shithub: libvpx

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Merge "Fix kf detection in some slide shows."

--- a/vp9/encoder/vp9_firstpass.c

+++ b/vp9/encoder/vp9_firstpass.c

@@ -2700,6 +2700,15 @@

 #endif

 }

+// Slide show transition detection.

+// Tests for case where there is very low error either side of the current frame

+// but much higher just for this frame. This can help detect key frames in

+// slide shows even where the slides are pictures of different sizes.

+// It will not help if the transition is a fade or other multi-frame effect.

+static int slide_transition(double this_err, double last_err, double next_err) {

+  return (this_err > (last_err * 5.0)) && (this_err > (next_err * 5.0));

+}

+

 // Threshold for use of the lagging second reference frame. High second ref

 // usage may point to a transient event like a flash or occlusion rather than

 // a real scene cut.

@@ -2744,6 +2753,8 @@

   if ((this_frame->pcnt_second_ref < SECOND_REF_USEAGE_THRESH) &&

       (next_frame->pcnt_second_ref < SECOND_REF_USEAGE_THRESH) &&

       ((this_frame->pcnt_inter < VERY_LOW_INTER_THRESH) ||

+       (slide_transition(this_frame->coded_error, last_frame->coded_error,

+                         next_frame->coded_error)) ||

        ((pcnt_intra > MIN_INTRA_LEVEL) &&

         (pcnt_intra > (INTRA_VS_INTER_THRESH * modified_pcnt_inter)) &&

         ((this_frame->intra_error /