I'm actually seeing this myself from time to time. When I think about it, this might be a problem caused by the constant autofocusing, although I remember having seen this some time ago as well. Maybe we should wait until the previous image has been decoded before calling autofocus again, just to make sure it does not get called again and again when the autofocus is temporarily causing the image to be out of focus?

Or would it be better to wait for the autofocus' success signal before calling the decoders at all? A simple way would be to set a "bool readyForDecode" to true whenever the autofocus callback returns with success and to false whenever autofocus is initiated?