doc: fix spelling errors

Reviewed-by: Lou Logan <lou@lrcd.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

doc/filters.texi

@@ -9665,7 +9665,7 @@ Scene change detection method. Scene change leads motion vectors to be in random
 @item none
 Disable scene change detection.
 @item fdiff
-Frame difference. Corresponding pixel values are compared and if it statisfies @var{scd_threshold} scene change is detected.
+Frame difference. Corresponding pixel values are compared and if it satisfies @var{scd_threshold} scene change is detected.
 @end table
 Default method is @samp{fdiff}.
 

doc/formats.texi

@@ -63,7 +63,7 @@ This ensures that file and data checksums are reproducible and match between
 platforms. Its primary use is for regression testing.
 @item shortest
 Stop muxing at the end of the shortest stream.
-It may be needed to increase max_interleave_delta to avoid flusing the longer
+It may be needed to increase max_interleave_delta to avoid flushing the longer
 streams before EOF.
 @end table
 

libavcodec/4xm.c

@@ -532,7 +532,7 @@ static int decode_i_block(FourXContext *f, int16_t *block)
             }
             i    += code >> 4;
             if (i >= 64) {
-                av_log(f->avctx, AV_LOG_ERROR, "run %d oveflow\n", i);
+                av_log(f->avctx, AV_LOG_ERROR, "run %d overflow\n", i);
                 return 0;
             }