Gadspot GS-N621 User Manual page 19

Stream Setting:
1: Configuration of stream 2 is the same as stream 1, but Stream 2 can only be set to 320x240 or 640x480,
2: Stream3 only RTSP path、image format and frame rate can be adjusted, the rest of the settings are fixed.
RTSP Path -
The RTSP Path is the stream ID used for RTSP client streaming connection, such as VLC player. The default
values are v00, v01 and v02 for the three streams respectively. The string can be any combination of number
or capital/small letters. It cannot be empty however.
Resolution -
The resolution here describes an image size counted by width and height, e.g. 640x480, referring to pixel
st
resolution. The 1 stream can be set from more options of resolution; 1600x1200 (2 megapixels),
1280x720(HD), 800x600(SVGA), 640x480(VGA), 320x240(QVGA). While Stream2 has the options of VGA
and QVGA, stream3 is in a fixed resolution, the QVGA.
Video Mode -
This option allows the selection of two bit rate modes, the Constant Bit Rate (CBR) or Variable Bit Rate
(VBR). CBR refers to the setting of a fixed Target Bit Rate (configuration in the rage of 64Kbps to 6Mbps)
that would apply in the case of limited bandwidth or/and storage requirement. While CBR concerns a fixed
data rate transmitting, the video quality is of high priority for VBR mode selected. VBR therefore is configured
with the Quality Level (Standard, Good, Best). In general, CBR predicts the provided condition; if image
activity requires higher bit rates than configured, the frame rate and quality would be affected as not likely to
increase bandwidth (bit rate). In spite of the required recording storage estimation, VBR is by way of
compensation that adjustable bit rate fits the actual image activity.
Image Format -
H.264 and MJPEG are available for image format selection. The term, "image format", is referring to
compression / encoding technique. The selection of image format decides the performance of bandwidth and
storage requirement. In the request of same video quality, H.264 contributes to less bandwidth and storage
requirement, which is more efficient than MJPEG.
GOP -
In H.264 video coding, GOP (group of pictures) describes how the different types of frames are arranged. The
frame types implemented here are I-frame (full image information) and P-frame (motion-compensated
difference information). This setting configures the GOP length which is the number of frames before next
I-frame appears. Having more I-frames usually increases the stream size, and therefore more bandwidth and
storage are required.
Frame Rates -
The Frame Rates defines the number of frames that will be displayed per second. The frame rate setting can
affect the target bit rate (bandwidth requirement) and storage requirement.
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