fix: 视频只有一帧 + 音频长度不对

视频修复:
- 移除 hasNewPixelBuffer 依赖，改为缓存 lastPixelBuffer
- 每 1/30s 始终写入帧（新帧或复用上一帧），确保静态场景也持续输出
- 加 isRunning 检查防止停止后继续写入

音频修复:
- 用 requestMediaDataWhenReady 替代 busy-loop
- writer 控制读取节奏，不再一次性读完全部源音频
- stopRecording 时 cancelReading + markAsFinished 立即停止

音视频同步:
- 视频用 itemTime 相对 firstFrameTime 的时间戳
- 音频用源文件 pts 相对 firstFrameTime 的时间戳
- 两者共享同一时间基准

Sources/PlayerBridge.swift

@@ -122,7 +122,8 @@ final class PlayerBridge: ObservableObject {
             }
             guard !queue.isEmpty else { return }
             let sourceURL = queue[currentIndex].url
-            screenRecorder.startRecording(from: output, sourceURL: sourceURL)
+            let startTime = player.currentTime()
+            screenRecorder.startRecording(from: output, sourceURL: sourceURL, startTime: startTime)
         }
         #endif
     }

Sources/PlayerRecorder.swift

@@ -17,14 +17,10 @@ final class PlayerRecorder: NSObject {
     private var audioReaderOutput: AVAssetReaderTrackOutput?
     private var audioCaptureQueue: DispatchQueue?
     private var isRunning = false
-    /// 线程安全的音频停止标志，后台队列直接读取
-    nonisolated(unsafe) private var audioStopped: Bool = false
-    /// 音频线程读取 firstFrameTime 的镜像
-    nonisolated(unsafe) private var audioFirstFrameTime: CMTime?
     
-    // 音频预加载状态
+    // 视频：缓存上一帧，确保静态场景也能持续写入
-    private var pendingAudioAsset: AVURLAsset?
+    private var lastPixelBuffer: CVPixelBuffer?
-    private var pendingAudioTrack: AVAssetTrack?
+    private var captureFrameCount: Int = 0
     
     @Published var isRecording = false
     @Published var durationText = "00:00"
@@ -42,13 +38,14 @@ final class PlayerRecorder: NSObject {
     }
     
     /// 开始录制
-    func startRecording(from output: AVPlayerItemVideoOutput, sourceURL: URL) {
+    func startRecording(from output: AVPlayerItemVideoOutput, sourceURL: URL, startTime: CMTime) {
         guard !isRecording else { return }
         
         weakOutput = output
         firstFrameTime = nil
+        lastPixelBuffer = nil
+        captureFrameCount = 0
         isRunning = false
-        audioStopped = false
         
         // 临时文件
         let formatter = DateFormatter()
@@ -97,12 +94,12 @@ final class PlayerRecorder: NSObject {
         
         // 启动视频抓帧
         isRecording = true
-        isRunning = true  // 必须在 startCaptureLoop 之前设置
+        isRunning = true
         startTimer()
         startCaptureLoop()
         
-        // 准备音频读取（等待 firstFrameTime 后才真正开始）
+        // 启动音频读取（从播放位置开始）
-        prepareAudioCapture(sourceURL: sourceURL)
+        startAudioCapture(sourceURL: sourceURL, startTime: startTime, audioWriterInput: aInput)
     }
     
     /// 停止录制
@@ -113,7 +110,11 @@ final class PlayerRecorder: NSObject {
         captureTimer?.invalidate()
         captureTimer = nil
         stopTimer()
-        stopAudioCapture()
+        
+        // 停止音频：先 cancel reader，再 markAsFinished
+        audioReader?.cancelReading()
+        audioReader = nil
+        audioReaderOutput = nil
         
         videoInput?.markAsFinished()
         audioInput?.markAsFinished()
@@ -126,13 +127,14 @@ final class PlayerRecorder: NSObject {
                 }
             }
         }
+        
+        lastPixelBuffer = nil
     }
     
     // MARK: - 视频抓帧
     private var captureTimer: Timer?
     
     private func startCaptureLoop() {
-        // 用 Timer 每 1/30 秒抓一帧
         captureTimer = Timer.scheduledTimer(withTimeInterval: 1.0 / 30.0, repeats: true) { [weak self] _ in
             Task { @MainActor in
                 self?.captureVideoFrame()
@@ -141,33 +143,34 @@ final class PlayerRecorder: NSObject {
     }
     
     private func captureVideoFrame() {
-        guard let output = weakOutput, let input = videoInput, input.isReadyForMoreMediaData else { return }
+        guard isRunning, let output = weakOutput, let input = videoInput,
+              input.isReadyForMoreMediaData else { return }
         
         let hostTime = CACurrentMediaTime()
         let itemTime = output.itemTime(forHostTime: hostTime)
         
-        guard output.hasNewPixelBuffer(forItemTime: itemTime),
+        // 尝试获取新帧，否则复用上一帧（确保静态场景也持续写入）
-              let pb = output.copyPixelBuffer(forItemTime: itemTime, itemTimeForDisplay: nil) else { return }
+        if let pb = output.copyPixelBuffer(forItemTime: itemTime, itemTimeForDisplay: nil) {
-        
+            lastPixelBuffer = pb
-        // 第一帧：用它的时间作为 session 起点
+        }
-        if firstFrameTime == nil {
+        
-            firstFrameTime = itemTime
+        guard let pb = lastPixelBuffer else { return }
-            audioFirstFrameTime = itemTime  // 同步给音频线程
+        
-            writer?.startSession(atSourceTime: itemTime)
+        // 第一帧：启动 session
-            isRunning = true
+        if firstFrameTime == nil {
-            // 音频预加载完成后，用 firstFrameTime 作为起始时间开始读取
+            firstFrameTime = itemTime
-            beginAudioReading(startTime: itemTime)
+            writer?.startSession(atSourceTime: itemTime)
         }
         
-        // 相对时间戳
         guard let firstTime = firstFrameTime else { return }
         let relativeTime = CMTimeSubtract(itemTime, firstTime)
-        
         guard relativeTime.seconds >= 0 else { return }
         
         let sampleBuffer = Self.createSampleBuffer(from: pb, time: relativeTime)
         if let sb = sampleBuffer {
-            _ = input.append(sb)
+            if input.append(sb) {
+                captureFrameCount += 1
+            }
         }
     }
     
@@ -187,13 +190,9 @@ final class PlayerRecorder: NSObject {
         return sampleBuffer
     }
     
-    // MARK: - 音频读取（从源 URL）
+    // MARK: - 音频读取（从源 URL，用 requestMediaDataWhenReady 控制节奏）
-    
+    private func startAudioCapture(sourceURL: URL, startTime: CMTime, audioWriterInput: AVAssetWriterInput) {
-    /// 预加载音频轨道（异步），不立即开始读取
-    private func prepareAudioCapture(sourceURL: URL) {
         let asset = AVURLAsset(url: sourceURL)
-        pendingAudioAsset = asset
-        pendingAudioTrack = nil
         
         Task {
             do {
@@ -202,84 +201,65 @@ final class PlayerRecorder: NSObject {
                     print("[Recorder] No audio track in source")
                     return
                 }
-                self.pendingAudioTrack = audioTrack
+                guard self.isRunning else { return }
-                // 如果 firstFrameTime 已经设置好了，立即开始读取
+                
-                if let fft = self.firstFrameTime {
+                let reader = try AVAssetReader(asset: asset)
-                    self.beginAudioReading(startTime: fft)
+                let readerOutput = AVAssetReaderTrackOutput(track: audioTrack, outputSettings: [
+                    AVFormatIDKey: kAudioFormatLinearPCM,
+                    AVSampleRateKey: 44100,
+                    AVNumberOfChannelsKey: 2,
+                    AVLinearPCMBitDepthKey: 16,
+                    AVLinearPCMIsFloatKey: false,
+                    AVLinearPCMIsBigEndianKey: false,
+                    AVLinearPCMIsNonInterleaved: false
+                ])
+                readerOutput.alwaysCopiesSampleData = false
+                
+                // 从播放位置开始读取
+                reader.timeRange = CMTimeRange(start: startTime, duration: .positiveInfinity)
+                
+                if reader.canAdd(readerOutput) {
+                    reader.add(readerOutput)
+                    reader.startReading()
+                    
+                    self.audioReader = reader
+                    self.audioReaderOutput = readerOutput
+                    
+                    // 用 requestMediaDataWhenReady 控制读取节奏（writer 需要数据时才读）
+                    let queue = DispatchQueue(label: "recorder.audio.capture")
+                    self.audioCaptureQueue = queue
+                    
+                    audioWriterInput.requestMediaDataWhenReady(on: queue) { [weak self] in
+                        guard let self = self else { return }
+                        self.feedAudioSamples(writerInput: audioWriterInput, readerOutput: readerOutput, reader: reader)
+                    }
                 }
             } catch {
-                print("[Recorder] Audio track load failed: \(error)")
+                print("[Recorder] Audio capture setup failed: \(error)")
             }
         }
     }
     
-    /// 用 firstFrameTime 作为起始时间，创建 reader 并开始后台读取
+    /// 由 requestMediaDataWhenReady 回调，writer 需要数据时才读取
-    private func beginAudioReading(startTime: CMTime) {
+    private func feedAudioSamples(writerInput: AVAssetWriterInput,
-        guard let asset = pendingAudioAsset, let audioTrack = pendingAudioTrack else {
+                                   readerOutput: AVAssetReaderTrackOutput,
-            return  // 轨道还没加载好，prepareAudioCapture 的回调会再次调用
+                                   reader: AVAssetReader) {
-        }
+        while writerInput.isReadyForMoreMediaData {
-        guard let aInput = audioInput else { return }
+            guard isRunning, reader.status == .reading,
-        // 防止重复启动
+                  let sampleBuffer = readerOutput.copyNextSampleBuffer() else {
-        guard audioReader == nil else { return }
+                // 录制已停止或读取完毕
-        
+                if isRunning {
-        do {
+                    writerInput.markAsFinished()
-            let reader = try AVAssetReader(asset: asset)
-            let output = AVAssetReaderTrackOutput(track: audioTrack, outputSettings: [
-                AVFormatIDKey: kAudioFormatLinearPCM,
-                AVSampleRateKey: 44100,
-                AVNumberOfChannelsKey: 2,
-                AVLinearPCMBitDepthKey: 16,
-                AVLinearPCMIsFloatKey: false,
-                AVLinearPCMIsBigEndianKey: false,
-                AVLinearPCMIsNonInterleaved: false
-            ])
-            output.alwaysCopiesSampleData = false
-            
-            // 从视频第一帧时间开始读取，确保音视频同步
-            reader.timeRange = CMTimeRange(start: startTime, duration: .positiveInfinity)
-            
-            if reader.canAdd(output) {
-                reader.add(output)
-                reader.startReading()
-                
-                self.audioReader = reader
-                self.audioReaderOutput = output
-                
-                // 后台线程读取音频
-                let queue = DispatchQueue(label: "recorder.audio.capture")
-                self.audioCaptureQueue = queue
-                queue.async { [weak self] in
-                    guard let self = self else { return }
-                    self.readAudioLoop(reader: reader, output: output, audioInput: aInput)
                 }
-            }
+                return
-        } catch {
-            print("[Recorder] Audio capture setup failed: \(error)")
-        }
-        
-        // 清理预加载状态
-        pendingAudioAsset = nil
-        pendingAudioTrack = nil
-    }
-    
-    private nonisolated func readAudioLoop(reader: AVAssetReader, output: AVAssetReaderTrackOutput, audioInput: AVAssetWriterInput) {
-        while !audioStopped && reader.status == .reading {
-            guard let sampleBuffer = output.copyNextSampleBuffer() else {
-                break
             }
             
-            // 直接在后台队列处理，不走 MainActor（避免队列积压）
+            // 重映射时间戳：源文件时间 → 相对于录制开始的时间
-            guard let firstTime = audioFirstFrameTime else {
+            guard let firstTime = self.firstFrameTime else {
-                // 视频第一帧还没到，跳过这个音频 buffer
+                // 视频第一帧还没到，丢弃这个 buffer
                 continue
             }
-            guard audioInput.isReadyForMoreMediaData else { continue }
             
-            let pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
-            let relativeTime = CMTimeSubtract(pts, firstTime)
-            guard relativeTime.seconds >= 0 else { continue }
-            
-            // 重建 sample buffer with new time
             var count: CMItemCount = 0
             CMSampleBufferGetSampleTimingInfoArray(sampleBuffer, entryCount: 0, arrayToFill: nil, entriesNeededOut: &count)
             var timingInfo = [CMSampleTimingInfo](repeating: CMSampleTimingInfo(), count: count)
@@ -294,18 +274,13 @@ final class PlayerRecorder: NSObject {
             CMSampleBufferCreateCopyWithNewTiming(allocator: kCFAllocatorDefault, sampleBuffer: sampleBuffer, sampleTimingEntryCount: count, sampleTimingArray: &timingInfo, sampleBufferOut: &newBuffer)
             
             if let nb = newBuffer {
-                _ = audioInput.append(nb)
+                if !writerInput.append(nb) {
+                    return
+                }
             }
         }
     }
     
-    private func stopAudioCapture() {
-        audioStopped = true          // 先设标志，loop 立即退出
-        audioReader?.cancelReading()
-        audioReader = nil
-        audioReaderOutput = nil
-    }
-    
     // MARK: - Timer
     private func startTimer() {
         startDate = Date()