evr/mixer: Drop input samples on flush.

dlls/evr/mixer.c

@@ -949,6 +949,7 @@ static HRESULT WINAPI video_mixer_transform_ProcessMessage(IMFTransform *iface,
 {
     struct video_mixer *mixer = impl_from_IMFTransform(iface);
     HRESULT hr = S_OK;
+    unsigned int i;
 
     TRACE("%p, %u, %#lx.\n", iface, message, param);
 
@@ -966,6 +967,23 @@ static HRESULT WINAPI video_mixer_transform_ProcessMessage(IMFTransform *iface,
 
             break;
 
+        case MFT_MESSAGE_COMMAND_FLUSH:
+
+            EnterCriticalSection(&mixer->cs);
+
+            for (i = 0; i < mixer->input_count; ++i)
+            {
+                if (mixer->inputs[i].sample)
+                {
+                    IMFSample_Release(mixer->inputs[i].sample);
+                    mixer->inputs[i].sample = NULL;
+                }
+            }
+
+            LeaveCriticalSection(&mixer->cs);
+
+            break;
+
         case MFT_MESSAGE_COMMAND_DRAIN:
             break;