Specifications

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Cisco TV CDS 2.5 ISA Software Configuration Guide
OL-24788-01
Chapter 1 Product Overview
Overview
RTSP/1.0 200 OK<CRLF>
CSeq: 2<CRLF>
Session: 12345678<CRLF>
Transport: RTP/AVPF/UDP; unicast; destination=54.0.1.1; client_port=8998-7123;
source=101.1.2.3; server_port=50236-50237<CRLF>
Following is an example of the second SETUP message:
SETUP rtsp://192.0.2.100/movie.mpg/rtx RTSP/1.0<CRLF>
Session: 12345678 <CRLF>
CSeq: 2 <CRLF>
Transport: RTP/AVPF/UDP; unicast; destination=54.0.1.1; client_port=8999-7124<CRLF>
<CRLF>
RTSP/1.0 200 OK<CRLF>
CSeq: 2<CRLF>
Session: 12345678<CRLF>
Transport: RTP/AVPF/UDP; unicast; destination=54.0.1.1; client_port=8999-7124;
source=101.1.2.3; server_port=50238-50239<CRLF>
<CRLF>
Note Retransmission-based Error Repair is only available with RTP streaming.
Background
RTP packets include sequence numbers that are used to detect missing packets and reorder out-of-order
packets. RTCP is the control protocol for RTP and is used to send receiver reports from the client to the
server that include monitoring information, to send sender reports from the server to the client, and to
request retransmission, which is the RTCP NACK packet that includes the RTP sequence number.
The Streamer receives the retransmission RTCP NACK request. Each NACK request identifies one or
more missing RTP packets. The Streamer keeps a small buffer of recently transmitted packets and the
missing packets are retransmitted based on how many packets the buffer maintains.
Error Repair Client on STB
VOD Error Repair feature requires that the STB have the Cisco Visual Quality Experience Client
(VQE-C) software running on it. The VQE-C is the error-repair client software, which has the following
capabilities:
• Receives RTP video packets
• Detects missing packets
• Requests retransmission of missing packets
• Merges retransmitted packets with original stream
• Collects statistics and counters for monitoring
The VQE-C is a software development kit (SDK) that is available for download through the open-source
program. Additionally, the STB must comply with the Cisco RTSP syntax for VOD Error Repair.
Monitoring
The play management application (PMA) log file, vqe.log, is located in the /arroyo/log directory. To
check for PMA errors, enable the PMA debug flag for the vqe_cp facility on the Logging page in the
CDSM.