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
This commit is contained in:
yumoqing 2026-06-24 21:19:10 +08:00
parent 42f3cf2b84
commit 06345b07de
2 changed files with 86 additions and 110 deletions

View File

@ -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
}

View File

@ -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
private var pendingAudioAsset: AVURLAsset?
private var pendingAudioTrack: AVAssetTrack?
// 视频:缓存上一帧,确保静态场景也能持续写入
private var lastPixelBuffer: CVPixelBuffer?
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)
prepareAudioCapture(sourceURL: sourceURL)
// 启动音频读取(从播放位置开始)
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),
let pb = output.copyPixelBuffer(forItemTime: itemTime, itemTimeForDisplay: nil) else { return }
// 第一帧:用它的时间作为 session 起点
if firstFrameTime == nil {
firstFrameTime = itemTime
audioFirstFrameTime = itemTime // 同步给音频线程
writer?.startSession(atSourceTime: itemTime)
isRunning = true
// 音频预加载完成后,用 firstFrameTime 作为起始时间开始读取
beginAudioReading(startTime: 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)
if let pb = output.copyPixelBuffer(forItemTime: itemTime, itemTimeForDisplay: nil) {
lastPixelBuffer = pb
}
guard let pb = lastPixelBuffer else { return }
// 第一帧:启动 session
if firstFrameTime == nil {
firstFrameTime = 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)
/// 预加载音频轨道(异步),不立即开始读取
private func prepareAudioCapture(sourceURL: URL) {
// MARK: - 音频读取(从源 URL,用 requestMediaDataWhenReady 控制节奏)
private func startAudioCapture(sourceURL: URL, startTime: CMTime, audioWriterInput: AVAssetWriterInput) {
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
// 如果 firstFrameTime 已经设置好了,立即开始读取
if let fft = self.firstFrameTime {
self.beginAudioReading(startTime: fft)
guard self.isRunning else { return }
let reader = try AVAssetReader(asset: asset)
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
private func beginAudioReading(startTime: CMTime) {
guard let asset = pendingAudioAsset, let audioTrack = pendingAudioTrack else {
return // 轨道还没加载好,prepareAudioCapture 的回调会再次调用
}
guard let aInput = audioInput else { return }
// 防止重复启动
guard audioReader == nil else { return }
do {
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)
/// 由 requestMediaDataWhenReady 回调,writer 需要数据时才读取
private func feedAudioSamples(writerInput: AVAssetWriterInput,
readerOutput: AVAssetReaderTrackOutput,
reader: AVAssetReader) {
while writerInput.isReadyForMoreMediaData {
guard isRunning, reader.status == .reading,
let sampleBuffer = readerOutput.copyNextSampleBuffer() else {
// 录制已停止或读取完毕
if isRunning {
writerInput.markAsFinished()
}
}
} 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
return
}
// 直接在后台队列处理,不走 MainActor(避免队列积压)
guard let firstTime = audioFirstFrameTime else {
// 视频第一帧还没到,跳过这个音频 buffer
// 重映射时间戳:源文件时间 → 相对于录制开始的时间
guard let firstTime = self.firstFrameTime else {
// 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()