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Subject: Re: [emergency] IF Broadcast Pointers
Thanks Kon, This is a nice kick in the pants. Summarizing the current state of web services will take a bit of work, since some things are baked, some nearly baked, some really half-baked, and some not in the mixing bowl yet. But this, along with your previously uploaded EMIF-SC One-way Data Delivery file, is an inspiration. Ciao, Rex At 12:38 PM -0700 8/10/04, Kon Wilms wrote: >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. >*********************************************************************************** > >To unsubscribe from this mailing list (and be removed from the >roster of the OASIS TC), go to >http://www.oasis-open.org/apps/org/workgroup/emergency/members/leave_workgroup.php. -- Rex Brooks GeoAddress: 1361-A Addison, Berkeley, CA, 94702 USA, Earth W3Address: http://www.starbourne.com Email: rexb@starbourne.com Tel: 510-849-2309 Fax: By Request
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