[FFmpeg-cvslog] x11grab: fixed next frame capture time calculation

[Trevor \\ Higgins]

ffmpeg | branch: master | Trevor \\\\ Higgins <doublebackslash at gmail.com> | Wed Feb  3 09:10:01 2016 -0500| [6632802aa00c8fe2126697d9eb8e498c600aee79] | committer: Michael Niedermayer

x11grab: fixed next frame capture time calculation

The next frame time could slip, causing the frame rate to drop until
 frames were dropped. Now will capture at the next correct moment instead.

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6632802aa00c8fe2126697d9eb8e498c600aee79
---

 libavdevice/x11grab.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libavdevice/x11grab.c b/libavdevice/x11grab.c
index bdfaa66..9dc3472 100644
--- a/libavdevice/x11grab.c
+++ b/libavdevice/x11grab.c
@@ -526,16 +526,11 @@ static int x11grab_read_packet(AVFormatContext *s1, AVPacket *pkt)
     int64_t curtime, delay;
     struct timespec ts;
 
-    /* Calculate the time of the next frame */
-    s->time_frame += INT64_C(1000000);
-
     /* wait based on the frame rate */
     for (;;) {
         curtime = av_gettime();
         delay   = s->time_frame * av_q2d(s->time_base) - curtime;
         if (delay <= 0) {
-            if (delay < INT64_C(-1000000) * av_q2d(s->time_base))
-                s->time_frame += INT64_C(1000000);
             break;
         }
         ts.tv_sec  = delay / 1000000;
@@ -543,6 +538,11 @@ static int x11grab_read_packet(AVFormatContext *s1, AVPacket *pkt)
         nanosleep(&ts, NULL);
     }
 
+    /* Calculate the time of the next frame */
+    do {
+      s->time_frame += INT64_C(1000000);
+    } while ((s->time_frame * av_q2d(s->time_base) - curtime) <= 0);
+
     av_init_packet(pkt);
     pkt->data = image->data;
     pkt->size = s->frame_size;