Guppy PRO Technical Manual
V4.1.2
165
Frame rates
An IEEE1394 camera requires bandwidth to transport images.
The IEEE1394b 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.
Note
All bandwidth data is calculated with:
1 MByte = 1024 kByte
Format
Resolution
Max. video format
Format_0
up to VGA
640 × 480
Format_1
up to XGA
1024 × 768
Format_2
up to UXGA
1600 × 1200
Table 87: Overview fixed formats
