beautypg.com

Frame rates, S in chapter – ALLIED Vision Technologies Stingray F-504 User Manual

Page 242

background image

Video formats, modes and bandwidth

STINGRAY Technical Manual V4.4.4

240

Frame rates

An IEEE 1394 camera requires bandwidth to transport images.

The IEEE 1394b bus has very large bandwidth of at least 62.5 MByte/s for
transferring (isochronously) image data. Per cycle up to 8192 bytes (or
around 2000 quadlets = 4 bytes@ 800 Mbit/s) can thus be transmitted.

Depending on the video format settings and the configured frame rate, the
camera requires a certain percentage of maximum available bandwidth.
Clearly the bigger the image and the higher the frame rate, the more data is
to be transmitted.

The following tables indicate the volume of data in various formats and
modes to be sent within one cycle (125 µs) at 800 Mbit/s of bandwidth.

The tables are divided into three formats:

They enable you to calculate the required bandwidth and to ascertain the
number of cameras that can be operated independently on a bus and in which
mode.

Abbreviations (used according IIDC 1394-based Digital Camera
Specification):

H means line/packet

p means pixel/packet

q means quadlet/packet

Note

All bandwidth data is calculated with:

1 MByte = 1024 kByte

Format

Resolution

Max. video format

Format_0

up to VGA

640 x 480

Format_1

up to XGA

1024 x 768

Format_2

up to UXGA

1600 x 1200

Table 92: Overview fixed formats