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Subject: IF Broadcast Pointers
Following up from the IF discussion this morning, hope this helps move things along. Note these are true IF level specs where referenced (i.e. packet level encapsulation and transport delivery) -- not application layer transport abstractions. For broadcast we have a couple of breakdowns for the USA marketplace. === Digital Cable: http://www.scte.org/documents/pdf/SCTE182002ANSIJSTD042DVS208.pdf Defines the injection of EAS for cable networks using OOB broadcast. This is a cable_emergency_alert message inside an MPEG2 ts (transport stream). Digital cable set top boxes can be triggered with messages using this. We've implemented this at RCN, Comcast and I believe a few others with a product called DEAS. === Analog Cable and Analog terrestrial/OTA (over the air): http://www.chyrongraphics.com/products/codi/index_b.html#codieas Since there is no universal addressability for analog systems (VBI is not ubiquitously supported), automated character generators are used. Above is one. Basically a simple video re-encoder with an overlay text crawl. Oxtel, Matrox, and others do the same thing. One can classify these systems as legacy, since when analog NTSC is phased out they will cease to be used in favor of table packet injection as described above and below. === ATSC (digital terrestrial/OTA): http://www.atsc.org/standards.html For delivery to digital set top boxes in the realm of SI (service information (mpeg ts metadata)) data the following are pertinent: a/65b. For delivery of data to PC or TCP stack capable receivers, the following are pertinent: a/90, a/92. A/92 and A/65b are the most widely 'used'. We're currently using A/92 for CAP transport via a product called AlertStorm. Triggering of alerts for digital set top boxes is still up in the air, but the most likely candidate is a DCC (directed channel change) trigger, to force receivers to tune to a channel, and then tune back (the last part is not implemented or specced yet) to the original channel after the emergency notification is completed. A/92 is the only viable injection method currently, as settop boxes do not support DCC, and most stations use static PSIP table servers/injectors. One must implement a metadata channel for description of content details and addressability. All A/92 vendors do this in their own way, but in a way so as not to be specific to any datatype. Please note that although A/92 defines SDP for metadata, it is *not* sufficient for anything but basic data descriptors. To be blunt, no-one uses it. Also note that many A/92 systems can be deployed on any IP system, and transparently carried over UDP-capable networks (i.e. satellite to terrestrial to lan to WIFI to NexTel, etc.) and decoded by any OS embedded or other with multicast-capable TCP stack. === Satellite (directv, echostar, etc.): These providers use either DVB or proprietary transport streams. DVB resembles ATSC in some ways. Commercial satellite providers roll out receivers to their specifications, and each provider requires a proprietary alert injection system (if supported at all). This is too big a nebulous to cover and the best approach is probably to blanket these services under proprietary/custom. The IFSC one-way data delivery document adds some bulk to these comments. I think that covers it all. If we need to look at worldwide broadcast standards then this list will need a lot of addition and refinement. Cheers Kon *********************************************************************************** Information contained in this email message is intended only for use of the individual or entity named above. If the reader of this message is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the postmaster@nds.com and destroy the original message. ***********************************************************************************
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