video: move display and timing to a separate thread

The VO is run inside its own thread. It also does most of video timing.
The playloop hands the image data and a realtime timestamp to the VO,
and the VO does the rest.

In particular, this allows the playloop to do other things, instead of
blocking for video redraw. But if anything accesses the VO during video
timing, it will block.

This also fixes vo_sdl.c event handling; but that is only a side-effect,
since reimplementing the broken way would require more effort.

Also drop --softsleep. In theory, this option helps if the kernel's
sleeping mechanism is too inaccurate for video timing. In practice, I
haven't ever encountered a situation where it helps, and it just burns
CPU cycles. On the other hand it's probably actively harmful, because
it prevents the libavcodec decoder threads from doing real work.

Side note:

Originally, I intended that multiple frames can be queued to the VO. But
this is not done, due to problems with OSD and other certain features.
OSD in particular is simply designed in a way that it can be neither
timed nor copied, so you do have to render it into the video frame
before you can draw the next frame. (Subtitles have no such restriction.
sd_lavc was even updated to fix this.) It seems the right solution to
queuing multiple VO frames is rendering on VO-backed framebuffers, like
vo_vdpau.c does. This requires VO driver support, and is out of scope
of this commit.

As consequence, the VO has a queue size of 1. The existing video queue
is just needed to compute frame duration, and will be moved out in the
next commit.

1 files changed, 25 insertions, 87 deletions

diff --git a/player/video.c b/player/video.c
index 5b2748c894..1ee8ec1203 100644
--- a/player/video.c
+++ b/player/video.c
@@ -613,25 +613,6 @@ static int update_video(struct MPContext *mpctx, double endpts, bool reconfig_ok
     return VD_NEW_FRAME;
 }
 
-static double timing_sleep(struct MPContext *mpctx, double time_frame)
-{
-    // assume kernel HZ=100 for softsleep, works with larger HZ but with
-    // unnecessarily high CPU usage
-    struct MPOpts *opts = mpctx->opts;
-    double margin = opts->softsleep ? 0.011 : 0;
-    while (time_frame > margin) {
-        mp_sleep_us(1000000 * (time_frame - margin));
-        time_frame -= get_relative_time(mpctx);
-    }
-    if (opts->softsleep) {
-        if (time_frame < 0)
-            MP_WARN(mpctx, "Warning! Softsleep underflow!\n");
-        while (time_frame > 0)
-            time_frame -= get_relative_time(mpctx);  // burn the CPU
-    }
-    return time_frame;
-}
-
 static void update_avsync(struct MPContext *mpctx)
 {
     if (mpctx->audio_status != STATUS_PLAYING ||
@@ -673,7 +654,6 @@ static void adjust_sync(struct MPContext *mpctx, double frame_time)
     double v_pts = mpctx->video_next_pts;
     double av_delay = a_pts - v_pts;
     // Try to sync vo_flip() so it will *finish* at given time
-    av_delay += mpctx->last_vo_flip_duration;
     av_delay += mpctx->audio_delay;   // This much pts difference is desired
 
     double change = av_delay * 0.1;
@@ -772,7 +752,6 @@ void write_video(struct MPContext *mpctx, double endpts)
         return;
 
     mpctx->time_frame -= get_relative_time(mpctx);
-    double audio_pts = playing_audio_pts(mpctx);
     if (!mpctx->sync_audio_to_video || mpctx->video_status < STATUS_READY) {
         mpctx->time_frame = 0;
     } else if (mpctx->audio_status == STATUS_PLAYING &&
@@ -806,24 +785,32 @@ void write_video(struct MPContext *mpctx, double endpts)
          * If untimed is set always output frames immediately
          * without sleeping.
          */
-        if (mpctx->time_frame < -0.2 || opts->untimed || vo->untimed)
+        if (mpctx->time_frame < -0.2 || opts->untimed || vo->driver->untimed)
             mpctx->time_frame = 0;
     }
 
-    double vsleep = mpctx->time_frame - vo->flip_queue_offset;
-    if (vsleep > 0.050) {
-        mpctx->sleeptime = MPMIN(mpctx->sleeptime, vsleep - 0.040);
-        return;
-    }
-    mpctx->sleeptime = 0;
-    mpctx->playing_last_frame = false;
-
     // last frame case
+    // TODO: should be _after_ wait
+    mpctx->playing_last_frame = false;
     if (r != VD_NEW_FRAME)
         return;
 
-    //=================== FLIP PAGE (VIDEO BLT): ======================
+    double time_frame = MPMAX(mpctx->time_frame, -1);
+    int64_t pts = mp_time_us() + (int64_t)(time_frame * 1e6);
 
+    if (!vo_is_ready_for_frame(vo, pts))
+        return; // wait until VO wakes us up to get more frames
+
+    int64_t duration = -1;
+    double vpts0 = vo_get_next_pts(vo, 0);
+    double vpts1 = vo_get_next_pts(vo, 1);
+    if (vpts0 != MP_NOPTS_VALUE && vpts1 != MP_NOPTS_VALUE) {
+        // expected A/V sync correction is ignored
+        double diff = (vpts1 - vpts0) / opts->playback_speed;
+        if (mpctx->time_frame < 0)
+            diff += mpctx->time_frame;
+        duration = MPCLAMP(diff, 0, 10) * 1e6;
+    }
 
     mpctx->video_pts = mpctx->video_next_pts;
     mpctx->last_vo_pts = mpctx->video_pts;
@@ -832,66 +819,17 @@ void write_video(struct MPContext *mpctx, double endpts)
     update_subtitles(mpctx);
     update_osd_msg(mpctx);
 
-    MP_STATS(mpctx, "vo draw frame");
-
-    vo_new_frame_imminent(vo);
-
-    MP_STATS(mpctx, "vo sleep");
+    vo_queue_frame(vo, pts, duration);
 
+    // For print_status - VO call finishing early is OK for sync
     mpctx->time_frame -= get_relative_time(mpctx);
-    mpctx->time_frame -= vo->flip_queue_offset;
-    if (mpctx->time_frame > 0.001)
-        mpctx->time_frame = timing_sleep(mpctx, mpctx->time_frame);
-    mpctx->time_frame += vo->flip_queue_offset;
-
-    int64_t t2 = mp_time_us();
-    /* Playing with playback speed it's possible to get pathological
-     * cases with mpctx->time_frame negative enough to cause an
-     * overflow in pts_us calculation, thus the MPMAX. */
-    double time_frame = MPMAX(mpctx->time_frame, -1);
-    int64_t pts_us = mpctx->last_time + time_frame * 1e6;
-    int duration = -1;
-    double pts2 = vo_get_next_pts(vo, 0); // this is the next frame PTS
-    if (mpctx->video_pts != MP_NOPTS_VALUE && pts2 == MP_NOPTS_VALUE) {
-        // Make up a frame duration. Using the frame rate is not a good
-        // choice, since the frame rate could be unset/broken/random.
-        float fps = mpctx->d_video->fps;
-        double frame_duration = fps > 0 ? 1.0 / fps : 0;
-        pts2 = mpctx->video_pts + MPCLAMP(frame_duration, 0.0, 5.0);
-    }
-    if (pts2 != MP_NOPTS_VALUE) {
-        // expected A/V sync correction is ignored
-        double diff = (pts2 - mpctx->video_pts);
-        diff /= opts->playback_speed;
-        if (mpctx->time_frame < 0)
-            diff += mpctx->time_frame;
-        if (diff < 0)
-            diff = 0;
-        if (diff > 10)
-            diff = 10;
-        duration = diff * 1e6;
-        mpctx->last_frame_duration = diff;
-    }
-    if (mpctx->video_status != STATUS_PLAYING)
-        duration = -1;
-
-    MP_STATS(mpctx, "start flip");
-    vo_flip_page(vo, pts_us | 1, duration);
-    MP_STATS(mpctx, "end flip");
-
-    if (audio_pts != MP_NOPTS_VALUE)
-        MP_STATS(mpctx, "value %f ptsdiff", mpctx->video_pts - audio_pts);
-
-    mpctx->last_vo_flip_duration = (mp_time_us() - t2) * 0.000001;
-    if (vo->driver->flip_page_timed) {
-        // No need to adjust sync based on flip speed
-        mpctx->last_vo_flip_duration = 0;
-        // For print_status - VO call finishing early is OK for sync
-        mpctx->time_frame -= get_relative_time(mpctx);
-    }
+
     mpctx->shown_vframes++;
-    if (mpctx->video_status < STATUS_PLAYING)
+    if (mpctx->video_status < STATUS_PLAYING) {
         mpctx->video_status = STATUS_READY;
+        // After a seek, make sure to wait until the first frame is visible.
+        vo_wait_frame(vo);
+    }
     update_avsync(mpctx);
     screenshot_flip(mpctx);