Tesis previa a la obtención del Título de Ingeniero en Electrónica y ...
Tesis previa a la obtención del Título de Ingeniero en Electrónica y ...
Tesis previa a la obtención del Título de Ingeniero en Electrónica y ...
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2) Vi<strong>de</strong>o paltern iransmiíted- An üleclroniüally g<strong>en</strong>eraled ur olher paltern is iransmilied inslead of Ihe sígnal<br />
/"rom a normal camera. Trie C&l RAS co<strong>de</strong> VIS (ví<strong>de</strong>o indicíale suppressed) is used lo indícale the situatian<br />
lo the remole party.<br />
3) Vi<strong>de</strong>o transmitted bal no! disp<strong>la</strong>yed - Terminal proeedures simply involve local action lo disp<strong>la</strong>y not ihe<br />
incomíng signal huí an exp<strong>la</strong>naiory symbol or me.ssage. User action would cause the incurrí ing signa! to be<br />
disp<strong>la</strong>yud, bul ií ihis should <strong>de</strong>p<strong>en</strong>d on mulual atuion by bolh usera ih<strong>en</strong> a new C£I BAS co<strong>de</strong> VRD (vi<strong>de</strong>o<br />
ready-lo-disp<strong>la</strong>y) musí be <strong>de</strong>fined. Thi.s poinl is for furlher siudy.<br />
,5 O p ti o nal <strong>en</strong>hancem<strong>en</strong>ts<br />
5.1 Bata porís<br />
ata porís as physical l/O ports oí' Ihe lermínal for lelemalk: and olher equípm<strong>en</strong>l are aclivaled/<strong>de</strong>aclíved by HAS<br />
immands. Dep<strong>en</strong>ding on Ihe transmission ciipahility of a eonneelion, e.g. mulliples of R/H(| channels, ele., varíous bit<br />
ites are avai<strong>la</strong>blt at (hese porís. AHocaiion ol'bii slmanis lo lh« pori(.s) is peri'ornied by in-band .signalling. Da<strong>la</strong> conveyed<br />
. the port(s) is iranspar<strong>en</strong>t, da<strong>la</strong> rales being lisliid in Atinex A/H.22!.<br />
,5.2 Encryption<br />
ncrypiion may be applíed on audio and ví<strong>de</strong>o sigoal.s separaiely (preferul>ly J'or mitltipoinl üonneulions) or on audio and<br />
<strong>de</strong>o signáis multiplexed. vSwíichíng-on and olí the <strong>en</strong>cryplion process has to be sigiialled beiwe<strong>en</strong> Ihe termináis (or<br />
rminal and MCU respeclively) vía ¡n-band signalling.<br />
Terminal requirem<strong>en</strong>ts<br />
,1 Environm<strong>en</strong>ts<br />
n<strong>de</strong>r sludy.<br />
.2 Audio and vi<strong>de</strong>o arrangem<strong>en</strong>ts<br />
ín<strong>de</strong>r study.<br />
.3 De<strong>la</strong>y comp<strong>en</strong>sation in the audio path<br />
lie H.261 vi<strong>de</strong>o co<strong>de</strong>es require so me. processing <strong>de</strong>.<strong>la</strong>y, while ihe H.200/A V.2.1t)-ííe.rÍes audio tm <strong>de</strong>cís involve. mucih le.s.s<br />
e<strong>la</strong>y. H<strong>en</strong>ee, if Üp synchroniy.alion is lo be rnain<strong>la</strong>ined, ihal vi<strong>de</strong>o proce.s.sing <strong>de</strong><strong>la</strong>y musí be ctomp<strong>en</strong>saled ¡n ihe audio<br />
aih. Since vi<strong>de</strong>o co<strong>de</strong>r and <strong>de</strong>c-.o<strong>de</strong>r <strong>de</strong><strong>la</strong>ys may vary acciording lo implern<strong>en</strong><strong>la</strong>iion, <strong>de</strong><strong>la</strong>y f.omp<strong>en</strong>salion musí be yarried<br />
ut indivídually al the co<strong>de</strong>r and <strong>de</strong>co<strong>de</strong>r. A refere.ncui me.asurtíme.iil melhod of vi<strong>de</strong>o co<strong>de</strong>r and <strong>de</strong>co<strong>de</strong>r <strong>de</strong><strong>la</strong>ys i.s <strong>de</strong>fined<br />
i Recomm<strong>en</strong>dalion H.261.<br />
A Control and indications (C&I)<br />
!&I are chos<strong>en</strong> from Ihe g<strong>en</strong>eral audiovisual .sel tumiained in Rr.üomni<strong>en</strong>dalion H.230. For visual lelephone systems,<br />
lose signáis m Table 4 are used mandalory, whe.re iheir sourcte., sink, synchroniy.alion wilh pif.lure, Iransmíssion channel<br />
nd co<strong>de</strong>words are ¡iidícaied.<br />
ill visual íelephone lerrninals have a vi<strong>de</strong>o .source providing a piciure o!' parlicipanls, and some termináis may nave<br />
ddítional ví<strong>de</strong>o sources; the. parlicipanl-piclure source ís <strong>de</strong>.signaied #1, havíng Ihe assoeialed symbol VÍA. Wh<strong>en</strong><br />
icoming vi<strong>de</strong>o is ON (BAS cornmand (OJO) [1 or 21) and VIA. V!A2, V1A3 have nol be<strong>en</strong> iransmiiled, sourceífl is<br />
ssumed.<br />
Jome supplem<strong>en</strong><strong>la</strong>ry services provi<strong>de</strong>d by sonie coni'ereiu:e bridges, servers, ele. may require termináis 10 s<strong>en</strong>d out the<br />
.ymbols on iheir diallíng keyboards. il ís highly <strong>de</strong>sirable. Ihai all visual lerminals be able lo irans<strong>la</strong>le ihese symbols inlo<br />
3AS co<strong>de</strong>s repres<strong>en</strong>líng Ihe Alphabel of Figure 2/T.fi] as provi<strong>de</strong>d for ín Recomm<strong>en</strong>t<strong>la</strong>iíon H.230.<br />
! Kecumm<strong>en</strong>dation H.320 (03/93) 9
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