FATE: add a test for the volume filter

tests/fate/filter.mak

@@ -78,6 +78,13 @@ fate-filter-transpose: CMD = framecrc -c:v pgmyuv -i $(SRC) -vf transpose
 FATE_FILTER_VSYNTH-$(CONFIG_UNSHARP_FILTER) += fate-filter-unsharp
 fate-filter-unsharp: CMD = framecrc -c:v pgmyuv -i $(SRC) -vf unsharp
 
+FATE_FILTER-$(call FILTERDEMDECENCMUX, VOLUME, WAV, PCM_S16LE, PCM_S16LE, PCM_S16LE) += fate-filter-volume
+fate-filter-volume: SRC = $(TARGET_PATH)/tests/data/asynth-44100-2.wav
+fate-filter-volume: tests/data/asynth-44100-2.wav
+fate-filter-volume: CMD = md5 -i $(SRC) -af volume=precision=fixed:volume=0.5 -f s16le
+fate-filter-volume: CMP = oneline
+fate-filter-volume: REF = 4d6ba75ef3e32d305d066b9bc771d6f4
+
 FATE_YADIF += fate-filter-yadif-mode0
 fate-filter-yadif-mode0: CMD = framecrc -flags bitexact -idct simple -i $(SAMPLES)/mpeg2/mpeg2_field_encoding.ts -vf yadif=0