Table of Contents
Advertisement
Flags:
The 2 flag bytes are used to tell the VideoReQuest whether you do or do not want to use
certain features. Setting both to 00h turns off all options. Each byte is broken up into 8 bits.
Each bit is a flag for a certain feature. The possible options are as follows:
Byte 1
Bit 8
Bit 7
Bit 6
Bit 5
Example:
To turn on the use of Check Sums, but not Acknowledgments, send 00h, 01h for the flag
bytes. This should be done on initialization of the connection as well as for any subsequent
command sent.
Data Size:
2 byte value that contains the length (in bytes) of the data portion of the command string.
For Command Subtypes 1, 2, or 3, use the Subtype table on page 4 to determine the data
length. For Command Subtype 4, the following example illustrates how to calculate the
Data Size:
Assume the length of the string is 25 bytes (25 characters, including spaces and
punctuation). This means that the full Data Size is 25 bytes PLUS 3 bytes for the
Engine, Mode, and Checksum, or 28 bytes total.
28
BYTE 1 =
= 0, or 00h
255
Header Check Sum:
If you are not using Check Sum (based on your Flag settings), then set this byte to 00h.
Otherwise, see Calculating Checksum on page 6 for more information.
Engine:
The Engine is simply the page that the VideoReQuest is currently on. Setting the Engine byte
to FFh sends the command to whatever the current Engine is. Setting the Engine byte to a
specific engine (see table) sends the command to that engine ONLY.
Engine
00h
01h
02h
FFh
Mode:
The Mode is reserved for future use, and should always be set to FFh.
Data:
These byte(s) are the actual command and possible arguments that you are sending to the
VideoReQuest. See Data Commands on the next page for a complete list of commands.
Phone (518) 899-1254 • Fax (518) 899-1251 •
Bit 4
Bit 3
Bit 2
Bit 1
Description
Sends command to Browse mode
Sends command to Player mode
Sends command to DVD player
Sends command to default (current) engine
VideoReQuest Protocol Guide v1.1.2 - 5/18/04
Bit 8
Bit 7
Bit 6
BYTE 2 = 28 MOD 255 = 28, or 1Ch
www.request.com
5 -
-
Byte 2
Bit 5
Bit 4
Bit 3
Bit 2
ACK
Bit 1
Chk
Sum
Advertisement
Table of Contents
