gradfun: add notice from the MPlayer manual

Add notice telling that the filter is designed for playback only.

1 files changed, 4 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 21aa7b5d7a..80f6fb0a9b 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -585,6 +585,10 @@ regions by truncation to 8bit colordepth.
 Interpolate the gradients that should go where the bands are, and
 dither them.
 
+This filter is designed for playback only.  Do not use it prior to
+lossy compression, because compression tends to lose the dither and
+bring back the bands.
+
 The filter takes two optional parameters, separated by ':':
 @var{strength}:@var{radius}