flashsv: replace bitstream description by a link to the specification

An official specification now exists and it is both more detailed and easier to
understand than the incomplete notes available here.  Also remove ideas on how
to implement an encoder; these notes are already present in the encoder.

libavcodec/flashsv.c

@@ -25,26 +25,10 @@
  * Flash Screen Video decoder
  * @author Alex Beregszaszi
  * @author Benjamin Larsson
- */
-
-/* Bitstream description
- * The picture is divided into blocks that are zlib compressed.
- *
- * The decoder is fed complete frames, the frameheader contains:
- * 4bits of block width
- * 12bits of frame width
- * 4bits of block height
- * 12bits of frame height
- *
- * Directly after the header are the compressed blocks. The blocks
- * have their compressed size represented with 16bits in the beginnig.
- * If the size = 0 then the block is unchanged from the previous frame.
- * All blocks are decompressed until the buffer is consumed.
  *
- * Encoding ideas, a basic encoder would just use a fixed block size.
- * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
- * have to be quadratic. A brute force search with a set of diffrent
- * block sizes should give a better result then to just use a fixed size.
+ * A description of the bitstream format for Flash Screen Video version 1/2
+ * is part of the SWF File Format Specification (version 10), which can be
+ * downloaded from http://www.adobe.com/devnet/swf.html.
  */
 
 #include <stdio.h>