mfplat: Fix MFGetPlaneSize() behavior for invalid formats.

dlls/mfplat/mediatype.c

@@ -2755,10 +2755,10 @@ HRESULT WINAPI MFGetPlaneSize(DWORD fourcc, DWORD width, DWORD height, DWORD *si
     memcpy(&subtype, &MFVideoFormat_Base, sizeof(subtype));
     subtype.Data1 = fourcc;
 
-    if (!(format = mf_get_video_format(&subtype)))
-        return MF_E_INVALIDMEDIATYPE;
-
-    stride = mf_get_stride_for_format(format, width);
+    if ((format = mf_get_video_format(&subtype)))
+        stride = mf_get_stride_for_format(format, width);
+    else
+        stride = 0;
 
     switch (fourcc)
     {

dlls/mfplat/tests/mfplat.c

@@ -4254,6 +4254,11 @@ static void test_MFGetPlaneSize(void)
         return;
     }
 
+    size = 1;
+    hr = pMFGetPlaneSize(0xdeadbeef, 64, 64, &size);
+    ok(hr == S_OK, "Unexpected hr %#x.\n", hr);
+    ok(size == 0, "Unexpected size %u.\n", size);
+
     for (i = 0; i < ARRAY_SIZE(image_size_tests); ++i)
     {
         const struct image_size_test *ptr = &image_size_tests[i];