tests: Use a predefined function for lavf-rm test

tests/lavf-regression.sh

@@ -15,7 +15,8 @@ do_lavf()
 {
     file=${outfile}lavf.$1
     do_avconv $file $DEC_OPTS -f image2 -c:v pgmyuv -i $raw_src $DEC_OPTS -ar 44100 -f s16le $2 -i $pcm_src $ENC_OPTS -b:a 64k -t 1 -qscale:v 10 $3
-    do_avconv_crc $file $DEC_OPTS -i $target_path/$file $4
+    test $5 = "disable_crc" ||
+        do_avconv_crc $file $DEC_OPTS -i $target_path/$file $4
 }
 
 do_streamed_images()
@@ -53,9 +54,8 @@ fi
 
 if [ -n "$do_rm" ] ; then
 file=${outfile}lavf.rm
-do_avconv $file $DEC_OPTS -f image2 -c:v pgmyuv -i $raw_src $DEC_OPTS -ar 44100 -f s16le -i $pcm_src $ENC_OPTS -t 1 -qscale 10 -c:a ac3_fixed -b:a 64k
-# broken
-#do_avconv_crc $file -i $target_path/$file
+# The RealMedia muxer is broken.
+do_lavf rm "" "-c:a ac3_fixed" "" disable_crc
 fi
 
 if [ -n "$do_mpg" ] ; then