynthesisVoice(language: "pt-BR")
utterance.rate = 0.2

synthesizer.write(utterance) { buffer in
if let buffer = buffer as? AVAudioPCMBuffer, let sampleBuffer = buffer.toCMSampleBuffer(presentationTime: .zero) {
audioBuffers.append(sampleBuffer)
duration += buffer.frameLength
time += Double(buffer.frameLength) / buffer.format.sampleRate
}
}

semaphore.wait()

if Misc.obj.selectedPhotos.indices.contains(contadorImagem) {
let image = Misc.obj.selectedPhotos[counterImage]
//let imagemEscrita = imagem.addTexto(textos[quantTxt])
let pixelBuffer = image.toCVPixelBuffer()
videoBuffers.append(pixelBuffer!)
lTime.append(time)

// Increase counterImage
counterImage += 1

if counterImage == Misc.obj.selectedPhotos.count {
counterImage = 0
}
}
}

let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("*****/output.mp4")
try FileManager.default.createDirectory(at: url.deletingLastPathComponent(), withIntermediateDirectories: true)

if FileManager.default.fileExists(atPath: url.path()) {
try FileManager.default.removeItem(at: url)
}

let audioProvider = SampleProvider(buffers: audioBuffers)
let videoProvider = SampleProvider(buffers: videoBuffers, lTempo: lTempo)

let audioInput = createAudioInput(audioBuffers: audioBuffers)
let videoInput = createVideoInput(videoBuffers: videoBuffers)
let adaptor = createPixelBufferAdaptor(videoInput: videoInput)

let assetWriter = try AVAssetWriter(outputURL: url, fileType: .mp4)
assetWriter.add(videoInput)
assetWriter.add(audioInput)
assetWriter.startWriting()
assetWriter.startSession(atSourceTime: .zero)

let writerQueue = DispatchQueue(label: "Asset Writer Queue")

videoInput.requestMediaDataWhenReady(on: writerQueue) {
if let buffer = videoProvider.getNextBuffer() {
adaptor.append(buffer, withPresentationTime: videoProvider.getPresentationTime())
} else {
videoInput.markAsFinished()

if audioProvider.isFinished() {
self.semaphore.signal()
}
}
}

audioInput.requestMediaDataWhenReady(on: writerQueue) {
if let buffer = audioProvider.getNextBuffer() {
audioInput.append(buffer)
} else {
audioInput.markAsFinished()

if audioProvider.isFinished() {
self.semaphore.signal()
}
}
}

semaphore.wait()

assetWriter.finishWriting {
switch assetWriter.status {
case .completed:
msgRelatos("Completed.")
UISaveVideoAtPathToSavedPhotosAlbum(url.path, nil, nil, nil)
case .failed:
if let error = assetWriter.error {
msgErro("Error: \(error.localizedDescription)")
} else {
msgRelatos("No recorded.")
}
default:
msgRelatos("Error not found.")
}
}
}
}

extension TesteFala: AVSpeechSynthesizerDelegate {
func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didFinish utterance: AVSpeechUtterance) {
semaphore.signal()
}
}