Talk:AES47
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I have expended in the Wiki entry here with more detail for discussion. Interest by the professional media production in using native Asynchronous Transfer Mode networks has increased recently. In these environments, extremely low latency and very high quality of service are required to handle linear audio and video streams along side extremely large file transfers. From work carried out at BBC R&D (see http://www.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP074.pdf ) IP based network only seem viable in this area if they remain completely private and restricted in isolated single use “islands”. Also, given the dangers of these islands being accidentally (or purposefully) compromised, using ATM in its native form becomes interesting. This does not mean that business IP structure is also passed over ATM as well. Clearly this is best left to Ethernet within media production structures as this is a far more cost effective method for networking business and file based production traffic. However, by leaving a parallel ATM path to deal with the live linear audio and video routes over the same structured cabling provide an extremely powerful way of providing a live, linear media production structure along with a method of providing distributed media routing throughout the production environment in a robust and secure way. This is a much cheaper approach than traditional point-to point broadcast and production structures within the larger companies. Towards this goal standards are being developed such as AES47 (IEC 62365), which can be studied at http://www.aes.org/publications/standards/ by downloading courtesy copies of AES4-2002 and AES-R4-2002. The leap in thinking is not to use ATM to pass IP traffic (apart from management traffic) but to use it in parallel to deal with extremely high performance secure media streams. If anyone is interested in discussing this approach, do put your views here.
Chris
I have carried out some edits to the main article to make the text clearer and added a reference to AES11 that has recently been changed to include timing of AES47 distributed audio.
I have added a background and introduction sections to the article to add context as requested by Wikipedia. Have I done enough to make this article clear?
Chris
Good article but I have a problem with finding Annex D in either of AES11-1997 or AES11-2003. AES11-2003 has only Appendix A-C and AES11-1997 has no appendixes. A discussion on how to provide synchronization between studios at different sites should be interesting with regard to the hard timing requirements of AES/EBU audio.
Bengt
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You need to download the November 2005 printing of AES11-2003. AES 11 had some minor amendments last year and Annex D was added then. The changes and additions not forming part of the body of the publication, the AES did not issue a new revision in this case, just a revised "printing". Try downloading a “courtesy” copy from the AES standards site, which is free, it will just be print and copy restricted. (Unless you are an AES member in which case full download copies are free anyway). You then will find Annex D.
Chris
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Probably didn't make it to the "courtesy" copy since I downloaded the Printing Date: 2006-02-28 version (which is the only one available from the web) and it has only Appendixes A-C. The November printing was just a draft I believe but since there was no comments on it, it should have maked it into the final 2006 version. You better double check... Anyway I think a discussion on timing issues, such as jitter and wander when transporting AES/EBU audio over a wide area network would be interesting in this article.
Bengt
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That's odd! The last printing of AES11-2003 is marked 2005-11-21 on the right hand side of the footer, there is no printing (version) newer than that for AES11. I have just down loaded a fresh copy from "http://www.aes.org/publications/standards/" and annex D is certainly present (in the courtesy copy as well). Please give it another go from this link. Your copy should have 2005-11-21 printed on the bottom right of each page.
Yes, I don't mind having a discussion on wide area timing but it will help if you can see the same content from AES11 as I can as I think most of the problems have been addressed here and with products using this principle. Let me know how you get on.
Chris
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For those interested in the timing of digital audio across AES47 networks, the AES has just published AES53, which may be helpful. Take a look!
Chris
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For those interested in the uses AES47 has been put to, the contractors supplying the wide area live high quality audio for the BBC across the UK has installed AES47 circuits. These are now in use and I understand that typical end-to-end audio latency between UK cities is around 9 ms in each direction making them very suitable for use in live multi-centre production.
Chris
