Dialogic 6.2 User Manual
Page 53
The Bfv API Functions
November 2009
53
The strip parameters infopkts:
INFOPKT_ASCII_STRIP_PARAMETERS
INFOPKT_G3_STRIP_PARAMETERS
define the actual strips of data that make up a page and must
precede an ASCII or G3 data type infopkt only to change the default
or previously applied strip parameter values (see Volume 6,
Appendix E in the Bfv API Reference Manual for default values).
Dialogic, however, recommends that you include a strip parameter
infopkt whenever you define a strip, even if the default values are
appropriate for the strip. Strip parameters include the basic format
of the data (that is, ASCII or G3 data) and presentation parameters
such as vertical resolution, width, and, in the case of ASCII, left and
right margins.
Strip parameters ensure that the strip data is sent out properly and
the received fax is displayed with the proper proportions. The
module converts strip data to the proper vertical resolution before
transmitting it.
For example, if the T.30 document resolution is set to fine resolution,
and a G3 strip is in normal resolution, the firmware converts the
data to fine resolution, replicating each line. Likewise, if the T.30
document resolution is set to normal resolution, and a G3 strip is in
fine resolution, the firmware converts the data to normal resolution,
removing every other line. If the T.30 document resolution and a
G3 strip resolution are the same, the module transmits the data
as-is. The vertical resolution of the strip data informs the module
when to convert data and how to convert it.
When ASCII strip data is sent to the module, the current vertical
resolution parameter is set to normal, even if an
INFOPKT_ASCII_STRIP_PARAMETERS
infopkt is inserted into the
infopkt stream. Thus the resolution of any G3 strip data,
encountered later in the infopkt stream, is also assumed to be
normal, unless otherwise specified by an accompanying
INFOPKT_G3_STRIP_PARAMETERS
infopkt.
When two consecutive G3 strips of data are sent to the module, an
INFOPKT_G3_STRIP_PARAMETERS
infopkt must be inserted
between them. Since each G3 strip data ends with an RTC marker
(six consecutive end-of-line codes) that is interpreted by the module
as the end of the strip of data, an INFOPKT_G3_STRIP_PARAMETERS
infopkt is required to indicate the beginning of the second G3 strip.