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Implement positioned movie playback opcode

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gamer147
2026-07-29 15:41:01 -04:00
parent 92d7fb295e
commit cfd8809339
18 changed files with 523 additions and 46 deletions
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112
godot/FfmpegMovieDecoder.cs
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@@ -88,6 +88,7 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
private readonly Queue<MovieAudioChunk> _audioChunks = new();
private readonly AutoResetEvent _audioSpace = new(false);
private readonly int _maximumQueuedAudioFrames;
private readonly long _initialPositionMs;
private RgbaImage? _latestFrame;
private volatile bool _completed;
private volatile bool _videoTimelineCompleted;
@@ -101,6 +102,7 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
private long _firstFramePresentationTimeMs = -1;
public long? StopTimeMs => _source.Info.StopTimeMs;
public long InitialPositionMs => _initialPositionMs;
public bool IsCompleted => _completed;
public string? Failure => Volatile.Read(ref _failure);
public long? FirstFramePresentationTimeMs
@@ -114,12 +116,27 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
public MovieAudioInfo? AudioInfo { get; }
public bool AudioDecodingCompleted => _audioDecodingCompleted;
public FfmpegMovieDecoder(MoviePayload movie)
: this(new FfmpegMovieSession(movie), null) { }
public FfmpegMovieDecoder(MoviePayload movie, long initialPositionMs = 0)
: this(new FfmpegMovieSession(movie), null, initialPositionMs) { }
internal FfmpegMovieDecoder(IFfmpegFrameSource source, IMoviePacingClock? clock)
internal FfmpegMovieDecoder(IFfmpegFrameSource source, IMoviePacingClock? clock,
long initialPositionMs = 0)
{
_source = source ?? throw new ArgumentNullException(nameof(source));
_initialPositionMs = Math.Clamp(
initialPositionMs,
0,
Math.Max(0, source.Info.StopTimeMs - 1));
try
{
if (_initialPositionMs > 0)
source.Seek(_initialPositionMs);
}
catch
{
source.Dispose();
throw;
}
_clock = clock ?? (source.Info.HasAudio
? new ExternallyAdvancedMoviePacingClock()
: new StopwatchMoviePacingClock());
@@ -216,9 +233,24 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
long lastTimestamp = -1;
long decodedFrames = 0;
long firstTimestamp = -1;
FfmpegVideoFrame? selectedSeekFrame = null;
FfmpegVideoFrame? pendingAfterSeek = null;
if (_initialPositionMs > 0)
selectedSeekFrame = SelectFrameAtInitialPosition(out pendingAfterSeek);
while (!_cancel.WaitOne(0))
{
if (!_source.TryDecodeNextVideoFrame(out var frame))
FfmpegVideoFrame frame;
if (selectedSeekFrame != null)
{
frame = selectedSeekFrame;
selectedSeekFrame = null;
}
else if (pendingAfterSeek != null)
{
frame = pendingAfterSeek;
pendingAfterSeek = null;
}
else if (!_source.TryDecodeNextVideoFrame(out frame))
{
if (decodedFrames == 0)
throw new InvalidDataException("FFmpeg stream ended before producing a video frame");
@@ -265,11 +297,37 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
}
}
private FfmpegVideoFrame? SelectFrameAtInitialPosition(out FfmpegVideoFrame? pending)
{
pending = null;
FfmpegVideoFrame? candidate = null;
long priorTimestamp = -1;
while (!_cancel.WaitOne(0) && _source.TryDecodeNextVideoFrame(out FfmpegVideoFrame frame))
{
if (frame.PresentationTimeMs < 0 || frame.PresentationTimeMs < priorTimestamp)
throw new InvalidDataException(
$"FFmpeg returned non-monotonic video timestamp {frame.PresentationTimeMs} " +
$"after {priorTimestamp} during seek preroll");
priorTimestamp = frame.PresentationTimeMs;
if (frame.PresentationTimeMs <= _initialPositionMs)
{
candidate = frame;
continue;
}
if (candidate == null)
return frame;
pending = frame;
return candidate;
}
return candidate;
}
private void AudioDecodeThread()
{
try
{
long priorTimestamp = -1;
long priorSourceTimestamp = -1;
long priorRebasedTimestamp = -1;
while (!_cancel.WaitOne(0))
{
while (Volatile.Read(ref _queuedAudioFrames) >= _maximumQueuedAudioFrames)
@@ -286,18 +344,23 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
if (decoded.FrameCount <= 0
|| decoded.InterleavedStereo.Length != checked(decoded.FrameCount * 2)
|| decoded.PresentationTimeMs < 0
|| decoded.PresentationTimeMs < priorTimestamp)
|| decoded.PresentationTimeMs < priorSourceTimestamp)
throw new InvalidDataException(
$"FFmpeg returned invalid audio block {decoded.FrameCount}f " +
$"at {decoded.PresentationTimeMs} ms after {priorTimestamp} ms");
var chunk = new MovieAudioChunk(decoded.InterleavedStereo, decoded.FrameCount,
decoded.PresentationTimeMs);
$"at {decoded.PresentationTimeMs} ms after {priorSourceTimestamp} ms");
priorSourceTimestamp = decoded.PresentationTimeMs;
MovieAudioChunk? chunk = RebaseAudioChunk(decoded);
if (chunk == null) continue;
if (chunk.PresentationTimeMs < priorRebasedTimestamp)
throw new InvalidDataException(
$"FFmpeg seek produced non-monotonic rebased audio timestamp " +
$"{chunk.PresentationTimeMs} after {priorRebasedTimestamp} ms");
lock (_audioLock)
{
_audioChunks.Enqueue(chunk);
_queuedAudioFrames += chunk.FrameCount;
}
priorTimestamp = decoded.PresentationTimeMs;
priorRebasedTimestamp = chunk.PresentationTimeMs;
}
}
catch (Exception error)
@@ -310,6 +373,32 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
}
}
private MovieAudioChunk? RebaseAudioChunk(FfmpegAudioChunk decoded)
{
int trimFrames = 0;
if (_initialPositionMs > decoded.PresentationTimeMs)
{
long deltaMs = _initialPositionMs - decoded.PresentationTimeMs;
long required = checked(
(deltaMs * (long)_source.Info.AudioSampleRate + 999) / 1000);
trimFrames = checked((int)Math.Min(decoded.FrameCount, required));
}
if (trimFrames >= decoded.FrameCount) return null;
float[] samples = decoded.InterleavedStereo;
int frameCount = decoded.FrameCount - trimFrames;
if (trimFrames > 0)
{
var trimmed = new float[checked(frameCount * 2)];
Array.Copy(samples, checked(trimFrames * 2), trimmed, 0, trimmed.Length);
samples = trimmed;
}
long trimmedTimestamp = decoded.PresentationTimeMs
+ trimFrames * 1000L / _source.Info.AudioSampleRate;
long rebasedTimestamp = Math.Max(0, trimmedTimestamp - _initialPositionMs);
return new MovieAudioChunk(samples, frameCount, rebasedTimestamp);
}
private void Fail(Exception error)
{
Interlocked.CompareExchange(ref _failure, error.Message, null);
@@ -365,5 +454,6 @@ internal sealed class FfmpegMovieDecoder : IMovieDecoder
internal sealed class FfmpegMovieDecoderFactory : IMovieDecoderFactory
{
public IMovieDecoder Open(MoviePayload movie) => new FfmpegMovieDecoder(movie);
public IMovieDecoder Open(MoviePayload movie, long initialPositionMs = 0)
=> new FfmpegMovieDecoder(movie, initialPositionMs);
}