TC620-PID
Page 104
13.3.7
RTSP Transmitter
Audio > Advanced > RTSP Transmitter
Item
Description
DSCP field
Range: [0...63]. DSCP (Differentiated Services Code Point) uses the first 6 bits of the
ToS (Type of Service) field in the header of IP packets for packet classification
purposes. The bit pattern in the field indicates the type of service and forwarding
behavior at the next node. With 26 bits, up to 64 network service types can be
defined.
RFC 2724
(
http://www.ietf.org/rfc/rfc2474.txt
) describes the
Differentiated Services (DS) field and the DiffServ Code Point. See also the note on
Differentiated Services later in this chapter.
Default multicast IP
address
Destination IP address for multicast sessions.
Default multicast IP
port
Port number for multicast sessions.
Note on Differentiated Services:
Differentiated Services (DiffServ, or DS) is a method for adding
QoS (Quality of Service) to IP networks. In routed networks, critical network traffic such as video
and audio streams, which require a relatively uninterrupted flow of data, can get blocked due to
other traffic. DiffServ can be used to classify network traffic and give precedence - i.e.
low-latency, guaranteed service - to high-priority traffic, while offering best-effort service to
non-critical traffic such as file transfers or web traffic.
Each stream has a DSCP (Differentiated Services Code Point) field in the IP header. Routers will
identify the network service type in the DSCP field and provide the appropriate level of service.
Low-latency service can be realized, for example, through priority queuing, bandwidth
allocation, or by assigning dedicated routes.
Note on RTP and RTCP:
The Real-time Transport Protocol (RTP) is designed for end-to-end
real-time, audio or video data flow transport. It is regarded as the primary standard for
video/audio transport over multicast or unicast network services. RTP does not provide
guaranteed delivery, but sequencing of the data makes it possible to detect missing packets. It
allows the recipient to compensate for breaks in sequence that may occur during the transfer on
an IP network. Error concealment can make the loss of packets unnoticeable.
RTP is usually used in conjunction with the Real-time Transport Control Protocol (RTCP). RTP
carries the media streams. RTCP provides reception quality feedback, participant identification
and synchronization between media streams.
