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Validate integrated FFmpeg video hardening stack #146

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157 changes: 135 additions & 22 deletions src/ui/Logic/VideoPlayers/Ffmpeg/FfmpegPlayer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -304,6 +304,45 @@ public double Position
return duration > 0 ? Math.Min(value, duration) : value;
}

/// <summary>
/// State visible after a native seek failure. Only the request that actually failed may roll
/// back to the committed pipeline serial/position; a newer request that arrived while
/// av_seek_frame was blocked must remain pending.
/// </summary>
internal static (int RequestedSerial, double RequestedTarget) FailedSeekState(
int failedSerial,
int currentSerial,
int requestedSerial,
double requestedTarget,
double currentPosition)
{
return requestedSerial == failedSerial
? (currentSerial, currentPosition)
: (requestedSerial, requestedTarget);
}

internal static bool ShouldAutoRewindOnPlay(
bool hasOutstandingSeek,
bool endReached,
double duration,
double position)
{
return !hasOutstandingSeek &&
(endReached || (duration > 0 && position >= duration - 0.01));
}

internal static bool ShouldReachAudioOnlyEnd(
bool playing,
bool hasOutstandingSeek,
double duration,
double position)
{
return playing &&
!hasOutstandingSeek &&
duration > 0 &&
position >= duration;
}

public double Duration => _session?.Duration ?? 0;

public int VolumeMaximum => 100;
Expand Down Expand Up @@ -359,7 +398,7 @@ public void Dispose()
CloseFile();
}

private void Present(VideoFrame frame, VideoFrameQueue pool)
private void PublishFrame(VideoFrame frame, VideoFrameQueue pool)
{
VideoFrame? previous;
lock (_currentFrameLock)
Expand All @@ -370,6 +409,10 @@ private void Present(VideoFrame frame, VideoFrameQueue pool)

pool.Return(previous);
Interlocked.Increment(ref _frameVersion);
}

private void NotifyFrameReady()
{
FrameReady?.Invoke();
}

Expand Down Expand Up @@ -405,6 +448,11 @@ or AVSampleFormat.AV_SAMPLE_FMT_DBLP
or AVSampleFormat.AV_SAMPLE_FMT_S64P;
}

internal static bool CanPublishVideoFrame(int frameSerial, int currentSerial)
{
return frameSerial == currentSerial;
}

/// <summary>
/// avcodec_send_packet(EAGAIN) means the decoder rejected the input. The same packet may be
/// resent only after receive_frame made progress, and only while the serial is still current.
Expand Down Expand Up @@ -679,12 +727,12 @@ public void Play()
return;
}

if (_endReached || (Duration > 0 && Position >= Duration - 0.01))
var hasOutstandingSeek = HasOutstandingSeek();
if (ShouldAutoRewindOnPlay(hasOutstandingSeek, _endReached, Duration, Position))
{
Seek(0);
}

_endReached = false;
_playing = true;
_wallClockBase = _pausedPosition;
_wallClock.Restart();
Expand Down Expand Up @@ -736,10 +784,11 @@ public void Seek(double seconds)
_requestedSerial++;
_requestedTarget = seconds;
_seekPending = true;
_pausedPosition = seconds;
}

_endReached = false;
// Keep the committed playhead/end state unchanged until libavformat accepts the seek.
// Position reports _requestedTarget while the request is outstanding, so optimistic
// mutation here is unnecessary and would corrupt state if av_seek_frame fails.
_demuxWake.Set();
}

Expand Down Expand Up @@ -799,6 +848,14 @@ private double Clock()
return _wallClockBase + _wallClock.Elapsed.TotalSeconds * _speed;
}

private bool HasOutstandingSeek()
{
lock (_seekLock)
{
return _requestedSerial != _currentSerial;
}
}

/// <summary>True when a seek newer than the given serial has been requested (performed or not).</summary>
private bool SeekRequestedSince(int serial)
{
Expand All @@ -819,8 +876,11 @@ private void DemuxLoop()
{
if (TryTakeSeek(out var target, out var serial))
{
PerformSeek(target, serial);
eof = false;
if (PerformSeek(target, serial))
{
eof = false;
}

continue;
}

Expand Down Expand Up @@ -894,13 +954,15 @@ private bool TryTakeSeek(out double target, out int serial)
}
}

private void PerformSeek(double target, int serial)
private bool PerformSeek(double target, int serial)
{
var timestamp = (long)((target + _startTimeSeconds) * ffmpeg.AV_TIME_BASE);
var result = ffmpeg.av_seek_frame(_format, -1, timestamp, ffmpeg.AVSEEK_FLAG_BACKWARD);
if (result < 0)
{
System.Diagnostics.Debug.WriteLine($"ffmpeg seek failed: {FfmpegLibraries.ErrorText(result)}");
Se.LogError($"ffmpeg player: seek to {target:0.###} s failed ({FfmpegLibraries.ErrorText(result)})");
RollBackFailedSeek(serial);
return false;
}

lock (_seekLock)
Expand All @@ -920,11 +982,35 @@ private void PerformSeek(double target, int serial)
}
}

_endReached = false;
_videoPackets.Flush(serial, target);
_audioPackets.Flush(serial, target);
_videoFrames.Flush();
_audioSink.Reset();
_presentWake.Set();
return true;
}

private void RollBackFailedSeek(int serial)
{
// Seek no longer mutates the committed paused position, so this remains the actual
// position when paused. While playing, Clock() follows the still-current pipeline.
var currentPosition = _playing ? Clock() : _pausedPosition;

lock (_seekLock)
{
var state = FailedSeekState(
serial,
_currentSerial,
_requestedSerial,
_requestedTarget,
currentPosition);

_requestedSerial = state.RequestedSerial;
_requestedTarget = state.RequestedTarget;
}

_presentWake.Set();
}

// ---------------------------------------------------------------- video decode
Expand All @@ -940,6 +1026,7 @@ private void VideoLoop()
var swsSourceFormat = AVPixelFormat.AV_PIX_FMT_NONE;
var outputWidth = 0;
var outputHeight = 0;
VideoFrame? lastDropped = null; // detached from the queue while seeking; return it on every exit

try
{
Expand All @@ -959,7 +1046,6 @@ private void VideoLoop()
var minimumReplaySerial = -1;
var dropUntil = -1.0;
var presentedForSerial = false;
VideoFrame? lastDropped = null; // kept so a target past the last picture still shows something

while (!_closing)
{
Expand Down Expand Up @@ -1171,6 +1257,8 @@ private void VideoLoop()
}
finally
{
_videoFrames.Return(lastDropped);

if (sws != null)
{
ffmpeg.sws_freeContext(sws);
Expand Down Expand Up @@ -1758,6 +1846,15 @@ private void PresentLoop()
continue;
}

if (SeekRequestedSince(frame.Serial))
{
// Keep the old EOS marker until the seek commits or fails. Without
// this guard a video-only stream can ReachEnd while av_seek_frame is
// still blocked and lose a Play issued for the requested destination.
_presentWake.WaitOne(20);
continue;
}

if (_hasAudio)
{
// Video ended first; let the audio play out before stopping. The wake
Expand Down Expand Up @@ -1868,7 +1965,7 @@ private void PresentLoop()

private void PresentAudioOnlyTick()
{
if (_playing && Duration > 0 && Clock() >= Duration)
if (ShouldReachAudioOnlyEnd(_playing, HasOutstandingSeek(), Duration, Clock()))
{
ReachEnd();
}
Expand All @@ -1885,15 +1982,25 @@ private void ReachEnd()

private void ShowFrame(VideoFrame frame)
{
var popped = _videoFrames.Pop();
if (!ReferenceEquals(popped, frame))
{
_videoFrames.Return(popped);
return;
}

var published = false;
lock (_seekLock)
{
// The initial PresentLoop check is only advisory: a successful seek can advance
// _currentSerial before this frame is popped. Claim and publish the frame while
// holding the same lock that commits seek serials, so an old serial can never be
// published after a newer seek has committed.
if (!CanPublishVideoFrame(frame.Serial, _currentSerial))
{
return;
}

var popped = _videoFrames.Pop();
if (!ReferenceEquals(popped, frame))
{
_videoFrames.Return(popped);
return;
}

if (frame.Serial > _restartSerial)
{
_restartSerial = frame.Serial;
Expand All @@ -1906,12 +2013,18 @@ private void ShowFrame(VideoFrame frame)
{
_pausedPosition = frame.Pts;
}

// Publish frame state before releasing the seek lock. The callback itself is
// deliberately deferred until after the lock so UI/user code never runs under it.
Interlocked.Exchange(ref _lastRestartTimestamp, Stopwatch.GetTimestamp());
_owner.PublishFrame(frame, _videoFrames);
published = true;
}

// Timestamp after the serial so HasPlaybackRestartedSince never sees a new
// timestamp with an old serial.
Interlocked.Exchange(ref _lastRestartTimestamp, Stopwatch.GetTimestamp());
_owner.Present(frame, _videoFrames);
if (published)
{
_owner.NotifyFrameReady();
}
}

// ---------------------------------------------------------------- teardown
Expand Down
17 changes: 7 additions & 10 deletions src/ui/Logic/VideoPlayers/Ffmpeg/VideoFrameQueue.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -156,22 +156,19 @@ public void Return(VideoFrame? frame)
}
}

/// <summary>Drops all queued frames (back to the pool).</summary>
/// <summary>
/// Drops all queued frames after a seek. Queued frames are disposed rather than returned to
/// the pool: the presenter may still hold a reference obtained from Peek/PeekSecond before
/// this flush. Reusing such an object immediately would let the decoder overwrite its serial,
/// timestamp and pixel buffer while the presenter is still reading the stale reference.
/// </summary>
public void Flush()
{
lock (_lock)
{
while (_frames.Count > 0)
{
var frame = _frames.Dequeue();
if (frame.Data != System.IntPtr.Zero && frame.Width == _width && frame.Height == _height)
{
_pool.Push(frame);
}
else
{
frame.Dispose();
}
_frames.Dequeue().Dispose();
}

Monitor.PulseAll(_lock);
Expand Down
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