PacketBuffer will ignore any non-idr frame which is firs packet has not is_first_packet_in_frame set to true if there was a packet loss in the previous frame even if the cseqs are continous: https://issues.webrtc.org/issues/368335257#comment14 This CL sets this flag to true to SEI and PPS nal units that would have caused the delta frames after an idr frame to be dropped in case of loss. Bug: webrtc:368335257 Change-Id: Ic7150297d7fb4ed274c7d99175ff367100b5cf75 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/364241 Reviewed-by: Sergey Silkin <ssilkin@webrtc.org> Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43168}