This Recommendation specifies requirements with regard to a scalable video transmission system over cable networks, which is one of the approaches for transmitting an additional video service (e.g., 4K) over cable networks on top of the existing video service (e.g., high definition television (HDTV)). Furthermore, this system supports scalable video coding bitstreams, which consist of a multi-layer bitstream structure, and that complies with video coding technology standards. In order to enable the provision of simultaneous video services over cable networks, this system transmits individual layer bitstreams over radio frequency (RF) and IP (data over cable service interface specification (DOCSIS) [ITU-T J.222.0]).

This Recommendation is most suitable for the case where a bit rate reduction is the highest priority because the available transmission capacity of the IP (DOCSIS) interface is insufficient for transmitting several higher quality video programs (e.g., 4K), or the remaining RF bandwidth is not sufficient to convey such programs. Another applicable case is that the gain of scalable coding is sufficiently larger than independent coding, or more specifically, scalable transmission is capable of reducing the bit amount of the higher layer (quality) stream against a simultaneously coded stream. Here, an assumption is that the higher quality video and the legacy quality video have identical angles of view, and it helps to achieve good coding gain in scalable coding.