Added frame-by-frame stepping hotkeys to media view on paused video.

Telegram/SourceFiles/media/streaming/media_streaming_common.h

@@ -61,6 +61,7 @@ struct VideoInformation {
 	QSize size;
 	QImage cover;
 	int rotation = 0;
+	float64 fps = 0.;
 	bool alpha = false;
 };
 

Telegram/SourceFiles/media/streaming/media_streaming_file.cpp

@@ -179,6 +179,10 @@ Stream File::Context::initStream(
 		result.rotation = FFmpeg::ReadRotationFromMetadata(info);
 		result.aspect = FFmpeg::ValidateAspectRatio(
 			info->sample_aspect_ratio);
+		const auto guessed = av_guess_frame_rate(format, info, nullptr);
+		if (guessed.num > 0 && guessed.den > 0) {
+			result.fps = av_q2d(guessed);
+		}
 	} else if (type == AVMEDIA_TYPE_AUDIO) {
 		result.frequency = info->codecpar->sample_rate;
 		if (!result.frequency) {

Telegram/SourceFiles/media/streaming/media_streaming_player.cpp

@@ -64,6 +64,7 @@ void SaveValidVideoInformation(
 	to.size = from.size;
 	to.cover = std::move(from.cover);
 	to.rotation = from.rotation;
+	to.fps = from.fps;
 	to.alpha = from.alpha;
 }
 

Telegram/SourceFiles/media/streaming/media_streaming_utility.h

@@ -41,6 +41,7 @@ struct Stream {
 	// Video only.
 	int rotation = 0;
 	AVRational aspect = FFmpeg::kNormalAspect;
+	float64 fps = 0.;
 	FFmpeg::SwscalePointer swscale;
 };
 

Telegram/SourceFiles/media/streaming/media_streaming_video_track.cpp

@@ -734,6 +734,7 @@ void VideoTrackObject::callReady() {
 			_stream.rotation),
 		.cover = frame->original,
 		.rotation = _stream.rotation,
+		.fps = _stream.fps,
 		.alpha = frame->alpha,
 	} });
 }

Telegram/SourceFiles/media/view/media_view_overlay_widget.cpp

@@ -146,6 +146,8 @@ constexpr auto kZoomToScreenLevel = 1024;
 constexpr auto kOverlayLoaderPriority = 2;
 constexpr auto kSeekTimeMs = 5 * crl::time(1000);
 constexpr auto kSeekTimeMsLong = 10 * crl::time(1000);
+constexpr auto kFrameStepFallbackFps = 30.;
+constexpr auto kFrameStepThrottleMs = crl::time(150);
 
 // macOS OpenGL renderer fails to render larger texture
 // even though it reports that max texture size is 16384.
@@ -617,6 +619,10 @@ OverlayWidget::OverlayWidget()
 		startSpeedBoost();
 	});
 
+	_frameStepThrottle.setCallback([=] {
+		flushPendingFrameStep();
+	});
+
 	_docRectImage = QImage(
 		st::mediaviewFileSize * style::DevicePixelRatio(),
 		QImage::Format_ARGB32_Premultiplied);
@@ -5071,6 +5077,21 @@ void OverlayWidget::playbackPauseResume() {
 	}
 }
 
+void OverlayWidget::flushPendingFrameStep() {
+	if (!_streamed || !_frameStepPending) {
+		_frameStepThrottle.cancel();
+		return;
+	}
+	const auto fps = _streamed->instance.info().video.fps;
+	const auto stepMs = 1000.
+		/ ((fps > 0.) ? fps : kFrameStepFallbackFps);
+	const auto shift = crl::time(std::round(_frameStepPending * stepMs));
+	_frameStepPending = 0;
+	_streamingStartPaused = true;
+	seekRelativeTime(shift);
+	_frameStepThrottle.callOnce(kFrameStepThrottleMs);
+}
+
 void OverlayWidget::seekRelativeTime(crl::time time) {
 	Expects(_streamed != nullptr);
 
@@ -6615,6 +6636,15 @@ void OverlayWidget::handleKeyPress(not_null<QKeyEvent*> e) {
 			activateControls();
 			seekRelativeTime(kSeekTimeMsLong);
 			return;
+		} else if ((key == Qt::Key_Period || key == Qt::Key_Comma)
+			&& _streamed->instance.player().paused()) {
+			activateControls();
+			_frameStepPending += (key == Qt::Key_Period) ? 1 : -1;
+			if (!_frameStepThrottle.isActive()) {
+				flushPendingFrameStep();
+				_frameStepThrottle.callOnce(kFrameStepThrottleMs);
+			}
+			return;
 		} else if (modifiers.testFlag(Qt::AltModifier)
 			&& (key == Qt::Key_Left || key == Qt::Key_Right)
 			&& _streamed->controls

Telegram/SourceFiles/media/view/media_view_overlay_widget.h

@@ -419,6 +419,7 @@ private:
 	void seekRelativeTime(crl::time time);
 	void restartAtProgress(float64 progress);
 	void restartAtSeekPosition(crl::time position);
+	void flushPendingFrameStep();
 
 	void refreshClipControllerGeometry();
 	void refreshCaptionGeometry();
@@ -805,6 +806,8 @@ private:
 	QRect _speedBoostRect;
 	Ui::Animations::Simple _speedBoostAnimation;
 	base::Timer _speedBoostHoldTimer;
+	base::Timer _frameStepThrottle;
+	int _frameStepPending = 0;
 	Ui::Animations::Basic _speedBoostTicker;
 	float64 _speedBoostPhase = 0.;
 	crl::time _speedBoostLastFrame = 0;