Write chunks of video to memory and stream them in AVKit - swift

Question

I am making a file encryption app in Swift for iOS. I want to support video files using the stock, native system video player. I currently have code that does it well, but it falls short because of one issue - if the file is too big, the app fills the phone's memory. I wanna avoid that by streaming chunks of data to AVKit (NOT AVFoundation) and play the chunks while staying in the context of that single video. How do I do that?
Note: sending raw data IS possible with AVKit, I have found code that does it very nicely (you can pass data to an init() function that gets data and it is transformed into an AVPlayerItem. The code is complicated and I don't understand much of it, the only thing that I found is that it uses a custom URL and passes it to a normal AVPlayerItem and (I think) every time data is requested, it is being sent to that custom URL. The weirdest part is that I haven't set up ANY sort of custom URL scheme which is associated with my app's project file.
Here is the code for the Data to AVPlayerItem that I was talking about:
import Foundation
import AVFoundation
fileprivate extension URL {
func withScheme(_ scheme: String) -> URL? {
var components = URLComponents(url: self, resolvingAgainstBaseURL: false)
components?.scheme = scheme
return components?.url
}
}
#objc protocol CachingPlayerItemDelegate {
/// Is called when the media file is fully downloaded.
#objc optional func playerItem(_ playerItem: CachingPlayerItem, didFinishDownloadingData data: Data)
/// Is called every time a new portion of data is received.
#objc optional func playerItem(_ playerItem: CachingPlayerItem, didDownloadBytesSoFar bytesDownloaded: Int, outOf bytesExpected: Int)
/// Is called after initial prebuffering is finished, means
/// we are ready to play.
#objc optional func playerItemReadyToPlay(_ playerItem: CachingPlayerItem)
/// Is called when the data being downloaded did not arrive in time to
/// continue playback.
#objc optional func playerItemPlaybackStalled(_ playerItem: CachingPlayerItem)
/// Is called on downloading error.
#objc optional func playerItem(_ playerItem: CachingPlayerItem, downloadingFailedWith error: Error)
}
open class CachingPlayerItem: AVPlayerItem {
class ResourceLoaderDelegate: NSObject, AVAssetResourceLoaderDelegate, URLSessionDelegate, URLSessionDataDelegate, URLSessionTaskDelegate {
var playingFromData = false
var mimeType: String? // is required when playing from Data
var session: URLSession?
var mediaData: Data?
var response: URLResponse?
var pendingRequests = Set<AVAssetResourceLoadingRequest>()
weak var owner: CachingPlayerItem?
func resourceLoader(_ resourceLoader: AVAssetResourceLoader, shouldWaitForLoadingOfRequestedResource loadingRequest: AVAssetResourceLoadingRequest) -> Bool {
if playingFromData {
// Nothing to load.
} else if session == nil {
// If we're playing from a url, we need to download the file.
// We start loading the file on first request only.
guard let initialUrl = owner?.url else {
fatalError("internal inconsistency")
}
startDataRequest(with: initialUrl)
}
pendingRequests.insert(loadingRequest)
processPendingRequests()
return true
}
func startDataRequest(with url: URL) {
let configuration = URLSessionConfiguration.default
configuration.requestCachePolicy = .reloadIgnoringLocalAndRemoteCacheData
session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
session?.dataTask(with: url).resume()
}
func resourceLoader(_ resourceLoader: AVAssetResourceLoader, didCancel loadingRequest: AVAssetResourceLoadingRequest) {
pendingRequests.remove(loadingRequest)
}
// MARK: URLSession delegate
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
mediaData?.append(data)
processPendingRequests()
owner?.delegate?.playerItem?(owner!, didDownloadBytesSoFar: mediaData!.count, outOf: Int(dataTask.countOfBytesExpectedToReceive))
}
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: #escaping (URLSession.ResponseDisposition) -> Void) {
completionHandler(Foundation.URLSession.ResponseDisposition.allow)
mediaData = Data()
self.response = response
processPendingRequests()
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
if let errorUnwrapped = error {
owner?.delegate?.playerItem?(owner!, downloadingFailedWith: errorUnwrapped)
return
}
processPendingRequests()
owner?.delegate?.playerItem?(owner!, didFinishDownloadingData: mediaData!)
}
// MARK: -
func processPendingRequests() {
// get all fullfilled requests
let requestsFulfilled = Set<AVAssetResourceLoadingRequest>(pendingRequests.compactMap {
self.fillInContentInformationRequest($0.contentInformationRequest)
if self.haveEnoughDataToFulfillRequest($0.dataRequest!) {
$0.finishLoading()
return $0
}
return nil
})
// remove fulfilled requests from pending requests
_ = requestsFulfilled.map { self.pendingRequests.remove($0) }
}
func fillInContentInformationRequest(_ contentInformationRequest: AVAssetResourceLoadingContentInformationRequest?) {
// if we play from Data we make no url requests, therefore we have no responses, so we need to fill in contentInformationRequest manually
if playingFromData {
contentInformationRequest?.contentType = self.mimeType
contentInformationRequest?.contentLength = Int64(mediaData!.count)
contentInformationRequest?.isByteRangeAccessSupported = true
return
}
guard let responseUnwrapped = response else {
// have no response from the server yet
return
}
contentInformationRequest?.contentType = responseUnwrapped.mimeType
contentInformationRequest?.contentLength = responseUnwrapped.expectedContentLength
contentInformationRequest?.isByteRangeAccessSupported = true
}
func haveEnoughDataToFulfillRequest(_ dataRequest: AVAssetResourceLoadingDataRequest) -> Bool {
let requestedOffset = Int(dataRequest.requestedOffset)
let requestedLength = dataRequest.requestedLength
let currentOffset = Int(dataRequest.currentOffset)
guard let songDataUnwrapped = mediaData,
songDataUnwrapped.count > currentOffset else {
// Don't have any data at all for this request.
return false
}
let bytesToRespond = min(songDataUnwrapped.count - currentOffset, requestedLength)
let dataToRespond = songDataUnwrapped.subdata(in: Range(uncheckedBounds: (currentOffset, currentOffset + bytesToRespond)))
dataRequest.respond(with: dataToRespond)
return songDataUnwrapped.count >= requestedLength + requestedOffset
}
deinit {
session?.invalidateAndCancel()
}
}
fileprivate let resourceLoaderDelegate = ResourceLoaderDelegate()
fileprivate let url: URL
fileprivate let initialScheme: String?
fileprivate var customFileExtension: String?
weak var delegate: CachingPlayerItemDelegate?
open func download() {
if resourceLoaderDelegate.session == nil {
resourceLoaderDelegate.startDataRequest(with: url)
}
}
private let cachingPlayerItemScheme = "cachingPlayerItemScheme"
/// Is used for playing remote files.
convenience init(url: URL) {
self.init(url: url, customFileExtension: nil)
}
/// Override/append custom file extension to URL path.
/// This is required for the player to work correctly with the intended file type.
init(url: URL, customFileExtension: String?) {
guard let components = URLComponents(url: url, resolvingAgainstBaseURL: false),
let scheme = components.scheme,
var urlWithCustomScheme = url.withScheme(cachingPlayerItemScheme) else {
fatalError("Urls without a scheme are not supported")
}
self.url = url
self.initialScheme = scheme
if let ext = customFileExtension {
urlWithCustomScheme.deletePathExtension()
urlWithCustomScheme.appendPathExtension(ext)
self.customFileExtension = ext
}
let asset = AVURLAsset(url: urlWithCustomScheme)
asset.resourceLoader.setDelegate(resourceLoaderDelegate, queue: DispatchQueue.main)
super.init(asset: asset, automaticallyLoadedAssetKeys: nil)
resourceLoaderDelegate.owner = self
addObserver(self, forKeyPath: "status", options: NSKeyValueObservingOptions.new, context: nil)
NotificationCenter.default.addObserver(self, selector: #selector(playbackStalledHandler), name:NSNotification.Name.AVPlayerItemPlaybackStalled, object: self)
}
/// Is used for playing from Data.
init(data: Data, mimeType: String, fileExtension: String) {
guard let fakeUrl = URL(string: cachingPlayerItemScheme + "://whatever/file.\(fileExtension)") else {
fatalError("internal inconsistency")
}
self.url = fakeUrl
self.initialScheme = nil
resourceLoaderDelegate.mediaData = data
resourceLoaderDelegate.playingFromData = true
resourceLoaderDelegate.mimeType = mimeType
let asset = AVURLAsset(url: fakeUrl)
asset.resourceLoader.setDelegate(resourceLoaderDelegate, queue: DispatchQueue.main)
super.init(asset: asset, automaticallyLoadedAssetKeys: nil)
resourceLoaderDelegate.owner = self
addObserver(self, forKeyPath: "status", options: NSKeyValueObservingOptions.new, context: nil)
NotificationCenter.default.addObserver(self, selector: #selector(playbackStalledHandler), name:NSNotification.Name.AVPlayerItemPlaybackStalled, object: self)
}
// MARK: KVO
override open func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
delegate?.playerItemReadyToPlay?(self)
}
// MARK: Notification hanlers
#objc func playbackStalledHandler() {
delegate?.playerItemPlaybackStalled?(self)
}
// MARK: -
override init(asset: AVAsset, automaticallyLoadedAssetKeys: [String]?) {
fatalError("not implemented")
}
deinit {
NotificationCenter.default.removeObserver(self)
removeObserver(self, forKeyPath: "status")
resourceLoaderDelegate.session?.invalidateAndCancel()
}
}
I put it here in case anybody wants to use it. I didn't write this, this works was made by GitHub user "neekeetab". Here's the file.
If anyone can answer me about how to send AVKit a stream of data chunks that are inside of the iDevice's memory, I will be happy to hear from you. Even if you don't, thanks for stopping by!