vo_gpu_next: add validation for invalid pl_queue usage

This is mainly for debugging purposes, as it should't happen in normal
use. If it does, it needs fixing.

1 files changed, 22 insertions, 1 deletions

diff --git a/video/out/vo_gpu_next.c b/video/out/vo_gpu_next.c
index 869a11d54d..f079d7570e 100644
--- a/video/out/vo_gpu_next.c
+++ b/video/out/vo_gpu_next.c
@@ -874,6 +874,7 @@ static void draw_frame(struct vo *vo, struct vo_frame *frame)
     bool cache_frame = will_redraw || frame->still;
     bool can_interpolate = opts->interpolation && frame->display_synced &&
                            !frame->still && frame->num_frames > 1;
+    double pts_offset = can_interpolate ? frame->ideal_frame_vsync : 0;
     params.info_callback = info_callback;
     params.info_priv = vo;
     params.skip_caching_single_frame = !cache_frame;
@@ -881,6 +882,27 @@ static void draw_frame(struct vo *vo, struct vo_frame *frame)
     if (frame->still)
         params.frame_mixer = NULL;
 
+    // pl_queue advances its internal virtual PTS and culls available frames
+    // based on this value and the VPS/FPS ratio. Requesting a non-monotonic PTS
+    // is an invalid use of pl_queue. Reset it if this happens in an attempt to
+    // recover as much as possible. Ideally, this should never occur, and if it
+    // does, it should be corrected. The ideal_frame_vsync may be negative if
+    // the last draw did not align perfectly with the vsync. In this case, we
+    // should have the previous frame available in pl_queue, or a reset is
+    // already requested. Clamp the check to 0, as we don't have the previous
+    // frame in vo_frame anyway.
+    struct pl_source_frame vpts;
+    if (frame->current && !p->want_reset) {
+        if (pl_queue_peek(p->queue, 0, &vpts) &&
+            frame->current->pts + MPMAX(0, pts_offset) < vpts.pts)
+        {
+            MP_VERBOSE(vo, "Forcing queue refill, PTS(%f + %f | %f) < VPTS(%f)\n",
+                       frame->current->pts, pts_offset,
+                       frame->ideal_frame_vsync_duration, vpts.pts);
+            p->want_reset = true;
+        }
+    }
+
     // Push all incoming frames into the frame queue
     for (int n = 0; n < frame->num_frames; n++) {
         int id = frame->frame_id + n;
@@ -929,7 +951,6 @@ static void draw_frame(struct vo *vo, struct vo_frame *frame)
 
     struct pl_swapchain_frame swframe;
     struct ra_swapchain *sw = p->ra_ctx->swapchain;
-    double pts_offset = can_interpolate ? frame->ideal_frame_vsync : 0;
     bool should_draw = sw->fns->start_frame(sw, NULL); // for wayland logic
     if (!should_draw || !pl_swapchain_start_frame(p->sw, &swframe)) {
         if (frame->current) {