displays: changed api for mainloop

- removed `needs_mainloop` attribute and deduce if mainloop is needed
  from the presence of _run callback (the information is now redundant
  only displays needing/running mainloop should announce _run callback)

- run the custom mainloop (currently only Syphon!) only when display
  doesn't run its mainloop. This allows running Syphon and GL/SDL
  display because it connects to the display mainloop.

src/aja_win32_stub.cpp

@@ -89,7 +89,6 @@ static const struct video_display_info display_aja_info = {
         display_aja_get_property,
         display_aja_put_audio_frame,
         display_aja_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/host.cpp

@@ -827,6 +827,11 @@ void print_video_codecs(void) {
         cout << "\nLegend:\n" << " I - interframe codec\n";
 }
 
+/**
+ * Registers mainloop that will be run if display-owned mainloop isn't run.
+ * Currently this is only used by Syphon, that either connects to display event
+ * loop and if there isn't any, it runs its own.
+ */
 bool register_mainloop(mainloop_t m, void *u)
 {
         if (mainloop) {

src/host.h

@@ -102,6 +102,7 @@ extern unsigned int cuda_devices_count;
 #define MODE_RECEIVER (1U<<1U)
 
 typedef void (*mainloop_t)(void *);
+/// mainloop to be run if display mainloop isn't run
 extern mainloop_t mainloop;
 extern void *mainloop_udata;
 

src/main.cpp

@@ -1658,17 +1658,7 @@ int main(int argc, char *argv[])
                 control_start(control);
                 kc.start();
 
-                if(mainloop) {
-                        if (display_needs_mainloop(uv.display_device)) {
-                                throw string("Cannot run display when "
-                                                "another mainloop registered!\n");
-                        }
-                        display_run_new_thread(uv.display_device);
-                        mainloop(mainloop_udata);
-                        display_join(uv.display_device);
-                } else {
-                        display_run_this_thread(uv.display_device);
-                }
+                display_run_mainloop(uv.display_device);
 
         } catch (ug_no_error const &e) {
                 exit_uv(0);

src/video_display.c

@@ -195,13 +195,7 @@ void display_done(struct display *d)
 bool display_needs_mainloop(struct display *d)
 {
         assert(d->magic == DISPLAY_MAGIC);
-        if (d->funcs->needs_mainloop == DISPLAY_NEEDS_MAINLOOP) {
-                return true;
-        }
-        if (d->funcs->needs_mainloop == DISPLAY_DOESNT_NEED_MAINLOOP) {
-                return false;
-        }
-        return d->funcs->needs_mainloop(d->state);
+        return d->funcs->run != NULL;
 }
 
 #define CHECK(cmd) do { \
@@ -225,29 +219,25 @@ static void *display_run_helper(void *args)
 /**
  * @brief Display mainloop function.
  *
- * This function runs the display in the thread it is called from
- * and blocks until the display stops.
+ * It is intended for GUI displays (GL/SDL), which run main event loop and need
+ * to be run from main thread of the program (macOS).
  *
- * It is mainly intended for GUI displays (GL/SDL), which usually need
- * to be run from main thread of the * program (OS X).
- *
- * The function blocks while the display runs.
  * The display can be terminated by passing a poisoned pill (frame == NULL)
  * using the display_put_frame() call.
  *
  * @param d display to be run
  */
-void display_run_this_thread(struct display *d)
+void display_run_mainloop(struct display *d)
 {
         assert(d->magic == DISPLAY_MAGIC);
         if (d->funcs->run) {
                 d->funcs->run(d->state);
+        } else if (mainloop) {
+                mainloop(mainloop_udata);
         }
 }
 
 /**
- * @brief Display mainloop function.
- *
  * This function runs the display in a new thread and does not block.
  *
  * It should not be used for GUI displays (GL/SDL), which usually need

src/video_display.h

@@ -59,7 +59,7 @@
  * Thread #1 (main thread)
  * @code{.c}
  * d = ininitalize_video_display(...);
- * display_run_this_thread(d);
+ * display_run_mainloop(d);
  * display_done(d);
  *
  * Thread #2
@@ -142,18 +142,14 @@ enum display_prop_vid_mode {
 };
 /// @}
 
-#define VIDEO_DISPLAY_ABI_VERSION 17
-
-typedef bool (*display_needs_mainloop_t)(void *);
-#define DISPLAY_DOESNT_NEED_MAINLOOP ((display_needs_mainloop_t) 0x00)
-#define DISPLAY_NEEDS_MAINLOOP ((display_needs_mainloop_t) 0x01)
+#define VIDEO_DISPLAY_ABI_VERSION 18
 
 #define DISPLAY_NO_GENERIC_FPS_INDICATOR ((const char *) 0x00)
 
 struct video_display_info {
         device_probe_func         probe;
         void                   *(*init) (struct module *parent, const char *fmt, unsigned int flags);
-        void                    (*run) (void *state);                                               ///< may be NULL
+        void                    (*run) (void *state);                                               ///< callback to display main event loop; may be NULL
         void                    (*done) (void *state);
         struct video_frame     *(*getf) (void *state);
         /// @param timeout_ns display is supposed immplement the PUTF_* macros, numerical timeout is seldom used (but double-framerate postprocess can use that)
@@ -163,7 +159,6 @@ struct video_display_info {
         void                    (*put_audio_frame) (void *state, const struct audio_frame *frame);  ///< may be NULL
         int                     (*reconfigure_audio) (void *state, int quant_samples, int channels, ///< may be NULL
                         int sample_rate);
-        display_needs_mainloop_t needs_mainloop;
         const char             *generic_fps_indicator_prefix; ///< NO_GENERIC_FPS_INDICATOR or pointer to preferred module name
 };
 
@@ -179,7 +174,7 @@ int                      initialize_video_display(struct module *parent,
                 /* not_null */ const char *requested_display, /* not_null */ const char *fmt,
                 unsigned int flags, const char *postprocess, /* not_null */ struct display **out);
 bool                     display_needs_mainloop(struct display *d);
-void                     display_run_this_thread(struct display *d);
+void                     display_run_mainloop(struct display *d);
 void                     display_run_new_thread(struct display *d);
 void                     display_join(struct display *d);
 void 	                 display_done(struct display *d);

src/video_display/aggregate.c

@@ -390,7 +390,6 @@ static const struct video_display_info display_aggregate_info = {
         display_aggregate_get_property,
         display_aggregate_put_audio_frame,
         display_aggregate_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/aja.cpp

@@ -1105,7 +1105,6 @@ static const struct video_display_info display_aja_info = {
         display_aja_get_property,
         display_aja_put_audio_frame,
         display_aja_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/blend.cpp

@@ -424,7 +424,6 @@ static const struct video_display_info display_blend_info = {
         display_blend_get_property,
         display_blend_put_audio_frame,
         display_blend_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/bluefish444.cpp

@@ -1035,7 +1035,6 @@ static const struct video_display_info display_bluefish444_info = {
         display_bluefish444_get_property,
         display_bluefish444_put_audio_frame,
         display_bluefish444_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/caca.c

@@ -314,7 +314,6 @@ static const void *display_caca_info_get() {
                 display_caca_get_property,
                 NULL,
                 NULL,
-                DISPLAY_DOESNT_NEED_MAINLOOP,
                 DISPLAY_NO_GENERIC_FPS_INDICATOR,
         };
         const char *display = getenv("DISPLAY");

src/video_display/conference.cpp

@@ -635,7 +635,7 @@ static void display_conference_run(void *state)
 
         std::thread worker = std::thread(display_conference_worker, s);
 
-        display_run_this_thread(s->real_display.get());
+        display_run_mainloop(s->real_display.get());
 
         worker.join();
 }
@@ -731,12 +731,6 @@ static int display_conference_putf(void *state, struct video_frame *frame, long
         return 0;
 }
 
-static auto display_conference_needs_mainloop(void *state)
-{
-        auto s = static_cast<struct state_conference *>(state)->common;
-        return display_needs_mainloop(s->real_display.get());
-}
-
 static void display_conference_probe(struct device_info **available_cards, int *count, void (**deleter)(void *)) {
         UNUSED(deleter);
         *available_cards = nullptr;
@@ -754,7 +748,6 @@ static const struct video_display_info display_conference_info = {
         display_conference_get_property,
         display_conference_put_audio_frame,
         display_conference_reconfigure_audio,
-        display_conference_needs_mainloop,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/decklink.cpp

@@ -2029,7 +2029,6 @@ static const struct video_display_info display_decklink_info = {
         display_decklink_get_property,
         display_decklink_put_audio_frame,
         display_decklink_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         MOD_NAME,
 };
 

src/video_display/deltacast.cpp

@@ -559,7 +559,6 @@ static const struct video_display_info display_deltacast_info = {
         display_deltacast_get_property,
         display_deltacast_put_audio_frame,
         display_deltacast_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/dummy.c

@@ -291,7 +291,6 @@ static const struct video_display_info display_dummy_info = {
         display_dummy_get_property,
         NULL, // _put_audio_frame
         NULL, // _reconfigure_audio
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         MOD_NAME,
 };
 

src/video_display/dump.c

@@ -189,7 +189,6 @@ static const struct video_display_info display_dump_info = {
         display_dump_get_property,
         NULL, // _put_audio_frame
         NULL, // _reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         MOD_NAME,
 };
 

src/video_display/dvs.c

@@ -985,7 +985,6 @@ static const struct video_display_info display_dvs_info = {
         display_dvs_get_property,
         display_dvs_put_audio_frame,
         display_dvs_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/gl.cpp

@@ -1944,7 +1944,6 @@ static const struct video_display_info display_gl_info = {
         display_gl_get_property,
         display_gl_put_audio_frame,
         display_gl_reconfigure_audio,
-        DISPLAY_NEEDS_MAINLOOP, // many GLFW functions must be called from main thread (notably glfwPollEvents())
         MOD_NAME,
 };
 

src/video_display/multiplier.cpp

@@ -208,7 +208,7 @@ static void display_multiplier_run(void *state)
 
         s->worker_thread = thread(display_multiplier_worker, state);
 
-        display_run_this_thread(s->displays[0].get());
+        display_run_mainloop(s->displays[0].get());
 
         s->worker_thread.join();
         for (size_t i = 1; i < s->displays.size(); i++) {
@@ -300,12 +300,6 @@ static int display_multiplier_reconfigure_audio(void *state, int quant_samples,
         return display_reconfigure_audio(s->common->displays.at(0).get(), quant_samples, channels, sample_rate);
 }
 
-static auto display_multiplier_needs_mainloop(void *state)
-{
-        auto s = static_cast<struct state_multiplier *>(state)->common;
-        return !s->displays.empty() && display_needs_mainloop(s->displays[0].get());
-}
-
 static void display_multiplier_probe(struct device_info **available_cards, int *count, void (**deleter)(void *)) {
         UNUSED(deleter);
         *available_cards = nullptr;
@@ -323,7 +317,6 @@ static const struct video_display_info display_multiplier_info = {
         display_multiplier_get_property,
         display_multiplier_put_audio_frame,
         display_multiplier_reconfigure_audio,
-        display_multiplier_needs_mainloop,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/ndi.c

@@ -454,7 +454,6 @@ static const struct video_display_info display_ndi_info = {
         display_ndi_get_property,
         display_ndi_put_audio_frame,
         display_ndi_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         MOD_NAME,
 };
 

src/video_display/null.c

@@ -148,7 +148,6 @@ static const struct video_display_info display_null_info = {
         display_null_get_property,
         display_null_put_audio_frame,
         display_null_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/openxr_gl.cpp

@@ -1160,7 +1160,6 @@ static const struct video_display_info openxr_gl_info = {
         display_xrgl_get_property,
         NULL,
         NULL,
-        DISPLAY_NEEDS_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/pano_gl.cpp

@@ -377,7 +377,6 @@ static const struct video_display_info display_panogl_info = {
         display_panogl_get_property,
         NULL,
         NULL,
-        DISPLAY_NEEDS_MAINLOOP,
         MOD_NAME,
 };
 

src/video_display/pipe.cpp

@@ -299,7 +299,6 @@ static const struct video_display_info display_pipe_info = {
         display_pipe_get_property,
         display_pipe_put_audio_frame,
         display_pipe_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/rpi4_out.cpp

@@ -658,7 +658,6 @@ static const struct video_display_info display_rpi4_info = {
         display_rpi4_get_property,
         display_rpi4_put_audio_frame,
         display_rpi4_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         "[RPi display] ",
 };
 

src/video_display/sage.cpp

@@ -571,7 +571,6 @@ static const struct video_display_info display_sage_info = {
         display_sage_get_property,
         display_sage_put_audio_frame,
         display_sage_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/sdl.cpp

@@ -785,11 +785,6 @@ static const struct video_display_info display_sdl_info = {
         display_sdl_get_property,
         display_sdl_put_audio_frame,
         display_sdl_reconfigure_audio,
-#ifdef __APPLE__
-        DISPLAY_NEEDS_MAINLOOP,
-#else
-        DISPLAY_DOESNT_NEED_MAINLOOP,
-#endif
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/sdl2.c

@@ -809,7 +809,6 @@ static const struct video_display_info display_sdl2_info = {
         display_sdl2_get_property,
         NULL,
         NULL,
-        DISPLAY_NEEDS_MAINLOOP,
         MOD_NAME,
 };
 

src/video_display/unix_sock.cpp

@@ -355,7 +355,6 @@ static const struct video_display_info display_unix_sock_info = {
         display_unix_sock_get_property,
         display_unix_sock_put_audio_frame,
         display_unix_sock_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         MOD_NAME,
 };
 
@@ -370,7 +369,6 @@ static const struct video_display_info display_preview_info = {
         display_unix_sock_get_property,
         display_unix_sock_put_audio_frame,
         display_unix_sock_reconfigure_audio,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         "[unix sock preview] ",
 };
 

src/video_display/v4l2.c

@@ -334,7 +334,6 @@ static const struct video_display_info display_v4l2_info = {
         display_v4l2_get_property,
         NULL,
         NULL,
-        DISPLAY_DOESNT_NEED_MAINLOOP,
         DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 

src/video_display/vulkan/vulkan_sdl2.cpp

@@ -1001,8 +1001,7 @@ const video_display_info display_vulkan_info = {
         display_vulkan_get_property,
         display_vulkan_put_audio_frame,
         display_vulkan_reconfigure_audio,
-        DISPLAY_NEEDS_MAINLOOP,
-        nullptr,
+        DISPLAY_NO_GENERIC_FPS_INDICATOR,
 };
 
 } // namespace