 |
|
|
| Whitepapers/The VideoBridge concept Chapter 8 of 8 Appendix A - standardisation efforts The industry standard for mapping of MPEG-2 Transport Stream packets into IP data frames is as shown in the protocol stack figure below. The majority of triple-play networks - where television is carried to the consumer over DSL or fibre - rely on this industry standard. 
Figure 5 - The industry standard protocol stack in use when mapping MPEG-2 into IP frames. The MPEG-2/DVB layer is specified in ISO/IEC IS 13818 " Generic Coding of Moving Pictures and Associated Audio". The UDP layer is according to RFC768 "User Datagram Protocol". A variable number of 188-byte MPEG-2 TS packets is mapped straight into a UDP frame with no additional overhead. The MTU for Ethernet is usually 1500 bytes. This limits the number of MPEG-2 TS packets per UDP frame to lie within 1 to 7. The IP layer is according to RFC791 "Internet Protocol Specification". The data link layer is Ethernet according to IEEE 802.3/802.3u 10/100Mbit/s. As a side note, there are currently two ongoing standardisation efforts in this area that both have as their goal to standardise the way in which MPEG-2 Transport Streams are carried over IP infrastructure. The standardisation bureaus involved are pro-MPEG Forum and DVB. Both bodies are heading towards specifying an optional additional RTP layer to be added on top of UDP. he main reason for this approach is to allow for Forward Error Correction schemes to be added when IP networks are used to carry video for professional purposes (e.g. inter-studio video transfer). There exist two relevant specifications:
|
News
Upcoming events
