From 34bead485987b416685e73ca918610fff75d618d Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Wed, 27 Jan 2016 21:07:17 +0100
Subject: vo_opengl: replace tscale-interpolates-only with
 interpolation-threshold

The previous approach was too naive, and can e.g. ruin playback if
scheduling switches e.g. between 1 and 2 vsync per frame.
---
 video/out/opengl/video.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

(limited to 'video/out/opengl/video.c')

diff --git a/video/out/opengl/video.c b/video/out/opengl/video.c
index bbf01f2cbb..6945c82f9a 100644
--- a/video/out/opengl/video.c
+++ b/video/out/opengl/video.c
@@ -354,8 +354,8 @@ const struct gl_video_opts gl_video_opts_def = {
          .clamp = 1, }, // tscale
     },
     .scaler_resizes_only = 1,
-    .tscale_interpolates_only = 1,
     .scaler_lut_size = 6,
+    .interpolation_threshold = 0.0001,
     .alpha_mode = 3,
     .background = {0, 0, 0, 255},
     .gamma = 1.0f,
@@ -380,8 +380,8 @@ const struct gl_video_opts gl_video_opts_hq_def = {
          .clamp = 1, }, // tscale
     },
     .scaler_resizes_only = 1,
-    .tscale_interpolates_only = 1,
     .scaler_lut_size = 6,
+    .interpolation_threshold = 0.0001,
     .alpha_mode = 3,
     .background = {0, 0, 0, 255},
     .gamma = 1.0f,
@@ -424,7 +424,6 @@ const struct m_sub_options gl_video_conf = {
         SCALER_OPTS("tscale", 3),
         OPT_INTRANGE("scaler-lut-size", scaler_lut_size, 0, 4, 10),
         OPT_FLAG("scaler-resizes-only", scaler_resizes_only, 0),
-        OPT_FLAG("tscale-interpolates-only", tscale_interpolates_only, 0),
         OPT_FLAG("linear-scaling", linear_scaling, 0),
         OPT_FLAG("correct-downscaling", correct_downscaling, 0),
         OPT_FLAG("sigmoid-upscaling", sigmoid_upscaling, 0),
@@ -460,6 +459,7 @@ const struct m_sub_options gl_video_conf = {
         OPT_FLAG("rectangle-textures", use_rectangle, 0),
         OPT_COLOR("background", background, 0),
         OPT_FLAG("interpolation", interpolation, 0),
+        OPT_FLOAT("interpolation-threshold", interpolation_threshold, 0),
         OPT_CHOICE("blend-subtitles", blend_subs, 0,
                    ({"no", 0},
                     {"yes", 1},
@@ -2260,12 +2260,15 @@ void gl_video_render_frame(struct gl_video *p, struct vo_frame *frame, int fbo)
     if (has_frame) {
         gl_sc_set_vao(p->sc, &p->vao);
 
-        bool same_rate = !(frame->repeat || frame->num_vsyncs > 1);
+        bool interpolate = p->opts.interpolation && frame->display_synced &&
+                           (p->frames_drawn || !frame->still);
+        if (interpolate) {
+            double ratio = frame->ideal_frame_duration / frame->vsync_interval;
+            if (fabs(ratio - 1.0) < p->opts.interpolation_threshold)
+                interpolate = false;
+        }
 
-        if (p->opts.interpolation && frame->display_synced &&
-            (p->frames_drawn || !frame->still) &&
-            (!same_rate || !p->opts.tscale_interpolates_only))
-        {
+        if (interpolate) {
             gl_video_interpolate_frame(p, frame, fbo);
         } else {
             bool is_new = !frame->redraw && !frame->repeat;
-- 
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