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, the outgoing bitstream being transmitted to a receiver node of the system, 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, including changing at least one syntax element between the incoming bitstream and the outgoing bitstream such that information about reference picture handling is changed so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions; and the processing of the incoming bitstream to change the at least one syntax element includes switching between multiple modes, the multiple modes including: a first mode in which instantaneous decoding refresh, IDR, pictures in the incoming bitstream are maintained in the outgoing bitstream; and a second mode in which IDR pictures in the incoming bitstream are converted to intra, I, pictures in the outgoing bitstream, wherein the first mode is used before an acknowledgment of receipt of an IDR picture in the outgoing bitstream is received from the receiver node, and wherein the second mode is used after the acknowledgment of the receipt of an IDR picture in the outgoing bitstream is received from the receiver node. 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, the outgoing bitstream being transmitted to a receiver node of the system, 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, including changing at least one syntax element between the incoming bitstream and the outgoing bitstream such that information about reference picture handling is changed so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions; and the processing of the incoming bitstream to change the at least one syntax element includes switching between multiple modes, the multiple modes including: a first mode in which instantaneous decoding refresh, IDR, pictures in the incoming bitstream are maintained in the outgoing bitstream; and a second mode in which IDR pictures in the incoming bitstream are converted to intra, I, pictures in the outgoing bitstream, wherein the first mode is used before an acknowledgment of receipt of an IDR picture in the outgoing bitstream is received from the receiver node, and wherein the second mode is used after the acknowledgment of the receipt of an IDR picture in the outgoing bitstream is received from the receiver node. a first mode in which instantaneous decoding refresh, IDR, pictures in the incoming bitstream are maintained in the outgoing bitstream; and a second mode in which IDR pictures in the incoming bitstream are converted to intra, I, pictures in the outgoing bitstream, wherein the first mode is used before an acknowledgment of receipt of an IDR picture in the outgoing bitstream is received from the receiver node, and wherein the second mode is used after the acknowledgment of the receipt of an IDR picture in the outgoing bitstream is received from the receiver node.