Hello Darren, The bitrate can pretty much range from less than 100 bytes a second (when XEP-0138 compression is used) to several kilobits per second (with Natural Typing at 300ms transmission intervals). Even at the worst case scenario, several kilobits per second is less bitrate than a cell phone call. Also, zero bandwidth is used when typing is not occuring. Also, there is a huge amount of variables that determine the bandwidth, some of which can be controlled by the software implementation:
The biggest impact on bandwidth of XEP-0301 are as follows: (1) Is key press intervals being preserved? (Natural Typing) (uses more bandwidth) Section 6.1.1 at http://xmpp.org/extensions/xep-0301.html#text_presentation Animation: http://www.realjabber.org/real_time_text_demo.html (2) What transmission interval is being used? (shorter uses more bandwidth) Section 4.4 at http://xmpp.org/extensions/xep-0301.html#transmission_interval (3) Is XEP-0138 stream compression being used? (uses less bandwidth) See http://xmpp.org/extensions/xep-0138.html (4) Are you using an optimized XMPP server that keeps headers compact? (i.e. eliminates a lot of XMPP payloads such as noarchive indicators or <x> tags). This overhead is added by Google Talk's servers and adds an additional >100 bytes per <message> packet. Also, to help get started if you wish, are welcome to take my Apache 2.0 source code (commercial use allowed) to help make it easier to implement XEP-0301 in your network: C# -- http://code.google.com/p/realjabber/source/browse/trunk/CSharp/RealTimeText.cs Java -- http://code.google.com/p/realjabber/source/browse/trunk/Java/src/RealTimeText.java My XEP-0301 standard is designed precisely for the purposes you're interested in! Once you can answer the variables #1,2,3,4, I can give you more accurate bandwidth estimates to your questions. Cheers, Mark Rejhon, deafie & computer programmer Author of XEP-0301 On Mon, May 14, 2012 at 6:25 AM, Darren Sturman < darren.stur...@teligent.co.uk> wrote: > Hi Mark**** > > ** ** > > I am proposing the use of XEP-0301 for Web and Smart Phone apps for a deaf > telephony system in the UK.**** > > ** ** > > Could you give me an estimate of the bandwidth requirements for the > following:**** > > **· **Connected user who is idle**** > > **o **I am assuming “XEP-0199: XMPP Ping” which from a forum I see is > approx. 22 bytes/second – is this correct?**** > > **· **Connected user conversation**** > > **o **What is the average packet size assuming one packet is > transmitted per second?**** > > **o **Assuming an average user types at 60 words per minute**** > > **§ **This would equate to 1 word per second which is classified as an > average of 5 characters**** > > **§ **What is the XMPP packet size minus the actual typed text? I have > seen on one forum that is approx. 200 bytes**** > > **· **So 200 bytes plus 5 bytes for 5 typed characters?**** > > ** ** > > ** ** > > Kind Regards**** > > ** ** > > *Darren Sturman BSc (Hons) IT & Comp; MSc Soft Dev* > > *Senior Software Engineer***** > > ** ** > > Teligent Limited**** > > Teligent House**** > > 2 Kings Hill Avenue**** > > Kings Hill, West Malling**** > > Kent ME19 4AQ**** > > England, UK**** > > ** ** > > Telephone: +44 (0) 1732 879 694**** > > Mobile: +44 (0) 7968 130 668**** > > Facsmile: +44 (0) 1732 879 601**** > > Email: darren.stur...@teligent.co.uk**** > > Skype: darren.sturman.teligent**** > > Website: www.teligent.co.uk**** > > ** ** > > [image: Description: cid:image001.gif@01CAC4EF.5BFD8690]**** > > ** ** > > Disclaimer: **** > > The information in this email is confidential. The contents may not be > disclosed or used by anyone other than the addressee. If you are not the > intended recipient, please notify the sender immediately at the above > address. The sender cannot accept any responsibility for the accuracy or > completeness of this message as it has been transmitted over a public > network. If you suspect that the message may have been intercepted or > amended, please contact the sender.**** > > ** ** > > Teligent Ltd is registered in England and Wales, registration number > 2893478, registered office Lion House, Red Lion Street, London WC1R 4GB. > VAT registration GB639938577**** > > ** ** >
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