Video formats, modes and bandwidth
MARLIN Technical Manual
V2.4.0
152
Frame rates
An IEEE 1394 camera requires bandwidth to transport images.
The IEEE 1394a bus has very large bandwidth of at least 32 Mbyte/s for trans-
ferring (isochronously) image data. Per cycle up to 4096 bytes (or around
1000 quadlets = 4 bytes @ 400 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, there is more data
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 400 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
L
To configure this feature in an advanced register see
Table
117: Advanced register: Autofunction AOI
on page 222.
Note
L
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 66: Overview fixed formats