Specifications

1-8
Cisco TV CDS 2.5 ISA Software Configuration Guide
OL-24788-01
Chapter 1 Product Overview
Overview
If play starts at 0 or some point before the live point, then the Catch-up to Live feature allows the
end-user to fast-forward to the live point and resume normal play at the live point. The play point will
be within 2.5 seconds of the live point.
Play While Ingesting the Same Content
While ingesting the content, a STB can request the content play start at 0, at “play now,” or at any specific
normal play time (NPT) value between 0 and the live point; and the content will begin playing at the
requested point of play.
When a set-top box (STB) sends a “play now” request, meaning the STB is requesting that the play begin
at the live point, the “play now” point is within 2.5 seconds of the live point.
VOD Error Repair
The VOD Error Repair feature retransmits lost packets to improve the quality of the end-user video
experience. The VOD Error Repair feature uses negative acknowledgement (NACK) retransmission
methods to implement retransmission-based error repair.
Note VOD Error Repair is supported on ISA environments that use the Cisco (RTSP) setting as the LSCP
Client Protocol, and RTSP environments that use the Cisco RTSP deployment type.
In addition to UDP streaming, unicast Realtime Transport Protocol (RTP) with Realtime Transport
Control Protocol (RTCP) streaming, as well as Error Repair (ER) are supported.
The client dictates which streaming protocol is used by way of the RTSP SETUP message. The following
streaming protocols are supported in the same system with simultaneous streams of each type:
• UDP
• RTP
• UDP with NAT traversal (Interactive Connectivity Establishment [ICE])
• RTP with NAT traversal (ICE)
• RTP with retransmission-based error repair
• RTP with NAT traversal (ICE) and retransmission-based error repair
For sessions that use UDP, aside from RTSP messages, only the media server sends packets.
For sessions that use RTP, RTCP packets may be sent from the server to the client or from the client to
the server. The client must be aware of the server’s IP address and ports for receiving these packets.
For sessions that use NAT, the server sends its own IP address and ports as ICE candidates.
For sessions that do not use NAT, the transport header must include a “server ports” parameter.
For sessions that use RTP retransmission-based error repair, a client sends a second SETUP request to
the CDS Control server, which requires a total of four open ports. The first SETUP message has two ports
(one for RTP and one for RTCP). and the second SETUP message has two ports that carry two ICE
candidates. The URLs used for the retransmission stream are appended with the “/rtx” ending.
Following is an example of the first SETUP message:
SETUP rtsp://192.0.2.100/movie.mpg RTSP/1.0<CRLF>
CSeq: 2 <CRLF>
Transport: RTP/AVPF/UDP; unicast; destination=54.0.1.1; client_port=8998-7123,
MP2T/DVBC/UDP; unicast; destination=54.0.1.1; client_port=8998<CRLF>