Video scrubbing preview

2025-12-22 14:20:20 +00:00 · 2019-07-12 22:12:29 +04:00
parent 464738d8a8
commit baf2dbbb64
12 changed files with 708 additions and 6 deletions
--- a/submodules/MediaPlayer/Sources/MediaPlayerFramePreview.swift
+++ b/submodules/MediaPlayer/Sources/MediaPlayerFramePreview.swift
@@ -0,0 +1,131 @@
+import Foundation
+import SwiftSignalKit
+import Postbox
+import TelegramCore
+import FFMpeg
+
+private final class FramePreviewContext {
+    let source: UniversalSoftwareVideoSource
+    
+    init(source: UniversalSoftwareVideoSource) {
+        self.source = source
+    }
+}
+
+private func initializedPreviewContext(queue: Queue, postbox: Postbox, fileReference: FileMediaReference) -> Signal<QueueLocalObject<FramePreviewContext>, NoError> {
+    return Signal { subscriber in
+        let source = UniversalSoftwareVideoSource(mediaBox: postbox.mediaBox, fileReference: fileReference)
+        let readyDisposable = (source.ready
+        |> filter { $0 }).start(next: { _ in
+            subscriber.putNext(QueueLocalObject(queue: queue, generate: {
+                return FramePreviewContext(source: source)
+            }))
+        })
+        
+        return ActionDisposable {
+            readyDisposable.dispose()
+        }
+    }
+}
+
+private final class MediaPlayerFramePreviewImpl {
+    private let queue: Queue
+    private let context: Promise<QueueLocalObject<FramePreviewContext>>
+    private let currentFrameDisposable = MetaDisposable()
+    private var currentFrameTimestamp: Double?
+    private var nextFrameTimestamp: Double?
+    fileprivate let framePipe = ValuePipe<UIImage>()
+    
+    init(queue: Queue, postbox: Postbox, fileReference: FileMediaReference) {
+        self.queue = queue
+        self.context = Promise()
+        self.context.set(initializedPreviewContext(queue: queue, postbox: postbox, fileReference: fileReference))
+    }
+    
+    deinit {
+        assert(self.queue.isCurrent())
+        self.currentFrameDisposable.dispose()
+    }
+    
+    func generateFrame(at timestamp: Double) {
+        if self.currentFrameTimestamp != nil {
+            self.nextFrameTimestamp = timestamp
+            return
+        }
+        self.currentFrameTimestamp = timestamp
+        
+        let queue = self.queue
+        let takeDisposable = MetaDisposable()
+        let disposable = (self.context.get()
+        |> take(1)).start(next: { [weak self] context in
+            queue.async {
+                guard context.queue === queue else {
+                    return
+                }
+                context.with { context in
+                    let disposable = context.source.takeFrame(at: timestamp).start(next: { image in
+                        guard let strongSelf = self else {
+                            return
+                        }
+                        if let image = image {
+                            strongSelf.framePipe.putNext(image)
+                        }
+                        strongSelf.currentFrameTimestamp = nil
+                        if let nextFrameTimestamp = strongSelf.nextFrameTimestamp {
+                            strongSelf.nextFrameTimestamp = nil
+                            strongSelf.generateFrame(at: nextFrameTimestamp)
+                        }
+                    })
+                    takeDisposable.set(disposable)
+                }
+            }
+        })
+        self.currentFrameDisposable.set(ActionDisposable {
+            takeDisposable.dispose()
+            disposable.dispose()
+        })
+    }
+    
+    func cancelPendingFrames() {
+        self.nextFrameTimestamp = nil
+        self.currentFrameTimestamp = nil
+        self.currentFrameDisposable.set(nil)
+    }
+}
+
+public final class MediaPlayerFramePreview {
+    private let queue: Queue
+    private let impl: QueueLocalObject<MediaPlayerFramePreviewImpl>
+    
+    public var generatedFrames: Signal<UIImage?, NoError> {
+        return Signal { subscriber in
+            let disposable = MetaDisposable()
+            self.impl.with { impl in
+                disposable.set(impl.framePipe.signal().start(next: { image in
+                    subscriber.putNext(image)
+                }))
+            }
+            return disposable
+        }
+    }
+    
+    public init(postbox: Postbox, fileReference: FileMediaReference) {
+        let queue = Queue()
+        self.queue = queue
+        self.impl = QueueLocalObject(queue: queue, generate: {
+            return MediaPlayerFramePreviewImpl(queue: queue, postbox: postbox, fileReference: fileReference)
+        })
+    }
+    
+    public func generateFrame(at timestamp: Double) {
+        self.impl.with { impl in
+            impl.generateFrame(at: timestamp)
+        }
+    }
+    
+    public func cancelPendingFrames() {
+        self.impl.with { impl in
+            impl.cancelPendingFrames()
+        }
+    }
+}