Implement precise seek in streaming.

Telegram/SourceFiles/data/data_document.cpp

@@ -302,6 +302,7 @@ void StartStreaming(
 		static auto options = Media::Streaming::PlaybackOptions();
 		static auto speed = 1.;
 		static auto step = pow(2., 1. / 12);
+		static auto frame = QImage();
 
 		class Panel
 #if defined Q_OS_MAC && !defined OS_MAC_OLD
@@ -339,6 +340,9 @@ void StartStreaming(
 				player->pause();
 			}
 			void mouseReleaseEvent(QMouseEvent *e) override {
+				if (player->ready()) {
+					frame = player->frame({});
+				}
 				preloaded = position = options.position = std::clamp(
 					(duration * e->pos().x()) / width(),
 					crl::time(0),
@@ -364,6 +368,7 @@ void StartStreaming(
 		options.speed = speed;
 		//options.syncVideoByAudio = false;
 		preloaded = position = options.position = 0;
+		frame = QImage();
 		player->play(options);
 		player->updates(
 		) | rpl::start_with_next_error_done([=](Update &&update) {
@@ -391,7 +396,11 @@ void StartStreaming(
 						if (player->ready()) {
 							Painter(video.get()).drawImage(
 								video->rect(),
-								player->frame(FrameRequest()));
+								player->frame({}));
+						} else if (!frame.isNull()) {
+							Painter(video.get()).drawImage(
+								video->rect(),
+								frame);
 						} else {
 							Painter(video.get()).fillRect(
 								rect,

Telegram/SourceFiles/media/streaming/media_streaming_audio_track.cpp

@@ -61,29 +61,51 @@ bool AudioTrack::initialized() const {
 }
 
 bool AudioTrack::tryReadFirstFrame(Packet &&packet) {
-	// #TODO streaming fix seek to the end.
 	if (ProcessPacket(_stream, std::move(packet)).failed()) {
 		return false;
 	}
 	if (const auto error = ReadNextFrame(_stream)) {
 		if (error.code() == AVERROR_EOF) {
-			// #TODO streaming fix seek to the end.
-			return false;
+			if (!_initialSkippingFrame) {
+				return false;
+			}
+			// Return the last valid frame if we seek too far.
+			_stream.frame = std::move(_initialSkippingFrame);
+			return processFirstFrame();
 		} else if (error.code() != AVERROR(EAGAIN) || _noMoreData) {
 			return false;
+		} else {
+			// Waiting for more packets.
+			return true;
 		}
-		return true;
 	} else if (!fillStateFromFrame()) {
 		return false;
+	} else if (_startedPosition < _options.position) {
+		// Seek was with AVSEEK_FLAG_BACKWARD so first we get old frames.
+		// Try skipping frames until one is after the requested position.
+		std::swap(_initialSkippingFrame, _stream.frame);
+		if (!_stream.frame) {
+			_stream.frame = MakeFramePointer();
+		}
+		return true;
+	} else {
+		return processFirstFrame();
 	}
+}
+
+bool AudioTrack::processFirstFrame() {
 	mixerInit();
 	callReady();
 	return true;
 }
 
 bool AudioTrack::fillStateFromFrame() {
-	_startedPosition = FramePosition(_stream);
-	return (_startedPosition != kTimeUnknown);
+	const auto position = FramePosition(_stream);
+	if (position == kTimeUnknown) {
+		return false;
+	}
+	_startedPosition = position;
+	return true;
 }
 
 void AudioTrack::mixerInit() {

Telegram/SourceFiles/media/streaming/media_streaming_audio_track.h

@@ -52,6 +52,7 @@ private:
 	[[nodiscard]] bool initialized() const;
 	[[nodiscard]] bool tryReadFirstFrame(Packet &&packet);
 	[[nodiscard]] bool fillStateFromFrame();
+	[[nodiscard]] bool processFirstFrame();
 	void mixerInit();
 	void mixerEnqueue(Packet &&packet);
 	void mixerForceToBuffer();
@@ -78,6 +79,9 @@ private:
 	// After that accessed from the main thread.
 	rpl::variable<crl::time> _playPosition;
 
+	// For initial frame skipping for an exact seek.
+	FramePointer _initialSkippingFrame;
+
 };
 
 } // namespace Streaming

Telegram/SourceFiles/media/streaming/media_streaming_file.cpp

@@ -110,15 +110,8 @@ Stream File::Context::initStream(AVMediaType type) {
 	}
 
 	const auto info = _formatContext->streams[index];
-	result.codec = MakeCodecPointer(info);
-	if (!result.codec) {
-		return {};
-	}
-
 	if (type == AVMEDIA_TYPE_VIDEO) {
-		const auto codec = result.codec.get();
 		result.rotation = ReadRotationFromMetadata(info);
-		result.dimensions = QSize(codec->width, codec->height);
 	} else if (type == AVMEDIA_TYPE_AUDIO) {
 		result.frequency = info->codecpar->sample_rate;
 		if (!result.frequency) {
@@ -126,6 +119,11 @@ Stream File::Context::initStream(AVMediaType type) {
 		}
 	}
 
+	result.codec = MakeCodecPointer(info);
+	if (!result.codec) {
+		return {};
+	}
+
 	result.frame = MakeFramePointer();
 	if (!result.frame) {
 		return {};

Telegram/SourceFiles/media/streaming/media_streaming_utility.h

@@ -154,7 +154,6 @@ struct Stream {
 
 	// Video only.
 	int rotation = 0;
-	QSize dimensions;
 	SwsContextPointer swsContext;
 };
 

Telegram/SourceFiles/media/streaming/media_streaming_video_track.cpp

@@ -47,10 +47,7 @@ private:
 	[[nodiscard]] bool interrupted() const;
 	[[nodiscard]] bool tryReadFirstFrame(Packet &&packet);
 	[[nodiscard]] bool fillStateFromFrame();
-	[[nodiscard]] bool fillStateFromFakeLastFrame();
-	[[nodiscard]] bool fillStateFromFrameTime(crl::time frameTime);
-	[[nodiscard]] QImage createFakeLastFrame() const;
-	[[nodiscard]] bool processFirstFrame(QImage frame);
+	[[nodiscard]] bool processFirstFrame();
 	void queueReadFrames(crl::time delay = 0);
 	void readFrames();
 	[[nodiscard]] bool readFrame(not_null<Frame*> frame);
@@ -83,6 +80,9 @@ private:
 	bool _queued = false;
 	base::ConcurrentTimer _readFramesTimer;
 
+	// For initial frame skipping for an exact seek.
+	FramePointer _initialSkippingFrame;
+
 };
 
 VideoTrackObject::VideoTrackObject(
@@ -259,10 +259,12 @@ bool VideoTrackObject::tryReadFirstFrame(Packet &&packet) {
 	auto frame = QImage();
 	if (const auto error = ReadNextFrame(_stream)) {
 		if (error.code() == AVERROR_EOF) {
-			if (!fillStateFromFakeLastFrame()) {
+			if (!_initialSkippingFrame) {
 				return false;
 			}
-			return processFirstFrame(createFakeLastFrame());
+			// Return the last valid frame if we seek too far.
+			_stream.frame = std::move(_initialSkippingFrame);
+			return processFirstFrame();
 		} else if (error.code() != AVERROR(EAGAIN) || _noMoreData) {
 			return false;
 		} else {
@@ -271,22 +273,21 @@ bool VideoTrackObject::tryReadFirstFrame(Packet &&packet) {
 		}
 	} else if (!fillStateFromFrame()) {
 		return false;
+	} else if (_syncTimePoint.trackTime < _options.position) {
+		// Seek was with AVSEEK_FLAG_BACKWARD so first we get old frames.
+		// Try skipping frames until one is after the requested position.
+		std::swap(_initialSkippingFrame, _stream.frame);
+		if (!_stream.frame) {
+			_stream.frame = MakeFramePointer();
+		}
+		return true;
+	} else {
+		return processFirstFrame();
 	}
-	return processFirstFrame(ConvertFrame(_stream, QSize(), QImage()));
 }
 
-QImage VideoTrackObject::createFakeLastFrame() const {
-	if (_stream.dimensions.isEmpty()) {
-		LOG(("Streaming Error: Can't seek to the end of the video "
-			"in case the codec doesn't provide valid dimensions."));
-		return QImage();
-	}
-	auto result = CreateImageForOriginalFrame(_stream.dimensions);
-	result.fill(Qt::black);
-	return result;
-}
-
-bool VideoTrackObject::processFirstFrame(QImage frame) {
+bool VideoTrackObject::processFirstFrame() {
+	auto frame = ConvertFrame(_stream, QSize(), QImage());
 	if (frame.isNull()) {
 		return false;
 	}
@@ -312,20 +313,11 @@ crl::time VideoTrackObject::currentFramePosition() const {
 }
 
 bool VideoTrackObject::fillStateFromFrame() {
-	return fillStateFromFrameTime(currentFramePosition());
-}
-
-bool VideoTrackObject::fillStateFromFakeLastFrame() {
-	return fillStateFromFrameTime(_stream.duration);
-}
-
-bool VideoTrackObject::fillStateFromFrameTime(crl::time frameTime) {
-	Expects(_syncTimePoint.trackTime == kTimeUnknown);
-
-	if (frameTime == kTimeUnknown) {
+	const auto position = currentFramePosition();
+	if (position == kTimeUnknown) {
 		return false;
 	}
-	_syncTimePoint.trackTime = frameTime;
+	_syncTimePoint.trackTime = position;
 	return true;
 }