video-timer: add a test case for display at a constant frame rate
Add a test case that simulates the timing operaton that goes on when showing a constant frame rate stream like a video - each frame is shown at the VBlank interval that is closest to when it would ideally be timed. https://bugzilla.gnome.org/show_bug.cgi?id=685460
This commit is contained in:
Owen W. Taylor
328
tests/video-timer.c
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328
tests/video-timer.c
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#include <math.h>
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#include <gtk/gtk.h>
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#include "variable.h"
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typedef struct {
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gdouble angle;
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gint64 stream_time;
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gint64 clock_time;
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gint64 frame_counter;
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} FrameData;
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static FrameData *displayed_frame;
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static GtkWidget *window;
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static GList *past_frames;
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static Variable latency_error = VARIABLE_INIT;
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static int dropped_frames = 0;
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static int n_frames = 0;
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static int fps = 24;
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/* Thread-safe frame queue */
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#define MAX_QUEUE_LENGTH 5
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static GQueue *frame_queue;
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static GMutex frame_mutex;
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static GCond frame_cond;
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static void
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queue_frame (FrameData *frame_data)
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{
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g_mutex_lock (&frame_mutex);
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while (frame_queue->length == MAX_QUEUE_LENGTH)
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g_cond_wait (&frame_cond, &frame_mutex);
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g_queue_push_tail (frame_queue, frame_data);
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g_mutex_unlock (&frame_mutex);
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}
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static FrameData *
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unqueue_frame (void)
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{
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FrameData *frame_data;
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g_mutex_lock (&frame_mutex);
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if (frame_queue->length > 0)
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{
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frame_data = g_queue_pop_head (frame_queue);
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g_cond_signal (&frame_cond);
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}
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else
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{
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frame_data = NULL;
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}
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g_mutex_unlock (&frame_mutex);
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return frame_data;
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}
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static FrameData *
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peek_pending_frame (void)
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{
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FrameData *frame_data;
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g_mutex_lock (&frame_mutex);
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if (frame_queue->head)
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frame_data = frame_queue->head->data;
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else
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frame_data = NULL;
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g_mutex_unlock (&frame_mutex);
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return frame_data;
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}
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static FrameData *
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peek_next_frame (void)
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{
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FrameData *frame_data;
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g_mutex_lock (&frame_mutex);
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if (frame_queue->head && frame_queue->head->next)
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frame_data = frame_queue->head->next->data;
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else
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frame_data = NULL;
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g_mutex_unlock (&frame_mutex);
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return frame_data;
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}
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/* Frame producer thread */
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static gpointer
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create_frames_thread (gpointer data)
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{
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int frame_count = 0;
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while (TRUE)
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{
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FrameData *frame_data = g_slice_new0 (FrameData);
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frame_data->angle = 2 * M_PI * (frame_count % fps) / (double)fps;
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frame_data->stream_time = (G_GINT64_CONSTANT (1000000) * frame_count) / fps;
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queue_frame (frame_data);
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frame_count++;
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}
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return NULL;
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}
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/* Clock management */
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#define PRE_BUFFER_TIME 500000
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static gint64 start_time;
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static gint64
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stream_time_to_clock_time (gint64 stream_time)
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{
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return start_time + stream_time + PRE_BUFFER_TIME;
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}
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/* Drawing */
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static void
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on_window_draw (GtkWidget *widget,
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cairo_t *cr)
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{
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GdkRectangle allocation;
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double cx, cy, r;
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cairo_set_source_rgb (cr, 1., 1., 1.);
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cairo_paint (cr);
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cairo_set_source_rgb (cr, 0., 0., 0.);
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gtk_widget_get_allocation (widget, &allocation);
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cx = allocation.width / 2.;
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cy = allocation.height / 2.;
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r = MIN (allocation.width, allocation.height) / 2.;
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cairo_arc (cr, cx, cy, r,
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0, 2 * M_PI);
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cairo_stroke (cr);
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if (displayed_frame)
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{
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cairo_move_to (cr, cx, cy);
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cairo_line_to (cr,
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cx + r * cos(displayed_frame->angle - M_PI / 2),
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cy + r * sin(displayed_frame->angle - M_PI / 2));
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cairo_stroke (cr);
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if (displayed_frame->frame_counter == 0)
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{
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GdkFrameClock *frame_clock = gtk_widget_get_frame_clock (window);
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GdkFrameHistory *history = gdk_frame_clock_get_history (frame_clock);
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displayed_frame->frame_counter = gdk_frame_history_get_frame_counter (history);
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}
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}
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}
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static void
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collect_old_frames (void)
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{
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GdkFrameClock *frame_clock = gtk_widget_get_frame_clock (window);
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GdkFrameHistory *history = gdk_frame_clock_get_history (frame_clock);
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GList *l, *l_next;
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for (l = past_frames; l; l = l_next)
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{
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FrameData *frame_data = l->data;
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gboolean remove = FALSE;
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l_next = l->next;
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GdkFrameTimings *timings = gdk_frame_history_get_timings (history,
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frame_data->frame_counter);
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if (timings == NULL)
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{
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remove = TRUE;
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}
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else if (gdk_frame_timings_get_complete (timings))
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{
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gint64 presentation_time = gdk_frame_timings_get_presentation_time (timings);
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if (presentation_time)
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variable_add (&latency_error,
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presentation_time - frame_data->clock_time);
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remove = TRUE;
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}
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if (remove)
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{
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past_frames = g_list_delete_link (past_frames, l);
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g_slice_free (FrameData, frame_data);
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}
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}
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}
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static void
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print_statistics (void)
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{
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gint64 now = g_get_monotonic_time ();
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static gint64 last_print_time = 0;
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if (last_print_time == 0)
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last_print_time = now;
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else if (now -last_print_time > 5000000)
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{
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g_print ("dropped_frames: %d/%d\n",
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dropped_frames, n_frames);
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g_print ("collected_frames: %g/%d\n",
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latency_error.weight, n_frames);
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g_print ("latency_error: %g +/- %g\n",
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variable_mean (&latency_error),
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variable_standard_deviation (&latency_error));
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variable_reset (&latency_error);
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dropped_frames = 0;
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n_frames = 0;
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last_print_time = now;
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}
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}
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static void
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on_update (GdkFrameClock *frame_clock,
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gpointer data)
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{
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GdkFrameTimings *timings = gdk_frame_clock_get_current_frame_timings (frame_clock);
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gint64 frame_time = gdk_frame_timings_get_frame_time (timings);
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gint64 predicted_presentation_time = gdk_frame_timings_get_predicted_presentation_time (timings);
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gint64 refresh_interval;
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FrameData *pending_frame;
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if (start_time == 0)
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start_time = frame_time;
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gdk_frame_clock_get_refresh_info (frame_clock, frame_time,
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&refresh_interval, NULL);
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pending_frame = peek_pending_frame ();
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if (stream_time_to_clock_time (pending_frame->stream_time)
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< predicted_presentation_time + refresh_interval / 2)
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{
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while (TRUE)
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{
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FrameData *next_frame = peek_next_frame ();
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if (next_frame &&
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stream_time_to_clock_time (next_frame->stream_time)
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< predicted_presentation_time + refresh_interval / 2)
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{
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g_slice_free (FrameData, unqueue_frame ());
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n_frames++;
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dropped_frames++;
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pending_frame = next_frame;
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}
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else
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break;
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}
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if (displayed_frame)
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past_frames = g_list_prepend (past_frames, displayed_frame);
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n_frames++;
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displayed_frame = unqueue_frame ();
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displayed_frame->clock_time = stream_time_to_clock_time (displayed_frame->stream_time);
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displayed_frame->frame_counter = gdk_frame_timings_get_frame_counter (timings);
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collect_old_frames ();
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print_statistics ();
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gtk_widget_queue_draw (window);
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}
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gdk_frame_clock_request_phase (frame_clock, GDK_FRAME_CLOCK_PHASE_UPDATE);
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}
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static GOptionEntry options[] = {
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{ "fps", 'f', 0, G_OPTION_ARG_INT, &fps, "Frame rate", "FPS" },
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{ NULL }
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};
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int
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main(int argc, char **argv)
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{
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GError *error = NULL;
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GdkFrameClock *frame_clock;
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if (!gtk_init_with_args (&argc, &argv, "",
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options, NULL, &error))
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{
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g_printerr ("Option parsing failed: %s\n", error->message);
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return 1;
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}
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window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
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gtk_widget_set_app_paintable (window, TRUE);
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gtk_window_set_default_size (GTK_WINDOW (window), 300, 300);
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g_signal_connect (window, "draw",
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G_CALLBACK (on_window_draw), NULL);
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g_signal_connect (window, "destroy",
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G_CALLBACK (gtk_main_quit), NULL);
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gtk_widget_show (window);
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frame_queue = g_queue_new ();
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g_mutex_init (&frame_mutex);
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g_cond_init (&frame_cond);
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g_thread_new ("Create Frames", create_frames_thread, NULL);
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frame_clock = gtk_widget_get_frame_clock (window);
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g_signal_connect (frame_clock, "update",
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G_CALLBACK (on_update), NULL);
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gdk_frame_clock_request_phase (frame_clock, GDK_FRAME_CLOCK_PHASE_UPDATE);
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gtk_main ();
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return 0;
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}
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