In this case, if a stream is published as H264, VP8 or H265, and RTSP client supports the codec, the stream will be played via RTSP without transcoding. Audio codecs are detected by the same way.
Interleaved mode support
Before build 5.2.1609, WCS supported interleaved mode only, in this case both RTSP signaling and RTP traffic go via TCP, therefore some player applications (including VLC) may not play RTSP from WCS with default settings. Since build 5.2.1609, non-interleaved mode is also supported, in this case RTSP signaling goes via TCP, and RTP traffic flows via UDP. Note that non-interleaved mode is less packet loss proof.
1. Frame loss and picture artefacts can occur when HD stream is played via RTSP