Clarify sample_aspect_ratio.

Originally committed as revision 15180 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 4c44376..18bde8e 100644 (file)
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1448,6 +1448,7 @@ typedef struct AVCodecContext {
 
     /**
      * sample aspect ratio (0 if unknown)
+     * That is the width of a pixel divided by the height of the pixel.
      * Numerator and denominator must be relatively prime and smaller than 256 for some video standards.
      * - encoding: Set by user.
      * - decoding: Set by libavcodec.