Improve grammar and readability

Patch by Rodney Baker, rodney dot baker at iinet dot net dot au

Originally committed as revision 23499 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -1347,15 +1347,15 @@ typedef struct AVCodecContext {
      * - encoding: Set by user.
      * - decoding: Set by user.
      * Setting this to STRICT or higher means the encoder and decoder will
-     * generally do stupid things. While setting it to inofficial or lower
-     * will mean the encoder might use things that are not supported by all
-     * spec compliant decoders. Decoders make no difference between normal,
-     * inofficial and experimental, that is they always try to decode things
-     * when they can unless they are explicitly asked to behave stupid
+     * generally do stupid things, whereas setting it to inofficial or lower
+     * will mean the encoder might produce output that is not supported by all
+     * spec-compliant decoders. Decoders don't differentiate between normal,
+     * inofficial and experimental (that is, they always try to decode things
+     * when they can) unless they are explicitly asked to behave stupidly
      * (=strictly conform to the specs)
      */
     int strict_std_compliance;
-#define FF_COMPLIANCE_VERY_STRICT   2 ///< Strictly conform to a older more strict version of the spec or reference software.
+#define FF_COMPLIANCE_VERY_STRICT   2 ///< Strictly conform to an older more strict version of the spec or reference software.
 #define FF_COMPLIANCE_STRICT        1 ///< Strictly conform to all the things in the spec no matter what consequences.
 #define FF_COMPLIANCE_NORMAL        0
 #define FF_COMPLIANCE_INOFFICIAL   -1 ///< Allow inofficial extensions.