Attachment B: Bandwidth Estimation
Since the FPS is dependent on the bandwidth of the camera, the relationship between
the size of an image file and the bandwidth is always the major concern of the system
construction engineer.
The table below shows the relation between the resolution and size of an MJPEG file
in the NTSC system. Please note that the values in the table are for reference only,
because the size of an image file is closely related to the complexity of the
environment and the actual situation of the place being monitored.
Image Resolution
Average range of Data Sizes
176 x 122 (QCIF)
20 – 40k bit
352 x 240 (CIF)
40– 200k bit
640 x 480 (VGA)
180 – 400k bit
704 x 480 (D1)
200 – 530k bit
Ex.: The transmission speed on the Internet is 2fps under 352 x 240, i.e. 40k*2=80k to
200*2=400k per second. It is suggested to apply for 512K "upload" bandwidth.
Note 1: What the camera needs at the client end is the “upload” bandwidth. However, most
ISPs in Taiwan provide download bandwidth that is wider than the upload
bandwidth. Therefore, symmetrical bandwidth is a good choice for users who need
wider upload bandwidth. Ex. download/upload = 521K/512K
Note 2: 32 kbps to 64kbps is required for transmission of audio signals.
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