IPTV supports multicast and unicast transmission of TV content. Multicast transmits the same content to multiple receivers simultaneously, while unicast transmits different content to each receiver. Video and audio are encoded using codecs into a compressed transport stream. The Real-time Transport Protocol controls media servers by issuing commands and maintains state between clients and servers for unicast transmission. Quality of experience for IPTV relies on error-free delivery to avoid issues like pixelation.