mmal/deinterlace: Do not filter the same picture twice

If the same picture, containing the same buffer header without being
re-acquired in the meantime, is sent to image_fx twice it will portentially
cause a double free within the mmal core as it destroys the internal
refcounting. Use the same guarding mechanism which is already in place in
mmal/vout to ensure this is not happening at any point.
Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/hw/mmal/deinterlace.c

@@ -337,16 +337,22 @@ static picture_t *deinterlace(filter_t *filter, picture_t *picture)
     buffer->pts = picture->date;
     buffer->cmd = 0;
 
+    if (!picture->p_sys->displayed) {
         vlc_mutex_lock(&sys->buffer_cond_mutex);
         status = mmal_port_send_buffer(sys->input, buffer);
         if (status != MMAL_SUCCESS) {
             msg_Err(filter, "Failed to send buffer to input port (status=%"PRIx32" %s)",
                     status, mmal_status_to_string(status));
+            picture_Release(picture);
         } else {
+            picture->p_sys->displayed = true;
             atomic_fetch_add(&sys->input_in_transit, 1);
             vlc_cond_signal(&sys->buffer_cond);
         }
         vlc_mutex_unlock(&sys->buffer_cond_mutex);
+    } else {
+        picture_Release(picture);
+    }
 
     /*
      * Send output buffers