man: expand on the smoothmotion documentation

Hopefully this will clear up how the thing is supposed to work (and that it's
not SVP, nor MVTools).

1 files changed, 13 insertions, 4 deletions

diff --git a/DOCS/man/vo.rst b/DOCS/man/vo.rst
index 8133e0cb56..99229fa544 100644
--- a/DOCS/man/vo.rst
+++ b/DOCS/man/vo.rst
@@ -580,10 +580,19 @@ Available video output drivers are:
 
     ``smoothmotion``
         Use frame interpolation to reduce stuttering caused by mismatches in
-        video fps and display refresh rate (similar to MadVR's smoothmotion,
-        thus the naming). GPU drivers or compositing window managers overriding
-        vsync behavior can lead to bad results. If the framerate is close to or
-        over the display refresh rate, results can be bad as well.
+        video fps and display refresh rate.
+
+        Instead of drawing each frame exactly once, smoothmotion redraws the
+        the OpenGL scene at the display refresh rate. If a vsync is detected
+        to be the one when a frame changes to the next, a linear interpolation
+        of the previous frame with next is shown instead.
+
+        This means that displaying a 1fps video on a 60hz monitor will blend
+        at most during 1 vsync for each second of playback.
+
+        GPU drivers or compositing window managers overriding vsync behavior
+        can lead to bad results. If the framerate is close to or over the
+        display refresh rate, results can be bad as well.
 
         .. note:: On systems other than Linux, you currently must set the
                   ``--display-fps`` option, or the results will be bad.