FATE: use absolute difference from a target value in do_tiny_psnr()

This will allow comparison to original pre-encoded content instead of
comparing to expected decoded output.

tests/Makefile

@@ -116,7 +116,7 @@ fate: $(FATE)
 
 $(FATE): avconv$(EXESUF) $(FATE_UTILS:%=tests/%$(HOSTEXESUF))
 	@echo "TEST    $(@:fate-%=%)"
-	$(Q)$(SRC_PATH)/tests/fate-run.sh $@ "$(SAMPLES)" "$(TARGET_EXEC)" "$(TARGET_PATH)" '$(CMD)' '$(CMP)' '$(REF)' '$(FUZZ)' '$(THREADS)' '$(THREAD_TYPE)' '$(CPUFLAGS)' '$(CMP_SHIFT)'
+	$(Q)$(SRC_PATH)/tests/fate-run.sh $@ "$(SAMPLES)" "$(TARGET_EXEC)" "$(TARGET_PATH)" '$(CMD)' '$(CMP)' '$(REF)' '$(FUZZ)' '$(THREADS)' '$(THREAD_TYPE)' '$(CPUFLAGS)' '$(CMP_SHIFT)' '$(CMP_TARGET)'
 
 fate-list:
 	@printf '%s\n' $(sort $(FATE))

tests/fate-run.sh

@@ -19,6 +19,7 @@ threads=${9:-1}
 thread_type=${10:-frame+slice}
 cpuflags=${11:-all}
 cmp_shift=${12:-0}
+cmp_target=${13:-0}
 
 outdir="tests/data/fate"
 outfile="${outdir}/${test}"
@@ -26,24 +27,31 @@ errfile="${outdir}/${test}.err"
 cmpfile="${outdir}/${test}.diff"
 repfile="${outdir}/${test}.rep"
 
+# $1=value1, $2=value2, $3=threshold
+# prints 0 if absolute difference between value1 and value2 is <= threshold
+compare(){
+    v=$(echo "scale=2; if ($1 >= $2) { $1 - $2 } else { $2 - $1 }" | bc)
+    echo "if ($v <= $3) { 0 } else { 1 }" | bc
+}
+
 do_tiny_psnr(){
     psnr=$(tests/tiny_psnr "$1" "$2" 2 $cmp_shift 0)
     val=$(expr "$psnr" : ".*$3: *\([0-9.]*\)")
     size1=$(expr "$psnr" : '.*bytes: *\([0-9]*\)')
     size2=$(expr "$psnr" : '.*bytes:[ 0-9]*/ *\([0-9]*\)')
-    res=$(echo "if ($val $4 $fuzz) 1" | bc)
-    if [ "$res" != 1 ] || [ $size1 != $size2 ]; then
+    val_cmp=$(compare $val $cmp_target $fuzz)
+    if [ "$val_cmp" != 0 ] || [ $size1 != $size2 ]; then
         echo "$psnr"
         return 1
     fi
 }
 
 oneoff(){
-    do_tiny_psnr "$1" "$2" MAXDIFF '<='
+    do_tiny_psnr "$1" "$2" MAXDIFF
 }
 
 stddev(){
-    do_tiny_psnr "$1" "$2" stddev  '<='
+    do_tiny_psnr "$1" "$2" stddev
 }
 
 run(){