[ZH][LINUX] Add FFmpegFile for AVIO abstraction (#714)

Author: feliwir

GeneralsMD/Code/GameEngineDevice/CMakeLists.txt

@@ -228,3 +228,19 @@ target_link_libraries(z_gameenginedevice PUBLIC
     milesstub
     z_gameengine
 )
+
+# FFmpeg
+find_package(FFMPEG)
+
+if(FFMPEG_FOUND)
+    target_sources(z_gameenginedevice PRIVATE
+        Include/VideoDevice/FFmpeg/FFmpegFile.h
+        #Include/VideoDevice/FFmpeg/FFmpegVideoPlayer.h
+        Source/VideoDevice/FFmpeg/FFmpegFile.cpp
+        #Source/VideoDevice/FFmpeg/FFmpegVideoPlayer.cpp
+    )
+
+    target_include_directories(z_gameenginedevice PRIVATE ${FFMPEG_INCLUDE_DIRS})
+    target_link_directories(z_gameenginedevice PRIVATE ${FFMPEG_LIBRARY_DIRS})
+    target_link_libraries(z_gameenginedevice PRIVATE ${FFMPEG_LIBRARIES})
+endif()

GeneralsMD/Code/GameEngineDevice/Include/VideoDevice/FFmpeg/FFmpegFile.h

@@ -0,0 +1,97 @@
+/*
+**	Command & Conquer Generals Zero Hour(tm)
+**	Copyright 2025 TheSuperHackers
+**
+**	This program is free software: you can redistribute it and/or modify
+**	it under the terms of the GNU General Public License as published by
+**	the Free Software Foundation, either version 3 of the License, or
+**	(at your option) any later version.
+**
+**	This program is distributed in the hope that it will be useful,
+**	but WITHOUT ANY WARRANTY; without even the implied warranty of
+**	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+**	GNU General Public License for more details.
+**
+**	You should have received a copy of the GNU General Public License
+**	along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+////////////////////////////////////////////////////////////////////////////////
+//																																						//
+//  (c) 2001-2003 Electronic Arts Inc.																				//
+//																																						//
+////////////////////////////////////////////////////////////////////////////////
+
+//////// FFmpegFile.h ///////////////////////////
+// Stephan Vedder, April 2025
+/////////////////////////////////////////////////
+
+#pragma once
+
+#include <Lib/BaseType.h>
+
+#include <functional>
+#include <vector>
+
+struct AVFormatContext;
+struct AVIOContext;
+struct AVCodec;
+struct AVCodecContext;
+struct AVFrame;
+struct AVPacket;
+struct File;
+
+using FFmpegFrameCallback = std::function<void(AVFrame *, int, int, void *)>;
+
+class FFmpegFile
+{
+public:
+	FFmpegFile();
+	// The constructur takes ownership of the file
+	explicit FFmpegFile(File *file);
+	~FFmpegFile();
+
+	Bool open(File *file);
+	void close();
+	void setFrameCallback(FFmpegFrameCallback callback) { m_frameCallback = callback; }
+	void setUserData(void *user_data) { m_userData = user_data; }
+	// Read & decode a packet from the container. Note that we could/should split this step
+	Bool decodePacket();
+	void seekFrame(int frame_idx);
+	Bool hasAudio() const;
+
+	// Audio specific
+	Int getSizeForSamples(Int numSamples) const;
+	Int getNumChannels() const;
+	Int getSampleRate() const;
+	Int getBytesPerSample() const;
+
+	// Video specific
+	Int getWidth() const;
+	Int getHeight() const;
+	Int getNumFrames() const;
+	Int getCurrentFrame() const;
+	Int getPixelFormat() const;
+	UnsignedInt getFrameTime() const;
+
+private:
+	struct FFmpegStream
+	{
+		AVCodecContext *codec_ctx = nullptr;
+		const AVCodec *codec = nullptr;
+		Int stream_idx = -1;
+		Int stream_type = -1;
+		AVFrame *frame = nullptr;
+	};
+
+	static Int readPacket(void *opaque, UnsignedByte *buf, Int buf_size);
+	const FFmpegStream *findMatch(int type) const;
+
+	FFmpegFrameCallback 		m_frameCallback = nullptr; ///< Callback for frame processing
+	AVFormatContext 			*m_fmtCtx = nullptr; ///< Format context for AVFormat
+	AVIOContext 				*m_avioCtx = nullptr; ///< IO context for AVFormat
+	AVPacket 					*m_packet = nullptr; ///< Current packet
+	std::vector<FFmpegStream> 	m_streams; ///< List of streams in the file
+	File 						*m_file = nullptr;	///< File handle for the file
+	void 						*m_userData = nullptr; ///< User data for the callback
+};