Instruction manual

Video formats, modes and bandwidth
10.7 Frame rates
e IEEE-1394a bus has very large bandwidth of at least 32 MB/s for transferring (isochronously)
image data. Per cycle up to 4096 bytes (or around 1000 quadlets = 4 bytes) 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.
e following tables indicate the volume of data in various formats and modes to be sent within
ne cycle (125µs) at 400 Mb/s o w
The tables are divided into three formats; F_0 up to VGA, F_1 up to XGA, and F_2 up to UXGA.
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.
An IEEE-1394 camera requires bandwidth to transport images.
Th
Th
o f band idth.
Format Mode Resolution 60
fps
30
fps
15
fps
7.5
fps
3.75
fps
0
160 x 120 YUV (4:4:4)
24 bit/pixel
1/2H
80p
60q
1/4H
40p
30q
1/8H
20p
15q
1
320 x 240 YUV (4:2:2)
16 bit/pixel
1H
320p
160q
1/2H
160p
80q
1/4H
80p
40q
1/8H
40p
20q
2
640 x 480 YUV (4:1:1)
12 bit/pixel
2H
1280p
480q
1H
640p
240q
1/2H
320p
1/4H
160p
60q
120q
3
640 x 480 YUV (4:2:2)
16 bit/pixel
2H
1280p
640q
1H
640p
320q
320p
160q
1/4H
160p
80q
1/2H
4
640 x 480 RGB
24 bit/pixel
2H
1280p
960q
1H
640p
480q
1/2H
320p
240q
1/4H
160p
120q
5
640 x 480 (MONO8)
8 bit/pixel
4H
2560p
640q
2H
1280p
320q
1H
640p
160q
1/2H
320p
80q
1/4H
160p
40q
6
640 x 480 Y (MONO16)
16 Bit/pixel
2H
1280p
640q
1H
640p
320q
1/2H
320p
160q
1/4H
160p
80q
0
7
640 x 480 Y (MONO16)
Reserved
Table 59: Format_0
As an example, VGA MONO8 @ 60 fps requires four lines (640 x 4 = 2560 pixels/byte) to transmit
every 125 µs: this is a consequence of the sensor’s line time of about 30 µs, so that no data
needs to be stored temporarily. It takes 120 cycles (120 x 125 µs = 15 ms) to transmit one
frame, which arrives every 16.6 ms from the camera. Again no data need to be stored
temporarily.
Thus around 64 % of the available bandwidth is used.
MARLIN Technical Manual
Page 116