Originally committed as revision 17277 to svn://svn.ffmpeg.org/ffmpeg/trunk
* decoder to draw a horizontal band. It improves cache usage. Not
* all codecs can do that. You must check the codec capabilities
* beforehand.
+ * It is also used by hardware acceleration APIs as a callback
+ * to pass specific (partially decoded) data to the calling
+ * application so it could be passed to the rendering hardware.
* - encoding: unused
* - decoding: Set by user.
* @param height the height of the slice