This low cost Video over IP implementation bridges an MPEG transport stream with an Ethernet-based Internet Protocol network. The design uses real time transport protocol encapsulation, and Pro-MPEG Code of Practice #3 (CoP3) forward error correction

By Tam Do Senior Technical Marketing Manager, Altera Corporation
Courtesy of Video Imaging DesignLine Jun 01, 2007

Rate this article WORSE | BETTER 1 2 3 4 5

Distribution of video through cable plants and other private networks is moving to Video over IP. IP networks are used continuously with growing popularity for carrying video, voice and data in a triple play scheme. With this move comes the requirement of low cost solutions that must address the quality of service (QoS) due to packet corruption over long distance and multi-channel requirements. The same IP network that was designed for non-real time data is now tasked with handling high-speed real time video traffic to consumers. This article highlights a low cost Video over IP with Pro-MPEG FEC reference design utilizing an FPGA.

This low cost Video over IP implementation makes up a system bridging an MPEG transport stream (TS) data with an Ethernet-based Internet protocol (IP) network. The reference design can accept TS data from several inputs and encapsulate it for transmission over an Ethernet network. Figure 1 shows a typical Video over IP application in a real system. The design uses an industry standard user datagram protocol (UDP)/IP network encapsulation, with real time transport protocol (RTP) encapsulation, and Pro-MPEG Code of Practice #3 (CoP3) forward error correction (FEC) available as an option. The design supports both 100 megabits per second (Mbps) (full-duplex) and 1 gigabit per second (Gbps) Ethernet connections. By using hardware encapsulation, the design can achieve line-rate gigabit Ethernet performance with minimal transmission latency. The design can also accept traffic from an Ethernet network and recover the TS data. For RTP encapsulated data, the design includes a receiver buffer to absorb network jitter and correct for packet reordering and duplication. CoP3 FEC-based lost packet recovery is available as an option.

View full size

Figure 1: Typical video over IP infrastructure

One of the methods for ensuring a minimum level of data integrity in an IP environment is using payload aware processing. Payload aware processing involves IP encapsulation, timing correction, and application layer forward error correction (FEC). A link level FEC is not sufficient to prevent packet loss due to burst noise from the transmission channel. Therefore by embedding the FEC into the payload aware device can reduce packet loss to a minimum. Altera has developed a Video over IP reference design that demonstrates the transmission of MPEG-2 TS data over IP-based networks with Pro-MPEG Code of Practice #3 forward error correction.

The Pro-MPEG Wide Area Network (WAN) working group is focused on establishing interoperability practices for systems that provide the exchange of high-quality programming material over wide area networks using IP. This group has produced a code of practice for the transmission of professional MPEG-2 TS data over IP networks. The code of practice recommends the transmission protocol (for example, RTP/UDP/IP mapping), a forward error correction (FEC) scheme, and also discusses issues such as timing recovery, jitter tolerance, and latency. The recommendations for the transmission protocol have been followed in this reference design, although the use of RTP has been made optional to support legacy standards based just on UDP/IP.

Next: Pro-MPEG FEC