Update ff_rv34_decode_frame() arguments definition

Originally committed as revision 15980 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/rv34.c

@@ -1351,7 +1351,7 @@ static int get_slice_offset(AVCodecContext *avctx, uint8_t *buf, int n)
 
 int ff_rv34_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size,
-                            uint8_t *buf, int buf_size)
+                            const uint8_t *buf, int buf_size)
 {
     RV34DecContext *r = avctx->priv_data;
     MpegEncContext *s = &r->s;

libavcodec/rv34.h

@@ -123,7 +123,7 @@ typedef struct RV34DecContext{
  */
 int ff_rv34_get_start_offset(GetBitContext *gb, int blocks);
 int ff_rv34_decode_init(AVCodecContext *avctx);
-int ff_rv34_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size);
+int ff_rv34_decode_frame(AVCodecContext *avctx, void *data, int *data_size, const uint8_t *buf, int buf_size);
 int ff_rv34_decode_end(AVCodecContext *avctx);
 
 #endif /* AVCODEC_RV34_H */