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).

2 files changed, 56 insertions, 1 deletions

diff --git a/modules/jpg/SCsub b/modules/jpg/SCsub
index 7c6ceeea29..b840542c1b 100644
--- a/modules/jpg/SCsub
+++ b/modules/jpg/SCsub
@@ -13,6 +13,7 @@ thirdparty_obj = []
 thirdparty_dir = "#thirdparty/jpeg-compressor/"
 thirdparty_sources = [
     "jpgd.cpp",
+    "jpge.cpp",
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
diff --git a/modules/jpg/image_loader_jpegd.cpp b/modules/jpg/image_loader_jpegd.cpp
index 51358876a4..0e03fa65c8 100644
--- a/modules/jpg/image_loader_jpegd.cpp
+++ b/modules/jpg/image_loader_jpegd.cpp
@@ -33,7 +33,8 @@
 #include "core/os/os.h"
 #include "core/string/print_string.h"
 
-#include <jpgd.h>
+#include "thirdparty/jpeg-compressor/jpgd.h"
+#include "thirdparty/jpeg-compressor/jpge.h"
 #include <string.h>
 
 Error jpeg_load_image_from_buffer(Image *p_image, const uint8_t *p_buffer, int p_buffer_len) {
@@ -131,6 +132,59 @@ static Ref<Image> _jpegd_mem_loader_func(const uint8_t *p_png, int p_size) {
 	return img;
 }
 
+static Error _jpgd_save_func(const String &p_path, const Ref<Image> &p_img, float p_quality) {
+	return OK;
+}
+
+class ImageLoaderJPGOSFile : public jpge::output_stream {
+public:
+	Ref<FileAccess> f;
+
+	virtual bool put_buf(const void *Pbuf, int len) {
+		f->store_buffer((const uint8_t *)Pbuf, len);
+		return true;
+	}
+};
+
+class ImageLoaderJPGOSBuffer : public jpge::output_stream {
+public:
+	Vector<uint8_t> *buffer = nullptr;
+	virtual bool put_buf(const void *Pbuf, int len) {
+		uint32_t base = buffer->size();
+		buffer->resize(base + len);
+		memcpy(buffer->ptrw() + base, Pbuf, len);
+		return true;
+	}
+};
+
+static Vector<uint8_t> _jpgd_buffer_save_func(const Ref<Image> &p_img, float p_quality) {
+	ERR_FAIL_COND_V(p_img.is_null() || p_img->is_empty(), Vector<uint8_t>());
+	Ref<Image> image = p_img;
+	if (image->get_format() != Image::FORMAT_RGB8) {
+		image->convert(Image::FORMAT_ETC2_RGB8);
+	}
+
+	jpge::params p;
+	p.m_quality = CLAMP(p_quality * 100, 1, 100);
+	Vector<uint8_t> output;
+	ImageLoaderJPGOSBuffer ob;
+	ob.buffer = &output;
+
+	jpge::jpeg_encoder enc;
+	enc.init(&ob, image->get_width(), image->get_height(), 3, p);
+
+	const uint8_t *src_data = image->get_data().ptr();
+	for (int i = 0; i < image->get_height(); i++) {
+		enc.process_scanline(&src_data[i * image->get_width() * 3]);
+	}
+
+	enc.process_scanline(nullptr);
+
+	return output;
+}
+
 ImageLoaderJPG::ImageLoaderJPG() {
 	Image::_jpg_mem_loader_func = _jpegd_mem_loader_func;
+	Image::save_jpg_func = _jpgd_save_func;
+	Image::save_jpg_buffer_func = _jpgd_buffer_save_func;
 }