Fix GL information fetching.
[dcpomatic.git] / src / wx / gl_video_view.cc
1 /*
2     Copyright (C) 2018-2021 Carl Hetherington <cth@carlh.net>
3
4     This file is part of DCP-o-matic.
5
6     DCP-o-matic is free software; you can redistribute it and/or modify
7     it under the terms of the GNU General Public License as published by
8     the Free Software Foundation; either version 2 of the License, or
9     (at your option) any later version.
10
11     DCP-o-matic is distributed in the hope that it will be useful,
12     but WITHOUT ANY WARRANTY; without even the implied warranty of
13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14     GNU General Public License for more details.
15
16     You should have received a copy of the GNU General Public License
17     along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
18
19 */
20
21
22 #ifdef DCPOMATIC_WINDOWS
23 #include <GL/glew.h>
24 #endif
25
26 #include "gl_video_view.h"
27 #include "film_viewer.h"
28 #include "wx_util.h"
29 #include "lib/image.h"
30 #include "lib/dcpomatic_assert.h"
31 #include "lib/exceptions.h"
32 #include "lib/cross.h"
33 #include "lib/player_video.h"
34 #include "lib/butler.h"
35 #include <boost/bind/bind.hpp>
36 #include <iostream>
37
38 #ifdef DCPOMATIC_OSX
39 #define GL_DO_NOT_WARN_IF_MULTI_GL_VERSION_HEADERS_INCLUDED
40 #include <OpenGL/OpenGL.h>
41 #include <OpenGL/gl3.h>
42 #endif
43
44 #ifdef DCPOMATIC_LINUX
45 #include <GL/glu.h>
46 #include <GL/glext.h>
47 #endif
48
49 #ifdef DCPOMATIC_WINDOWS
50 #include <GL/glu.h>
51 #include <GL/wglext.h>
52 #endif
53
54
55 using std::cout;
56 using std::shared_ptr;
57 using std::string;
58 using boost::optional;
59 #if BOOST_VERSION >= 106100
60 using namespace boost::placeholders;
61 #endif
62
63
64 static void
65 check_gl_error (char const * last)
66 {
67         GLenum const e = glGetError ();
68         if (e != GL_NO_ERROR) {
69                 throw GLError (last, e);
70         }
71 }
72
73
74 GLVideoView::GLVideoView (FilmViewer* viewer, wxWindow *parent)
75         : VideoView (viewer)
76         , _context (nullptr)
77         , _have_storage (false)
78         , _vsync_enabled (false)
79         , _playing (false)
80         , _one_shot (false)
81 {
82         wxGLAttributes attributes;
83         /* We don't need a depth buffer, and indeed there is apparently a bug with Windows/Intel HD 630
84          * which puts green lines over the OpenGL display if you have a non-zero depth buffer size.
85          * https://community.intel.com/t5/Graphics/Request-for-details-on-Intel-HD-630-green-lines-in-OpenGL-apps/m-p/1202179
86          */
87         attributes.PlatformDefaults().MinRGBA(8, 8, 8, 8).DoubleBuffer().Depth(0).EndList();
88         _canvas = new wxGLCanvas (
89                 parent, attributes, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxFULL_REPAINT_ON_RESIZE
90         );
91         _canvas->Bind (wxEVT_PAINT, boost::bind(&GLVideoView::update, this));
92         _canvas->Bind (wxEVT_SIZE, boost::bind(&GLVideoView::size_changed, this, _1));
93
94         _canvas->Bind (wxEVT_TIMER, boost::bind(&GLVideoView::check_for_butler_errors, this));
95         _timer.reset (new wxTimer(_canvas));
96         _timer->Start (2000);
97 }
98
99
100 void
101 GLVideoView::size_changed (wxSizeEvent const& ev)
102 {
103         _canvas_size = ev.GetSize ();
104         Sized ();
105 }
106
107
108
109 GLVideoView::~GLVideoView ()
110 {
111         boost::this_thread::disable_interruption dis;
112
113         try {
114                 _thread.interrupt ();
115                 _thread.join ();
116         } catch (...) {}
117
118         glDeleteTextures (1, &_texture);
119 }
120
121 void
122 GLVideoView::check_for_butler_errors ()
123 {
124         if (!_viewer->butler()) {
125                 return;
126         }
127
128         try {
129                 _viewer->butler()->rethrow ();
130         } catch (DecodeError& e) {
131                 error_dialog (get(), e.what());
132         } catch (dcp::ReadError& e) {
133                 error_dialog (get(), wxString::Format(_("Could not read DCP: %s"), std_to_wx(e.what())));
134         }
135 }
136
137
138 /** Called from the UI thread */
139 void
140 GLVideoView::update ()
141 {
142         if (!_canvas->IsShownOnScreen()) {
143                 return;
144         }
145
146         /* It appears important to do this from the GUI thread; if we do it from the GL thread
147          * on Linux we get strange failures to create the context for any version of GL higher
148          * than 3.2.
149          */
150         ensure_context ();
151
152 #ifdef DCPOMATIC_OSX
153         /* macOS gives errors if we don't do this (and therefore [NSOpenGLContext setView:]) from the main thread */
154         if (!_setup_shaders_done) {
155                 setup_shaders ();
156                 _setup_shaders_done = true;
157         }
158 #endif
159
160         if (!_thread.joinable()) {
161                 _thread = boost::thread (boost::bind(&GLVideoView::thread, this));
162         }
163
164         request_one_shot ();
165
166         rethrow ();
167 }
168
169
170 static constexpr char vertex_source[] =
171 "#version 330 core\n"
172 "\n"
173 "layout (location = 0) in vec3 in_pos;\n"
174 "layout (location = 1) in vec2 in_tex_coord;\n"
175 "\n"
176 "out vec2 TexCoord;\n"
177 "\n"
178 "void main()\n"
179 "{\n"
180 "       gl_Position = vec4(in_pos, 1.0);\n"
181 "       TexCoord = in_tex_coord;\n"
182 "}\n";
183
184
185 /* Bicubic interpolation stolen from https://stackoverflow.com/questions/13501081/efficient-bicubic-filtering-code-in-glsl */
186 static constexpr char fragment_source[] =
187 "#version 330 core\n"
188 "\n"
189 "in vec2 TexCoord;\n"
190 "\n"
191 "uniform sampler2D texture_sampler;\n"
192 "uniform int draw_border;\n"
193 "uniform vec4 border_colour;\n"
194 "\n"
195 "out vec4 FragColor;\n"
196 "\n"
197 "vec4 cubic(float x)\n"
198 "{\n"
199 "    float x2 = x * x;\n"
200 "    float x3 = x2 * x;\n"
201 "    vec4 w;\n"
202 "    w.x =     -x3 + 3 * x2 - 3 * x + 1;\n"
203 "    w.y =  3 * x3 - 6 * x2         + 4;\n"
204 "    w.z = -3 * x3 + 3 * x2 + 3 * x + 1;\n"
205 "    w.w =  x3;\n"
206 "    return w / 6.f;\n"
207 "}\n"
208 "\n"
209 "vec4 texture_bicubic(sampler2D sampler, vec2 tex_coords)\n"
210 "{\n"
211 "   vec2 tex_size = textureSize(sampler, 0);\n"
212 "   vec2 inv_tex_size = 1.0 / tex_size;\n"
213 "\n"
214 "   tex_coords = tex_coords * tex_size - 0.5;\n"
215 "\n"
216 "   vec2 fxy = fract(tex_coords);\n"
217 "   tex_coords -= fxy;\n"
218 "\n"
219 "   vec4 xcubic = cubic(fxy.x);\n"
220 "   vec4 ycubic = cubic(fxy.y);\n"
221 "\n"
222 "   vec4 c = tex_coords.xxyy + vec2 (-0.5, +1.5).xyxy;\n"
223 "\n"
224 "   vec4 s = vec4(xcubic.xz + xcubic.yw, ycubic.xz + ycubic.yw);\n"
225 "   vec4 offset = c + vec4 (xcubic.yw, ycubic.yw) / s;\n"
226 "\n"
227 "   offset *= inv_tex_size.xxyy;\n"
228 "\n"
229 "   vec4 sample0 = texture(sampler, offset.xz);\n"
230 "   vec4 sample1 = texture(sampler, offset.yz);\n"
231 "   vec4 sample2 = texture(sampler, offset.xw);\n"
232 "   vec4 sample3 = texture(sampler, offset.yw);\n"
233 "\n"
234 "   float sx = s.x / (s.x + s.y);\n"
235 "   float sy = s.z / (s.z + s.w);\n"
236 "\n"
237 "   return mix(\n"
238 "          mix(sample3, sample2, sx), mix(sample1, sample0, sx)\n"
239 "          , sy);\n"
240 "}\n"
241 "\n"
242 "void main()\n"
243 "{\n"
244 "       if (draw_border == 1) {\n"
245 "               FragColor = border_colour;\n"
246 "       } else {\n"
247 "               FragColor = texture_bicubic(texture_sampler, TexCoord);\n"
248 "       }\n"
249 "}\n";
250
251
252 void
253 GLVideoView::ensure_context ()
254 {
255         if (!_context) {
256                 wxGLContextAttrs attrs;
257                 attrs.PlatformDefaults().CoreProfile().OGLVersion(4, 1).EndList();
258                 _context = new wxGLContext (_canvas, nullptr, &attrs);
259                 if (!_context->IsOK()) {
260                         throw GLError ("Making GL context", -1);
261                 }
262         }
263 }
264
265 void
266 GLVideoView::setup_shaders ()
267 {
268         DCPOMATIC_ASSERT (_canvas);
269         DCPOMATIC_ASSERT (_context);
270         auto r = _canvas->SetCurrent (*_context);
271         DCPOMATIC_ASSERT (r);
272
273 #ifdef DCPOMATIC_WINDOWS
274         r = glewInit();
275         if (r != GLEW_OK) {
276                 throw GLError(reinterpret_cast<char const*>(glewGetErrorString(r)));
277         }
278 #endif
279
280         auto get_information = [this](GLenum name) {
281                 auto s = glGetString (name);
282                 if (s) {
283                         _information[name] = std::string (reinterpret_cast<char const *>(s));
284                 }
285         };
286
287         get_information (GL_VENDOR);
288         get_information (GL_RENDERER);
289         get_information (GL_VERSION);
290         get_information (GL_SHADING_LANGUAGE_VERSION);
291
292         unsigned int indices[] = {
293                 0, 1, 3, // texture triangle #1
294                 1, 2, 3, // texture triangle #2
295                 4, 5,    // border line #1
296                 5, 6,    // border line #2
297                 6, 7,    // border line #3
298                 7, 4,    // border line #4
299         };
300
301         glGenVertexArrays(1, &_vao);
302         check_gl_error ("glGenVertexArrays");
303         GLuint vbo;
304         glGenBuffers(1, &vbo);
305         check_gl_error ("glGenBuffers");
306         GLuint ebo;
307         glGenBuffers(1, &ebo);
308         check_gl_error ("glGenBuffers");
309
310         glBindVertexArray(_vao);
311         check_gl_error ("glBindVertexArray");
312
313         glBindBuffer(GL_ARRAY_BUFFER, vbo);
314         check_gl_error ("glBindBuffer");
315
316         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
317         check_gl_error ("glBindBuffer");
318         glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
319         check_gl_error ("glBufferData");
320
321         /* position attribute to vertex shader (location = 0) */
322         glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), nullptr);
323         glEnableVertexAttribArray(0);
324         /* texture coord attribute to vertex shader (location = 1) */
325         glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), reinterpret_cast<void*>(3 * sizeof(float)));
326         glEnableVertexAttribArray(1);
327         check_gl_error ("glEnableVertexAttribArray");
328
329         auto compile = [](GLenum type, char const* source) -> GLuint {
330                 auto shader = glCreateShader(type);
331                 DCPOMATIC_ASSERT (shader);
332                 GLchar const * src[] = { static_cast<GLchar const *>(source) };
333                 glShaderSource(shader, 1, src, nullptr);
334                 check_gl_error ("glShaderSource");
335                 glCompileShader(shader);
336                 check_gl_error ("glCompileShader");
337                 GLint ok;
338                 glGetShaderiv(shader, GL_COMPILE_STATUS, &ok);
339                 if (!ok) {
340                         GLint log_length;
341                         glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
342                         string log;
343                         if (log_length > 0) {
344                                 char* log_char = new char[log_length];
345                                 glGetShaderInfoLog(shader, log_length, nullptr, log_char);
346                                 log = string(log_char);
347                                 delete[] log_char;
348                         }
349                         glDeleteShader(shader);
350                         throw GLError(String::compose("Could not compile shader (%1)", log).c_str(), -1);
351                 }
352                 return shader;
353         };
354
355         auto vertex_shader = compile (GL_VERTEX_SHADER, vertex_source);
356         auto fragment_shader = compile (GL_FRAGMENT_SHADER, fragment_source);
357
358         auto program = glCreateProgram();
359         check_gl_error ("glCreateProgram");
360         glAttachShader (program, vertex_shader);
361         check_gl_error ("glAttachShader");
362         glAttachShader (program, fragment_shader);
363         check_gl_error ("glAttachShader");
364         glLinkProgram (program);
365         check_gl_error ("glLinkProgram");
366         GLint ok;
367         glGetProgramiv (program, GL_LINK_STATUS, &ok);
368         if (!ok) {
369                 GLint log_length;
370                 glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
371                 string log;
372                 if (log_length > 0) {
373                         char* log_char = new char[log_length];
374                         glGetProgramInfoLog(program, log_length, nullptr, log_char);
375                         log = string(log_char);
376                         delete[] log_char;
377                 }
378                 glDeleteProgram (program);
379                 throw GLError(String::compose("Could not link shader (%1)", log).c_str(), -1);
380         }
381         glDeleteShader (vertex_shader);
382         glDeleteShader (fragment_shader);
383
384         glUseProgram (program);
385
386         _draw_border = glGetUniformLocation (program, "draw_border");
387         check_gl_error ("glGetUniformLocation");
388         set_border_colour (program);
389
390         glLineWidth (2.0f);
391 }
392
393
394 void
395 GLVideoView::set_border_colour (GLuint program)
396 {
397         auto uniform = glGetUniformLocation (program, "border_colour");
398         check_gl_error ("glGetUniformLocation");
399         auto colour = outline_content_colour ();
400         glUniform4f (uniform, colour.Red() / 255.0f, colour.Green() / 255.0f, colour.Blue() / 255.0f, 1.0f);
401         check_gl_error ("glUniform4f");
402 }
403
404
405 void
406 GLVideoView::draw (Position<int>, dcp::Size)
407 {
408         auto pad = pad_colour();
409         glClearColor(pad.Red() / 255.0, pad.Green() / 255.0, pad.Blue() / 255.0, 1.0);
410         glClear (GL_COLOR_BUFFER_BIT);
411         check_gl_error ("glClear");
412
413         auto const size = _canvas_size.load();
414         int const width = size.GetWidth();
415         int const height = size.GetHeight();
416
417         if (width < 64 || height < 0) {
418                 return;
419         }
420
421         glViewport (0, 0, width, height);
422         check_gl_error ("glViewport");
423
424         glBindTexture(GL_TEXTURE_2D, _texture);
425         glBindVertexArray(_vao);
426         check_gl_error ("glBindVertexArray");
427         glUniform1i(_draw_border, 0);
428         glDrawElements (GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
429         if (_viewer->outline_content()) {
430                 glUniform1i(_draw_border, 1);
431                 glDrawElements (GL_LINES, 8, GL_UNSIGNED_INT, reinterpret_cast<void*>(6 * sizeof(int)));
432                 check_gl_error ("glDrawElements");
433         }
434
435         glFlush();
436         check_gl_error ("glFlush");
437
438         _canvas->SwapBuffers();
439 }
440
441
442 void
443 GLVideoView::set_image (shared_ptr<const Image> image)
444 {
445         if (!image) {
446                 _size = optional<dcp::Size>();
447                 return;
448         }
449
450
451         DCPOMATIC_ASSERT (image->pixel_format() == AV_PIX_FMT_RGB24);
452         DCPOMATIC_ASSERT (!image->aligned());
453
454         if (image->size() != _size) {
455                 _have_storage = false;
456         }
457
458         _size = image->size ();
459         glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
460         check_gl_error ("glPixelStorei");
461
462         if (_have_storage) {
463                 glTexSubImage2D (GL_TEXTURE_2D, 0, 0, 0, _size->width, _size->height, GL_RGB, GL_UNSIGNED_BYTE, image->data()[0]);
464                 check_gl_error ("glTexSubImage2D");
465         } else {
466                 glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA8, _size->width, _size->height, 0, GL_RGB, GL_UNSIGNED_BYTE, image->data()[0]);
467                 check_gl_error ("glTexImage2D");
468
469                 auto const canvas_size = _canvas_size.load();
470                 int const canvas_width = canvas_size.GetWidth();
471                 int const canvas_height = canvas_size.GetHeight();
472
473                 float const image_x = float(_size->width) / canvas_width;
474                 float const image_y = float(_size->height) / canvas_height;
475
476                 auto x_pixels_to_gl = [canvas_width](int x) {
477                         return (x * 2.0f / canvas_width) - 1.0f;
478                 };
479
480                 auto y_pixels_to_gl = [canvas_height](int y) {
481                         return (y * 2.0f / canvas_height) - 1.0f;
482                 };
483
484                 auto inter_position = player_video().first->inter_position();
485                 auto inter_size = player_video().first->inter_size();
486
487                 float const border_x1 = x_pixels_to_gl (inter_position.x) + 1.0f - image_x;
488                 float const border_y1 = y_pixels_to_gl (inter_position.y) + 1.0f - image_y;
489                 float const border_x2 = x_pixels_to_gl (inter_position.x + inter_size.width) + 1.0f - image_x;
490                 float const border_y2 = y_pixels_to_gl (inter_position.y + inter_size.height) + 1.0f - image_y;
491
492                 float vertices[] = {
493                         // positions                  // texture coords
494                          image_x,   image_y,   0.0f,  1.0f, 0.0f,   // top right           (index 0)
495                          image_x,  -image_y,   0.0f,  1.0f, 1.0f,   // bottom right        (index 1)
496                         -image_x,  -image_y,   0.0f,  0.0f, 1.0f,   // bottom left         (index 2)
497                         -image_x,   image_y,   0.0f,  0.0f, 0.0f,   // top left            (index 3)
498                          border_x1, border_y1, 0.0f,  0.0f, 0.0f,   // border bottom left  (index 4)
499                          border_x1, border_y2, 0.0f,  0.0f, 0.0f,   // border top left     (index 5)
500                          border_x2, border_y2, 0.0f,  0.0f, 0.0f,   // border top right    (index 6)
501                          border_x2, border_y1, 0.0f,  0.0f, 0.0f,   // border bottom right (index 7)
502                 };
503
504                 /* Set the vertex shader's input data (GL_ARRAY_BUFFER) */
505                 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
506                 check_gl_error ("glBufferData");
507
508                 _have_storage = true;
509         }
510
511         glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
512         glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
513         check_gl_error ("glTexParameteri");
514
515         glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
516         glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
517         check_gl_error ("glTexParameterf");
518 }
519
520 void
521 GLVideoView::start ()
522 {
523         VideoView::start ();
524
525         boost::mutex::scoped_lock lm (_playing_mutex);
526         _playing = true;
527         _thread_work_condition.notify_all ();
528 }
529
530 void
531 GLVideoView::stop ()
532 {
533         boost::mutex::scoped_lock lm (_playing_mutex);
534         _playing = false;
535 }
536
537
538 void
539 GLVideoView::thread_playing ()
540 {
541         if (length() != dcpomatic::DCPTime()) {
542                 auto const next = position() + one_video_frame();
543
544                 if (next >= length()) {
545                         _viewer->finished ();
546                         return;
547                 }
548
549                 get_next_frame (false);
550                 set_image_and_draw ();
551         }
552
553         while (true) {
554                 optional<int> n = time_until_next_frame();
555                 if (!n || *n > 5) {
556                         break;
557                 }
558                 get_next_frame (true);
559                 add_dropped ();
560         }
561 }
562
563
564 void
565 GLVideoView::set_image_and_draw ()
566 {
567         auto pv = player_video().first;
568         if (pv) {
569                 set_image (pv->image(bind(&PlayerVideo::force, _1, AV_PIX_FMT_RGB24), VideoRange::FULL, false, true));
570                 draw (pv->inter_position(), pv->inter_size());
571                 _viewer->image_changed (pv);
572         }
573 }
574
575
576 void
577 GLVideoView::thread ()
578 try
579 {
580         start_of_thread ("GLVideoView");
581
582 #if defined(DCPOMATIC_OSX)
583         /* Without this we see errors like
584          * ../src/osx/cocoa/glcanvas.mm(194): assert ""context"" failed in SwapBuffers(): should have current context [in thread 700006970000]
585          */
586         WXGLSetCurrentContext (_context->GetWXGLContext());
587 #else
588         if (!_setup_shaders_done) {
589                 setup_shaders ();
590                 _setup_shaders_done = true;
591         }
592 #endif
593
594 #if defined(DCPOMATIC_LINUX) && defined(DCPOMATIC_HAVE_GLX_SWAP_INTERVAL_EXT)
595         if (_canvas->IsExtensionSupported("GLX_EXT_swap_control")) {
596                 /* Enable vsync */
597                 Display* dpy = wxGetX11Display();
598                 glXSwapIntervalEXT (dpy, DefaultScreen(dpy), 1);
599                 _vsync_enabled = true;
600         }
601 #endif
602
603 #ifdef DCPOMATIC_WINDOWS
604         if (_canvas->IsExtensionSupported("WGL_EXT_swap_control")) {
605                 /* Enable vsync */
606                 PFNWGLSWAPINTERVALEXTPROC swap = (PFNWGLSWAPINTERVALEXTPROC) wglGetProcAddress("wglSwapIntervalEXT");
607                 if (swap) {
608                         swap (1);
609                         _vsync_enabled = true;
610                 }
611         }
612
613 #endif
614
615 #ifdef DCPOMATIC_OSX
616         /* Enable vsync */
617         GLint swapInterval = 1;
618         CGLSetParameter (CGLGetCurrentContext(), kCGLCPSwapInterval, &swapInterval);
619         _vsync_enabled = true;
620 #endif
621
622         glGenTextures (1, &_texture);
623         check_gl_error ("glGenTextures");
624         glBindTexture (GL_TEXTURE_2D, _texture);
625         check_gl_error ("glBindTexture");
626
627         while (true) {
628                 boost::mutex::scoped_lock lm (_playing_mutex);
629                 while (!_playing && !_one_shot) {
630                         _thread_work_condition.wait (lm);
631                 }
632                 lm.unlock ();
633
634                 if (_playing) {
635                         thread_playing ();
636                 } else if (_one_shot) {
637                         _one_shot = false;
638                         set_image_and_draw ();
639                 }
640
641                 boost::this_thread::interruption_point ();
642                 dcpomatic_sleep_milliseconds (time_until_next_frame().get_value_or(0));
643         }
644
645         /* XXX: leaks _context, but that seems preferable to deleting it here
646          * without also deleting the wxGLCanvas.
647          */
648 }
649 catch (...)
650 {
651         store_current ();
652 }
653
654
655 VideoView::NextFrameResult
656 GLVideoView::display_next_frame (bool non_blocking)
657 {
658         NextFrameResult const r = get_next_frame (non_blocking);
659         request_one_shot ();
660         return r;
661 }
662
663
664 void
665 GLVideoView::request_one_shot ()
666 {
667         boost::mutex::scoped_lock lm (_playing_mutex);
668         _one_shot = true;
669         _thread_work_condition.notify_all ();
670 }
671