diff --git a/aegisub/subtitles_provider_libass.cpp b/aegisub/subtitles_provider_libass.cpp
new file mode 100644
index 000000000..f60e25040
--- /dev/null
+++ b/aegisub/subtitles_provider_libass.cpp
@@ -0,0 +1,179 @@
+// Copyright (c) 2006-2007, Rodrigo Braz Monteiro, Evgeniy Stepanov
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//   * Redistributions of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//   * Redistributions in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//   * Neither the name of the Aegisub Group nor the names of its contributors
+//     may be used to endorse or promote products derived from this software
+//     without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// -----------------------------------------------------------------------------
+//
+// AEGISUB
+//
+// Website: http://aegisub.cellosoft.com
+// Contact: mailto:zeratul@cellosoft.com
+//
+
+///////////
+// Headers
+#include "subtitles_provider.h"
+#include "ass_file.h"
+#include "video_context.h"
+#include "utils.h"
+extern "C" {
+#include <ass/ass.h>
+}
+
+
+///////////////////
+// libass provider
+class LibassSubtitlesProvider : public SubtitlesProvider {
+private:
+	static ass_library_t* ass_library;
+	ass_renderer_t* ass_renderer;
+	ass_track_t* ass_track;
+
+public:
+	LibassSubtitlesProvider();
+	~LibassSubtitlesProvider();
+
+	bool CanRaster() { return true; }
+
+	void LoadSubtitles(AssFile *subs);
+	void DrawSubtitles(AegiVideoFrame &dst,double time);
+};
+
+ass_library_t* LibassSubtitlesProvider::ass_library;
+
+
+///////////
+// Factory
+class LibassSubtitlesProviderFactory : public SubtitlesProviderFactory {
+public:
+	SubtitlesProvider *CreateProvider() { return new LibassSubtitlesProvider(); }
+	LibassSubtitlesProviderFactory() : SubtitlesProviderFactory(_T("libass")) {}
+} registerLibass;
+
+
+///////////////
+// Constructor
+LibassSubtitlesProvider::LibassSubtitlesProvider() {
+	// Initialize library
+	static bool first = true;
+	if (first) {
+		ass_library = ass_library_init();
+		if (!ass_library) throw _T("ass_library_init failed");
+
+		ass_set_fonts_dir(ass_library, "");
+		ass_set_extract_fonts(ass_library, 0);
+		ass_set_style_overrides(ass_library, NULL);
+		first = false;
+	}
+
+	// Initialize renderer
+	ass_track = NULL;
+	ass_renderer = ass_renderer_init(ass_library);
+	if (!ass_renderer) throw _T("ass_renderer_init failed");
+	ass_set_font_scale(ass_renderer, 1.);
+	ass_set_fonts(ass_renderer, NULL, "Sans");
+}
+
+
+//////////////
+// Destructor
+LibassSubtitlesProvider::~LibassSubtitlesProvider() {
+}
+
+
+//////////////////
+// Load subtitles
+void LibassSubtitlesProvider::LoadSubtitles(AssFile *subs) {
+	// Prepare subtitles
+	std::vector<char> data;
+	subs->SaveMemory(data,_T("UTF-8"));
+	delete subs;
+
+	// Load file
+	if (ass_track) ass_free_track(ass_track);
+	ass_track = ass_read_memory(ass_library, &data[3], data.size()-3,"UTF-8");	// Starting at 3 to avoid BOM
+	if (!ass_track) throw _T("libass failed to load subtitles.");
+}
+
+
+/////////////////////////////
+// Macros to get the colours
+#define _r(c)  ((c)>>24)
+#define _g(c)  (((c)>>16)&0xFF)
+#define _b(c)  (((c)>>8)&0xFF)
+#define _a(c)  ((c)&0xFF)
+
+//////////////////
+// Draw subtitles
+void LibassSubtitlesProvider::DrawSubtitles(AegiVideoFrame &frame,double time) {
+	// Set size
+	ass_set_frame_size(ass_renderer, frame.w, frame.h);
+
+	// Get frame
+	ass_image_t* img = ass_render_frame(ass_renderer, ass_track, int(time * 1000), NULL);
+
+	// libass actually returns several alpha-masked monochrome images.
+	// Here, we loop through their linked list, get the colour of the current, and blend into the frame.
+	// This is repeated for all of them.
+	while (img) {
+		// Get colours
+		unsigned int opacity = 255 - ((unsigned int)_a(img->color));
+		unsigned int r = (unsigned int)_r(img->color);
+		unsigned int g = (unsigned int)_g(img->color);
+		unsigned int b = (unsigned int) _b(img->color);
+
+		// Prepare copy
+		int src_stride = img->stride;
+		int dst_stride = frame.pitch[0];
+		int dst_delta = dst_stride - img->w*4;
+		//int stride = MIN(src_stride,dst_stride);
+		const unsigned char *src = img->bitmap;
+		unsigned char *dst = frame.data[0] + (img->dst_y * dst_stride + img->dst_x * 4);
+		unsigned int k,ck,t;
+
+		// Copy image to destination frame
+		for (int y=0;y<img->h;y++) {
+			//memcpy(dst,src,stride);
+			for (int x = 0; x < img->w; ++x) {
+				k = ((unsigned)src[x]) * opacity / 255;
+				ck = 255 - k;
+				t = *dst;
+				*dst++ = (k*b + ck*t) / 255;
+				t = *dst;
+				*dst++ = (k*g + ck*t) / 255;
+				t = *dst;
+				*dst++ = (k*r + ck*t) / 255;
+				dst++;
+			}
+
+			dst += dst_delta;
+			src += src_stride;
+		}
+
+		// Next image
+		img = img->next;
+	}
+}