Add basic multimedia container and encoder interfaces

Adds the media subdirectory.

src/CMakeLists.txt

@@ -549,6 +549,7 @@ if(SRB2_CONFIG_ENABLE_TESTS)
 	add_subdirectory(tests)
 endif()
 add_subdirectory(menus)
+add_subdirectory(media)
 
 # strip debug symbols into separate file when using gcc.
 # to be consistent with Makefile, don't generate for OS X.

src/media/CMakeLists.txt

@@ -0,0 +1,7 @@
+target_sources(SRB2SDL2 PRIVATE
+	audio_encoder.hpp
+	container.hpp
+	encoder.hpp
+	video_encoder.hpp
+	video_frame.hpp
+)

src/media/audio_encoder.hpp

@@ -0,0 +1,39 @@
+// RING RACERS
+//-----------------------------------------------------------------------------
+// Copyright (C) 2023 by James Robert Roman
+//
+// This program is free software distributed under the
+// terms of the GNU General Public License, version 2.
+// See the 'LICENSE' file for more details.
+//-----------------------------------------------------------------------------
+
+#ifndef __SRB2_MEDIA_AUDIO_ENCODER_HPP__
+#define __SRB2_MEDIA_AUDIO_ENCODER_HPP__
+
+#include <tcb/span.hpp>
+
+#include "encoder.hpp"
+
+namespace srb2::media
+{
+
+class AudioEncoder : virtual public MediaEncoder
+{
+public:
+	using sample_buffer_t = tcb::span<const float>;
+
+	struct Config
+	{
+		int channels;
+		int sample_rate;
+	};
+
+	virtual void encode(sample_buffer_t samples) = 0;
+
+	virtual int channels() const = 0;
+	virtual int sample_rate() const = 0;
+};
+
+}; // namespace srb2::media
+
+#endif // __SRB2_MEDIA_AUDIO_ENCODER_HPP__

src/media/container.hpp

@@ -0,0 +1,53 @@
+// RING RACERS
+//-----------------------------------------------------------------------------
+// Copyright (C) 2023 by James Robert Roman
+//
+// This program is free software distributed under the
+// terms of the GNU General Public License, version 2.
+// See the 'LICENSE' file for more details.
+//-----------------------------------------------------------------------------
+
+#ifndef __SRB2_MEDIA_CONTAINER_HPP__
+#define __SRB2_MEDIA_CONTAINER_HPP__
+
+#include <chrono>
+#include <functional>
+#include <memory>
+#include <string>
+
+#include "audio_encoder.hpp"
+#include "video_encoder.hpp"
+
+namespace srb2::media
+{
+
+class MediaContainer
+{
+public:
+	using dtor_cb_t = std::function<void(const MediaContainer&)>;
+	using time_unit_t = std::chrono::duration<float>;
+
+	struct Config
+	{
+		std::string file_name;
+		dtor_cb_t destructor_callback;
+	};
+
+	virtual ~MediaContainer() = default;
+
+	virtual std::unique_ptr<AudioEncoder> make_audio_encoder(AudioEncoder::Config config) = 0;
+	virtual std::unique_ptr<VideoEncoder> make_video_encoder(VideoEncoder::Config config) = 0;
+
+	virtual const char* name() const = 0;
+	virtual const char* file_name() const = 0;
+
+	// These are normally estimates. However, when called from
+	// Config::destructor_callback, these are the exact final
+	// values.
+	virtual time_unit_t duration() const = 0;
+	virtual std::size_t size() const = 0;
+};
+
+}; // namespace srb2::media
+
+#endif // __SRB2_MEDIA_CONTAINER_HPP__

src/media/encoder.hpp

@@ -0,0 +1,51 @@
+// RING RACERS
+//-----------------------------------------------------------------------------
+// Copyright (C) 2023 by James Robert Roman
+//
+// This program is free software distributed under the
+// terms of the GNU General Public License, version 2.
+// See the 'LICENSE' file for more details.
+//-----------------------------------------------------------------------------
+
+#ifndef __SRB2_MEDIA_ENCODER_HPP__
+#define __SRB2_MEDIA_ENCODER_HPP__
+
+#include <chrono>
+#include <cstddef>
+
+#include <tcb/span.hpp>
+
+namespace srb2::media
+{
+
+class MediaEncoder
+{
+public:
+	using time_unit_t = std::chrono::duration<float>;
+
+	struct BitRate
+	{
+		std::size_t bits; // 8 bits = 1 byte :)
+		time_unit_t period;
+	};
+
+	virtual ~MediaEncoder() = default;
+
+	// Should be called finally but it's optional.
+	virtual void flush() = 0;
+
+	virtual const char* name() const = 0;
+
+	// Returns an average bit rate over a constant period of
+	// time, assuming no frames drops.
+	virtual BitRate estimated_bit_rate() const = 0;
+
+protected:
+	using frame_buffer_t = tcb::span<const std::byte>;
+
+	virtual void write_frame(frame_buffer_t frame, time_unit_t timestamp, bool is_key_frame) = 0;
+};
+
+}; // namespace srb2::media
+
+#endif // __SRB2_MEDIA_ENCODER_HPP__

src/media/video_encoder.hpp

@@ -0,0 +1,58 @@
+// RING RACERS
+//-----------------------------------------------------------------------------
+// Copyright (C) 2023 by James Robert Roman
+//
+// This program is free software distributed under the
+// terms of the GNU General Public License, version 2.
+// See the 'LICENSE' file for more details.
+//-----------------------------------------------------------------------------
+
+#ifndef __SRB2_MEDIA_VIDEO_ENCODER_HPP__
+#define __SRB2_MEDIA_VIDEO_ENCODER_HPP__
+
+#include "encoder.hpp"
+#include "video_frame.hpp"
+
+namespace srb2::media
+{
+
+class VideoEncoder : virtual public MediaEncoder
+{
+public:
+	struct Config
+	{
+		int width;
+		int height;
+		int frame_rate;
+		VideoFrame::BufferMethod buffer_method;
+	};
+
+	struct FrameCount
+	{
+		// Number of real frames, not counting frame skips.
+		int frames;
+
+		time_unit_t duration;
+	};
+
+	// VideoFrame::width() and VideoFrame::height() should be
+	// used on the returned frame.
+	virtual VideoFrame::instance_t new_frame(int width, int height, int pts) = 0;
+
+	virtual void encode(VideoFrame::instance_t frame) = 0;
+
+	virtual int width() const = 0;
+	virtual int height() const = 0;
+	virtual int frame_rate() const = 0;
+
+	// Reports the number of threads used, if the encoder is
+	// multithreaded.
+	virtual int thread_count() const = 0;
+
+	// Number of frames fully encoded so far.
+	virtual FrameCount frame_count() const = 0;
+};
+
+}; // namespace srb2::media
+
+#endif // __SRB2_MEDIA_VIDEO_ENCODER_HPP__

src/media/video_frame.hpp

@@ -0,0 +1,63 @@
+// RING RACERS
+//-----------------------------------------------------------------------------
+// Copyright (C) 2023 by James Robert Roman
+//
+// This program is free software distributed under the
+// terms of the GNU General Public License, version 2.
+// See the 'LICENSE' file for more details.
+//-----------------------------------------------------------------------------
+
+#ifndef __SRB2_MEDIA_VIDEO_FRAME_HPP__
+#define __SRB2_MEDIA_VIDEO_FRAME_HPP__
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+
+#include <tcb/span.hpp>
+
+namespace srb2::media
+{
+
+class VideoFrame
+{
+public:
+	using instance_t = std::unique_ptr<VideoFrame>;
+
+	enum class BufferMethod
+	{
+		// Returns an already allocated buffer for each
+		// frame. See VideoFrame::rgba_buffer(). The encoder
+		// completely manages allocating this buffer.
+		kEncoderAllocatedRGBA8888,
+	};
+
+	struct Buffer
+	{
+		tcb::span<uint8_t> plane;
+		std::size_t row_stride; // size of each row
+	};
+
+	virtual int width() const = 0;
+	virtual int height() const = 0;
+
+	int pts() const { return pts_; }
+
+	// Returns a buffer that should be
+	// filled with RGBA pixels.
+	//
+	// This method may only be used if
+	// the encoder was configured with
+	// BufferMethod::kEncoderAllocatedRGBA8888.
+	virtual const Buffer& rgba_buffer() const = 0;
+
+protected:
+	VideoFrame(int pts) : pts_(pts) {}
+
+private:
+	int pts_;
+};
+
+}; // namespace srb2::media
+
+#endif // __SRB2_MEDIA_VIDEO_FRAME_HPP__