Computer-readable media storing computer-executable instructions for causing a node of a system configured for videoconferencing or other real-time communication, when programmed thereby, to perform bitstream modification operations comprising: receiving, at the node of the system, an incoming bitstream of encoded video organized according to a given codec standard or format; and outputting, from the node of the system, an outgoing bitstream; wherein the bitstream modification operations comprise, at the node of the system, processing the incoming bitstream to produce the outgoing bitstream of encoded video organized according to the given codec standard or format; wherein the incoming bitstream has multiple temporal layers (1310, 1320, 1410, 1420) and the outgoing bitstream has a single temporal layer; wherein the processing includes changing at least one syntax element between the incoming bitstream and the outgoing bitstream such that information about reference picture handling is changed; wherein the multiple temporal layers comprise a temporal base layer (1310, 1410) and at least one temporal enhancement layer (1320, 1420), wherein the temporal layers exhibit a regular pattern of reference picture dependencies, and none of the pictures in one of the temporal enhancement layers is initially marked as a reference picture; and wherein the processing to change the at least one syntax element comprises: for a picture in a temporal enhancement layer that is not already marked as a reference picture, marking the picture as a reference picture and adding a syntax structure that includes information about reference picture handling, and adding reference pictures from the multiple temporal layers into the single temporal layer so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions. receiving, at the node of the system, an incoming bitstream of encoded video organized according to a given codec standard or format; and outputting, from the node of the system, an outgoing bitstream; wherein the bitstream modification operations comprise, at the node of the system, processing the incoming bitstream to produce the outgoing bitstream of encoded video organized according to the given codec standard or format; wherein the incoming bitstream has multiple temporal layers (1310, 1320, 1410, 1420) and the outgoing bitstream has a single temporal layer; wherein the processing includes changing at least one syntax element between the incoming bitstream and the outgoing bitstream such that information about reference picture handling is changed; wherein the multiple temporal layers comprise a temporal base layer (1310, 1410) and at least one temporal enhancement layer (1320, 1420), wherein the temporal layers exhibit a regular pattern of reference picture dependencies, and none of the pictures in one of the temporal enhancement layers is initially marked as a reference picture; and wherein the processing to change the at least one syntax element comprises: for a picture in a temporal enhancement layer that is not already marked as a reference picture, marking the picture as a reference picture and adding a syntax structure that includes information about reference picture handling, and adding reference pictures from the multiple temporal layers into the single temporal layer so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions.