[FFmpeg-devel] [PATCH] fftools/ffplay: use SDL_WaitEvent instead of SDL_PeepEvents while paused

[Bolshoy Toster]

Currently, when ffplay is paused, it still constantly polls for events 
at the
REFRESH_RATE (100 times per second). This leads to a high (5-10% on the 
latest
commit, using SDL2 2.28.5-1) CPU usage, when it should be idle.

This commit changes this behaviour to use SDL_WaitEvent while paused, 
allowing
ffplay to use less (0-5% under X11) CPU time while paused on supported 
platforms
(windows, X11 and wayland) with SDL versions >=2.0.16.

This has the side effect of only running the refresh loop when there's 
an event,
preventing the cursor from being hidden while paused.

Signed-off-by: bolshoytoster <toasterbig at gmail.com>
---
  fftools/ffplay.c | 31 ++++++++++++++++++++-----------
  1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/fftools/ffplay.c b/fftools/ffplay.c
index d8c69e1..7814589 100644
--- a/fftools/ffplay.c
+++ b/fftools/ffplay.c
@@ -3221,20 +3221,29 @@ static void toggle_audio_display(VideoState *is)
      }
  }
  +static void refresh(VideoState *is, double *remaining_time) {
+    if (!cursor_hidden && av_gettime_relative() - cursor_last_shown > 
CURSOR_HIDE_DELAY) {
+        SDL_ShowCursor(0);
+        cursor_hidden = 1;
+    }
+    if (*remaining_time > 0.0)
+        av_usleep((int64_t)(*remaining_time * 1000000.0));
+    *remaining_time = REFRESH_RATE;
+    if (is->show_mode != SHOW_MODE_NONE && (!is->paused || 
is->force_refresh))
+        video_refresh(is, remaining_time);
+}
+
  static void refresh_loop_wait_event(VideoState *is, SDL_Event *event) {
      double remaining_time = 0.0;
-    SDL_PumpEvents();
-    while (!SDL_PeepEvents(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, 
SDL_LASTEVENT)) {
-        if (!cursor_hidden && av_gettime_relative() - cursor_last_shown 
 > CURSOR_HIDE_DELAY) {
-            SDL_ShowCursor(0);
-            cursor_hidden = 1;
-        }
-        if (remaining_time > 0.0)
-            av_usleep((int64_t)(remaining_time * 1000000.0));
-        remaining_time = REFRESH_RATE;
-        if (is->show_mode != SHOW_MODE_NONE && (!is->paused || 
is->force_refresh))
-            video_refresh(is, &remaining_time);
+    if (is->paused) {
+        refresh(is, &remaining_time);
+        SDL_WaitEvent(event);
+    } else {
          SDL_PumpEvents();
+        while (!SDL_PeepEvents(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, 
SDL_LASTEVENT)) {
+            refresh(is, &remaining_time);
+            SDL_PumpEvents();
+        }
      }
  }
  -- 2.42.1