Implement Running Godot as Movie Writer

* Allows running the game in "movie writer" mode.
* It ensures entirely stable framerate, so your run can be saved stable and with proper sound (which is impossible if your CPU/GPU can't sustain doing this in real-time).
* If disabling vsync, it can save movies faster than the game is run, but if you want to control the interaction it can get difficult.
* Implements a simple, default MJPEG writer.

This new features has two main use cases, which have high demand:
* Saving game videos in high quality and ensuring the frame rate is *completely* stable, always.
* Using Godot as a tool to make movies and animations (which is ideal if you want interaction, or creating them procedurally. No other software is as good for this).

**Note**: This feature **IS NOT** for capturing real-time footage. Use something like OBS, SimpleScreenRecorder or FRAPS to achieve that, as they do a much better job at intercepting the compositor than Godot can probably do using Vulkan or OpenGL natively. If your game runs near real-time when capturing, you can still use this feature but it will play no sound (sound will be saved directly).

Usage:

$ godot --write-movie movie.avi [scene_file.tscn]

Missing:

* Options for configuring video writing via GLOBAL_DEF
* UI Menu for launching with this mode from the editor.
* Add to list of command line options.
* Add a feature tag to override configurations when movie writing (fantastic for saving videos with highest quality settings).

7 files changed, 33 insertions, 1 deletions

diff --git a/core/config/project_settings.cpp b/core/config/project_settings.cpp
index 12d936d456..570dc675a8 100644
--- a/core/config/project_settings.cpp
+++ b/core/config/project_settings.cpp
@@ -41,7 +41,6 @@
 #include "core/os/keyboard.h"
 #include "core/variant/variant_parser.h"
 #include "core/version.h"
-
 #include "modules/modules_enabled.gen.h" // For mono.
 
 const String ProjectSettings::PROJECT_DATA_DIR_NAME_SUFFIX = "godot";
diff --git a/core/core_constants.cpp b/core/core_constants.cpp
index 4f22c99656..3373f4f1e5 100644
--- a/core/core_constants.cpp
+++ b/core/core_constants.cpp
@@ -588,6 +588,7 @@ void register_global_constants() {
 	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_OBJECT_TOO_BIG);
 	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_NODE_PATH_VALID_TYPES);
 	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_SAVE_FILE);
+	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_GLOBAL_SAVE_FILE);
 	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_INT_IS_OBJECTID);
 	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_INT_IS_POINTER);
 	BIND_CORE_ENUM_CONSTANT(PROPERTY_HINT_ARRAY_TYPE);
diff --git a/core/io/image.cpp b/core/io/image.cpp
index dfba45c4e9..6585fd9adf 100644
--- a/core/io/image.cpp
+++ b/core/io/image.cpp
@@ -81,9 +81,11 @@ const char *Image::format_names[Image::FORMAT_MAX] = {
 };
 
 SavePNGFunc Image::save_png_func = nullptr;
+SaveJPGFunc Image::save_jpg_func = nullptr;
 SaveEXRFunc Image::save_exr_func = nullptr;
 
 SavePNGBufferFunc Image::save_png_buffer_func = nullptr;
+SaveJPGBufferFunc Image::save_jpg_buffer_func = nullptr;
 
 void Image::_put_pixelb(int p_x, int p_y, uint32_t p_pixel_size, uint8_t *p_data, const uint8_t *p_pixel) {
 	uint32_t ofs = (p_y * width + p_x) * p_pixel_size;
@@ -2286,6 +2288,14 @@ Error Image::save_png(const String &p_path) const {
 	return save_png_func(p_path, Ref<Image>((Image *)this));
 }
 
+Error Image::save_jpg(const String &p_path, float p_quality) const {
+	if (save_jpg_func == nullptr) {
+		return ERR_UNAVAILABLE;
+	}
+
+	return save_jpg_func(p_path, Ref<Image>((Image *)this), p_quality);
+}
+
 Vector<uint8_t> Image::save_png_to_buffer() const {
 	if (save_png_buffer_func == nullptr) {
 		return Vector<uint8_t>();
@@ -2294,6 +2304,14 @@ Vector<uint8_t> Image::save_png_to_buffer() const {
 	return save_png_buffer_func(Ref<Image>((Image *)this));
 }
 
+Vector<uint8_t> Image::save_jpg_to_buffer(float p_quality) const {
+	if (save_jpg_buffer_func == nullptr) {
+		return Vector<uint8_t>();
+	}
+
+	return save_jpg_buffer_func(Ref<Image>((Image *)this), p_quality);
+}
+
 Error Image::save_exr(const String &p_path, bool p_grayscale) const {
 	if (save_exr_func == nullptr) {
 		return ERR_UNAVAILABLE;
@@ -3138,6 +3156,8 @@ void Image::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("load", "path"), &Image::load);
 	ClassDB::bind_method(D_METHOD("save_png", "path"), &Image::save_png);
 	ClassDB::bind_method(D_METHOD("save_png_to_buffer"), &Image::save_png_to_buffer);
+	ClassDB::bind_method(D_METHOD("save_jpg", "path", "quality"), &Image::save_jpg, DEFVAL(0.75));
+	ClassDB::bind_method(D_METHOD("save_jpg_to_buffer", "quality"), &Image::save_jpg_to_buffer, DEFVAL(0.75));
 	ClassDB::bind_method(D_METHOD("save_exr", "path", "grayscale"), &Image::save_exr, DEFVAL(false));
 
 	ClassDB::bind_method(D_METHOD("detect_alpha"), &Image::detect_alpha);
diff --git a/core/io/image.h b/core/io/image.h
index 1025554d51..88b80dc984 100644
--- a/core/io/image.h
+++ b/core/io/image.h
@@ -45,6 +45,8 @@ class Image;
 
 typedef Error (*SavePNGFunc)(const String &p_path, const Ref<Image> &p_img);
 typedef Vector<uint8_t> (*SavePNGBufferFunc)(const Ref<Image> &p_img);
+typedef Error (*SaveJPGFunc)(const String &p_path, const Ref<Image> &p_img, float p_quality);
+typedef Vector<uint8_t> (*SaveJPGBufferFunc)(const Ref<Image> &p_img, float p_quality);
 typedef Ref<Image> (*ImageMemLoadFunc)(const uint8_t *p_png, int p_size);
 
 typedef Error (*SaveEXRFunc)(const String &p_path, const Ref<Image> &p_img, bool p_grayscale);
@@ -54,8 +56,10 @@ class Image : public Resource {
 
 public:
 	static SavePNGFunc save_png_func;
+	static SaveJPGFunc save_jpg_func;
 	static SaveEXRFunc save_exr_func;
 	static SavePNGBufferFunc save_png_buffer_func;
+	static SaveJPGBufferFunc save_jpg_buffer_func;
 
 	enum {
 		MAX_WIDTH = (1 << 24), // force a limit somehow
@@ -281,7 +285,9 @@ public:
 
 	Error load(const String &p_path);
 	Error save_png(const String &p_path) const;
+	Error save_jpg(const String &p_path, float p_quality = 0.75) const;
 	Vector<uint8_t> save_png_to_buffer() const;
+	Vector<uint8_t> save_jpg_to_buffer(float p_quality = 0.75) const;
 	Error save_exr(const String &p_path, bool p_grayscale) const;
 
 	void create_empty(int p_width, int p_height, bool p_use_mipmaps, Format p_format) {
diff --git a/core/object/object.h b/core/object/object.h
index 7cbedd29d9..d0c6c0cb01 100644
--- a/core/object/object.h
+++ b/core/object/object.h
@@ -85,6 +85,7 @@ enum PropertyHint {
 	PROPERTY_HINT_OBJECT_TOO_BIG, ///< object is too big to send
 	PROPERTY_HINT_NODE_PATH_VALID_TYPES,
 	PROPERTY_HINT_SAVE_FILE, ///< a file path must be passed, hint_text (optionally) is a filter "*.png,*.wav,*.doc,". This opens a save dialog
+	PROPERTY_HINT_GLOBAL_SAVE_FILE, ///< a file path must be passed, hint_text (optionally) is a filter "*.png,*.wav,*.doc,". This opens a save dialog
 	PROPERTY_HINT_INT_IS_OBJECTID,
 	PROPERTY_HINT_ARRAY_TYPE,
 	PROPERTY_HINT_INT_IS_POINTER,
diff --git a/core/os/os.cpp b/core/os/os.cpp
index 327f1c95f2..93477f4288 100644
--- a/core/os/os.cpp
+++ b/core/os/os.cpp
@@ -388,6 +388,10 @@ bool OS::has_feature(const String &p_feature) {
 		return true;
 	}
 
+	if (p_feature == "movie") {
+		return _writing_movie;
+	}
+
 #ifdef DEBUG_ENABLED
 	if (p_feature == "debug") {
 		return true;
diff --git a/core/os/os.h b/core/os/os.h
index 157b8ab992..c6ea9d869a 100644
--- a/core/os/os.h
+++ b/core/os/os.h
@@ -58,6 +58,7 @@ class OS {
 	bool _allow_layered = false;
 	bool _stdout_enabled = true;
 	bool _stderr_enabled = true;
+	bool _writing_movie = false;
 
 	CompositeLogger *_logger = nullptr;