Re: [Standards] Average packet size of XEP-0301

[Gunnar Hellström]

In order to get an approximate value, we could check what we get with recommended values for the optional items. 1. I think it is quite common that the overhead in XMPP gets around 300 bytes per packet. (It might be 200 in some conditions.) 2. The recommended rate of packets is one every 700 ms as long as new text is produced. Thus 1.4 packets per second. = 420 bytes per second overhead. 3. The text plus keypress interval information is often 20 bytes per character. ( see XEP-0301 section7.9 )  5 characters per second is then 100 bytes per second. 4. The sum with this example is 520 bytes per second or 4.2 kbit/s,  in 1.4 packets per second. 5. Since the values for overhead were very coarse, we should round off to about 500 bytes/s and 4 kbit/s in 1.5 packets/s. 6. If you select options differently, you will have different results. Gunnar ___________________________________________________ Gunnar Hellström Omnitor gunnar.hellst...@omnitor.se +46708204288 Mark Rejhon skrev 2012-05-15 20:24: 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     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