Add FPS counter

Remove frame counter from scrcpy.c and add a new FPS counter, logging as
INFO the measured frame rate every second (on new frame).

app/meson.build

@@ -6,6 +6,7 @@ src = [
     'src/convert.c',
     'src/decoder.c',
     'src/device.c',
+    'src/fpscounter.c',
     'src/frames.c',
     'src/lockutil.c',
     'src/netutil.c',

app/src/fpscounter.c

@@ -0,0 +1,62 @@
+#include "fpscounter.h"
+
+#include <SDL2/SDL_timer.h>
+
+#include "log.h"
+
+void fps_counter_init(struct fps_counter *counter) {
+    counter->started = SDL_FALSE;
+    // no need to initialize the other fields, they are meaningful only when
+    // started is true
+}
+
+void fps_counter_start(struct fps_counter *counter) {
+    counter->started = SDL_TRUE;
+    counter->slice_start = SDL_GetTicks();
+    counter->nr_rendered = 0;
+#ifdef SKIP_FRAMES
+    counter->nr_skipped = 0;
+#endif
+}
+
+void fps_counter_stop(struct fps_counter *counter) {
+    counter->started = SDL_FALSE;
+}
+
+static void display_fps(struct fps_counter *counter) {
+#ifdef SKIP_FRAMES
+    if (counter->nr_skipped) {
+        LOGI("%d fps (+%d frames skipped)", counter->nr_rendered, counter->nr_skipped);
+    } else {
+#endif
+    LOGI("%d fps", counter->nr_rendered);
+#ifdef SKIP_FRAMES
+    }
+#endif
+}
+
+static void check_expired(struct fps_counter *counter) {
+    Uint32 now = SDL_GetTicks();
+    if (now - counter->slice_start >= 1000) {
+        display_fps(counter);
+        // add a multiple of one second
+        Uint32 elapsed_slices = (now - counter->slice_start) / 1000;
+        counter->slice_start += 1000 * elapsed_slices;
+        counter->nr_rendered = 0;
+#ifdef SKIP_FRAMES
+        counter->nr_skipped = 0;
+#endif
+    }
+}
+
+void fps_counter_add_rendered_frame(struct fps_counter *counter) {
+    check_expired(counter);
+    ++counter->nr_rendered;
+}
+
+#ifdef SKIP_FRAMES
+void fps_counter_add_skipped_frame(struct fps_counter *counter) {
+    check_expired(counter);
+    ++counter->nr_skipped;
+}
+#endif

app/src/fpscounter.h

@@ -0,0 +1,26 @@
+#ifndef FPSCOUNTER_H
+#define FPSCOUNTER_H
+
+#include <SDL2/SDL_stdinc.h>
+
+#include "config.h"
+
+struct fps_counter {
+    SDL_bool started;
+    Uint32 slice_start; // initialized by SDL_GetTicks()
+    int nr_rendered;
+#ifdef SKIP_FRAMES
+    int nr_skipped;
+#endif
+};
+
+void fps_counter_init(struct fps_counter *counter);
+void fps_counter_start(struct fps_counter *counter);
+void fps_counter_stop(struct fps_counter *counter);
+
+void fps_counter_add_rendered_frame(struct fps_counter *counter);
+#ifdef SKIP_FRAMES
+void fps_counter_add_skipped_frame(struct fps_counter *counter);
+#endif
+
+#endif

app/src/frames.c

@@ -33,6 +33,7 @@ SDL_bool frames_init(struct frames *frames) {
     // there is initially no rendering frame, so consider it has already been
     // consumed
     frames->rendering_frame_consumed = SDL_TRUE;
+    fps_counter_init(&frames->fps_counter);
 
     return SDL_TRUE;
 
@@ -68,8 +69,8 @@ SDL_bool frames_offer_decoded_frame(struct frames *frames) {
         cond_wait(frames->rendering_frame_consumed_cond, frames->mutex);
     }
 #else
-    if (!frames->rendering_frame_consumed) {
-        LOGD("Skip frame");
+    if (frames->fps_counter.started && !frames->rendering_frame_consumed) {
+        fps_counter_add_skipped_frame(&frames->fps_counter);
     }
 #endif
 
@@ -85,6 +86,9 @@ SDL_bool frames_offer_decoded_frame(struct frames *frames) {
 const AVFrame *frames_consume_rendered_frame(struct frames *frames) {
     SDL_assert(!frames->rendering_frame_consumed);
     frames->rendering_frame_consumed = SDL_TRUE;
+    if (frames->fps_counter.started) {
+        fps_counter_add_rendered_frame(&frames->fps_counter);
+    }
 #ifndef SKIP_FRAMES
     // if SKIP_FRAMES is disabled, then notify the decoder the current frame is
     // consumed, so that it may push a new one

app/src/frames.h

@@ -5,6 +5,7 @@
 #include <SDL2/SDL_stdinc.h>
 
 #include "config.h"
+#include "fpscounter.h"
 
 // forward declarations
 typedef struct AVFrame AVFrame;
@@ -18,6 +19,7 @@ struct frames {
     SDL_cond *rendering_frame_consumed_cond;
 #endif
     SDL_bool rendering_frame_consumed;
+    struct fps_counter fps_counter;
 };
 
 SDL_bool frames_init(struct frames *frames);

app/src/scrcpy.c

@@ -15,6 +15,7 @@
 #include "device.h"
 #include "events.h"
 #include "frames.h"
+#include "fpscounter.h"
 #include "log.h"
 #include "lockutil.h"
 #include "netutil.h"
@@ -29,24 +30,6 @@ static struct frames frames;
 static struct decoder decoder;
 static struct controller controller;
 
-static long timestamp_ms(void) {
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    return tv.tv_sec * 1000 + tv.tv_usec / 1000;
-}
-
-static void count_frame(void) {
-    static long ts = 0;
-    static int nbframes = 0;
-    long now = timestamp_ms();
-    ++nbframes;
-    if (now - ts > 1000) {
-        LOGD("%d fps", nbframes);
-        ts = now;
-        nbframes = 0;
-    }
-}
-
 static void event_loop(void) {
     SDL_Event event;
     while (SDL_WaitEvent(&event)) {
@@ -62,11 +45,11 @@ static void event_loop(void) {
                     screen.has_frame = SDL_TRUE;
                     // this is the very first frame, show the window
                     screen_show_window(&screen);
+                    fps_counter_start(&frames.fps_counter);
                 }
                 if (!screen_update_frame(&screen, &frames)) {
                     return;
                 }
-                count_frame(); // display fps for debug
                 break;
             case SDL_WINDOWEVENT:
                 switch (event.window.event) {