A multiplexer selectively chooses packets for discarding during periods of congestion. In a first embodiment, thresholds for fill levels of a FIFO queue are set for a plurality of priority types. As thresholds are exceeded, incoming packet below a set priority level will be prevented from entering the queue and packets at the front of the queue below the set priority will be discarded. In a second embodiment, packets within a queue may be marked for deletion. A forward/discard list assigns an index to a new packet and maintains a list of the stream associated with each packet. A priority index list maintains a list of packets for each priority type by index number. A video metadata buffer stores the metadata for each enqueued packet. A physical video buffer stores the packets. When an incoming packet cannot be enqueued, packets of lower priority are detected by reference to the index list and marked for discard.