CEPT T TE 06-05 E-1988 Videotex Presentation Layer Data Syntax Terminal Facility Identifier《可视图文表示层数据语法终端设施标识符》.pdf

1、 TTE06-05 Page E 1 Recommendation T/TE 06-05 (Edinburgh 1988) VIDEOTEX PRESENTATION LAYER DATA SYNTAX TERMINAL FACILITY IDENTIFIER This document describes the Terminal Facility Identifier which may be used to ascertain the capabilities of either I a physical Videotex Terminal or another Videotex Ser

2、vice. Contents 1. INTRODUCTION 2 2.REFERENCES . 2 3. DEFINITIONS . 2 4. CODING STRUCTURE . 2 5. CODING. . 2 6. DEFAULTS. 4 I Edition of September 15, 1989 -. . W 2326434 0010041 B TITE 06-05 E Page 2 1. 2. 3. 4. 5. 5.1. INTRODUCTION The Terminal Facility Identifier may be used to ascertain the capab

3、ilities of a “terminal”, (where a terminal may actually be a physical terminal or another videotex service). The TFI may be used in three ways: 1. To determine the terminal profile and additional terminal capabilities. 2. To determine to which parts of the SRM the terminal conforms. 3. To determine

4、whether the terminal can execute a particular VPDE. REFERENCES CEPT Recommendations T/TE 06-01 E up to T/TE 06-04 E. DEFINITIONS See CEPT Recommendatins T/TE 06-01 E up to TITE 06-04 E. CODING STRUCTURE Two VPCEs are used for the TFI, US 210 and US 2/1. CODING To request the terminal profile the cod

5、e US 2/0 4/0 is transmitted to the terminal. The terminal will reply with US 2/0 followed by a series of bytes from columns 4 to 7 of the code table (profiles and capabilities), or by a series of bytes from columns 4 and 5 of the code table, (representing the parts of the SRM to which the terminal c

6、onforms), terminating with the code 4/0. To determine whether the terminal can execute a particular VPDE, the service transmits the code US 210 followed by the header of the VPDE and terminated by US 2/1 to the terminal. The terminal replies with either US 210 2/0 indicating it can execute the VPDE

7、or with US 2/0 2/1 indicating it cannot execute the PVDE. Conforming to the SRM 4/0 Terminator 4/1 Alphamosaic (T/TE 06-01) 412 Geometric (TITE 06-02) 413 Photographic (T/TE 06-01) 4/4 Define DRCS (T/TE 06-01) 415 Define Colour (T/TE 06-01) 416 Define Format (T/TE 06-01) 417 Transparent data (TITE 0

8、6-03) 418 Reset (T/TE 06-01) 419 Telesoftware (T/TE 06-04) 4/11 Timing Control (T/TE 06-01) 4/10 Terminal Facility Identifier A terminal conforming to parts 1, 4, 5, 6, 8 and 10 would transmit: US 2/0, 4/1, 414, 41.5, 416, 4/8, 4/10, 4/0 If different levels of conformance are defined in the future (

9、as for the Geometric display or TSW), then the level of conformance may be indicated by one or more bytes from column 3 of the code table following the relevant byte from column 4. For the Geometric mode (primary byte 4/2) the following sub-levels will be defined: 3/0-3/7 reserved 318-3115 A termina

10、l which conforms to parts 1, 2 (sub-level coded 3/59, 4, 5, 6, 8 and 10 would transmit: US 2/0, 4/1, 412, 319, 414, 4/5, 416, 418, 4/10, 410 The sub-levels of TSW are for further study. sub-levels to be defined are for further study Edition of September 15, 1989- 2326434 O030042 T W - - Cap. byte 1:

11、 - 1101111 TITE 06-05 E Page 3 b) US 2/0 610 619 7/15 4/6 = - 1 O O O 1 1 O 5.2. Profiles The following codes for terminal profiles have been assigned: : alphamosaic profile 1 610 611 612 613 614-617 6/8 6/10-6/15 7 /O - 7 / 7 7/8-7/ 14 711 5 Extension bit if b6 = 1 : more Cap. bytes foliow if b6=0:

12、 last Cap. byte Reserved Telesoftware capability I 5.3. Ability to execute a particular VPDE The service transmits the VPDE header, (without the US code), and terminates the header with a US 2/1. If the service requires to know whether the terminal can execute 8 by 10 dot DRCS, it transmits the foll

13、owing codes to the terminal: US, 210, 213, 210, 419, US, 211 If the terminal can execute 8 by 10 dot DRCS it replies with an acknowledgement i.e. the code US 210 2/0. If it cannot it replies with the code US 210 211. (DRCS header) Edition of September 15, 1989 -, -J 232b414 OOLOO43 I T/TE 06-05 E Pa

14、ge 4 5.4. Sound capabilities Note. The following has been reserved for sound capability identification. The exact definition of sound videotex requires further study. Conformance code (first octet) : 510: Sound capability, block mode. 511 : Sound capability with framing (CEPT T/TR 01-03, CCITT Draft

15、 Recommendation Y.221). The conformance code may be followed by zero, one or more couples of octets indicating the type of coding and the audio bitrate. Algorithm identification (second and even octets) : 310: PCM A-law described in CCITT Recommendation G.711 311 : PCM mu-law described in CCITT Reco

16、mmendation G.711 312: ADPCM described in CCITT Recommendation G.721 313 : sub-band ADPCM described in CCITT Draft Recommendation G.72X Bitrate audio coding (third and odd octets): 310: 8 Kbits/s 311: 16 Kbits/s 312: 24 Kbitsls 313: 32 Kbitsls 314: 40 Kbits/s 315: 48 Kbits/s 316: 56 Kbitsls 317: 64 K

17、bits/s For example a terminal which conforms to parts 1, 2, 3 and which handles the sound capability with no framing using PCM 64 Kbits or ADPCM 32 Kbits would transmit: US 210, 411, 412, 413, 510, 310, 317, 312, 313, 410 6. DEFAULTS If no response is received from a terminal within a specified time (depending upon the transmission network being used), then the basic terminal used within that network is assumed. Edition of September 15, 1989,-