video(1): measure with mono clock (tester wanted)

[Scott Cheloha]

So that your stats stay correct if the system clock is changed.

This is simple enough to suggest that it's correct at a glance,
but I have no hardware to test this with.  Can anyone confirm that
this works?

--
Scott Cheloha

Index: app/video/video.c
===================================================================
RCS file: /cvs/xenocara/app/video/video.c,v
retrieving revision 1.23
diff -u -p -r1.23 video.c
--- app/video/video.c   26 Nov 2016 11:49:15 -0000      1.23
+++ app/video/video.c   6 Apr 2018 14:21:26 -0000
@@ -30,6 +30,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <unistd.h>
 
 #include <X11/Xlib.h>
@@ -1635,7 +1636,7 @@ int
 stream(struct video *vid)
 {
        struct xdsp *x = &vid->xdsp;
-       struct timeval tp_start, tp_now, tp_run;
+       struct timespec tp_start, tp_now, tp_run;
        struct itimerval frit;
        double run_time;
        uint8_t *src;
@@ -1643,7 +1644,7 @@ stream(struct video *vid)
        int sequence = 20, ret, err, todo, done;
 
        /* Guard against uninitialized variable in case no frame is grabbed. */
-       gettimeofday(&tp_start, NULL);
+       clock_gettime(CLOCK_MONOTONIC, &tp_start);
 
        if (vid->fps && !vid->nofps) {
                fus = 1000000 / vid->fps;
@@ -1759,21 +1760,21 @@ stream(struct video *vid)
                        frames_played++;
 
                if (frames_played == 0)
-                       gettimeofday(&tp_start, NULL);
+                       clock_gettime(CLOCK_MONOTONIC, &tp_start);
 
                if (vid->verbose > 1 && frames_played > 0 &&
                    (frames_played) % sequence == 0) {
-                       gettimeofday(&tp_now, NULL);
-                       timersub(&tp_now, &tp_start, &tp_run);
+                       clock_gettime(CLOCK_MONOTONIC, &tp_now);
+                       timespecsub(&tp_now, &tp_start, &tp_run);
                        run_time = tp_run.tv_sec +
-                           (double)tp_run.tv_usec / 1000000;
+                           tp_run.tv_nsec / 1000000000.0;
                        fprintf(stderr, "frames: %08ld, seconds: "
                            "%09.2f, fps: %08.5f\r", frames_played,
                            run_time, ((double)frames_played) / run_time);
                        fflush(stderr);
                }
        }
-       gettimeofday(&tp_now, NULL);
+       clock_gettime(CLOCK_MONOTONIC, &tp_now);
 
        if (vid->fps) {
                timerclear(&frit.it_value);
@@ -1793,8 +1794,8 @@ stream(struct video *vid)
                fprintf(stderr, "\n");
 
        if (vid->verbose > 0) {
-               timersub(&tp_now, &tp_start, &tp_run);
-               run_time = tp_run.tv_sec + (double)tp_run.tv_usec / 1000000;
+               timespecsub(&tp_now, &tp_start, &tp_run);
+               run_time = tp_run.tv_sec + tp_run.tv_nsec / 1000000000.0;
                fprintf(stderr, "run time: %f seconds\n", run_time);
                fprintf(stderr, "frames grabbed: %ld\n", frames_grabbed);
                fprintf(stderr, "frames played: %ld\n", frames_played + 1);