AXIS Q7404 Video Encoder
Video and Audio
•
Video & Audio > Video Stream
. Under
Preview
, click
Open
and select the
Show pixel counter
option to enable the
rectangle in the image. Use the mouse to move and resize the rectangle, or enter the number of pixels in the
Width
and
Height
fields and click
Apply
.
•
The Live View page in Internet Explorer with AXIS Media Control (AMC) in Windows. Right-click in the image and select
Pixel counter
. Use the mouse to move and resize the rectangle.
Image
The default image settings can be configured under
Video & Audio > Video Stream
. Select the
Image
tab.
The following settings are available:
•
Resolution
. Select the default resolution.
•
Compression
. The compression level affects the image quality, bandwidth and file size of saved images; the lower the
compression, the higher the image quality with higher bandwidth requirements and larger file sizes.
•
Rotate image
. If required, the image can be rotated.
•
Color setting
. Select either
Color
or
Black & White
.
Black & White
uses less bandwidth than Color.
•
Mirror
. If required, the image can be mirrored.
•
Maximum frame rate
. To avoid bandwidth problems, the frame rate allowed to each viewer can be
Limited to
a fixed
amount. Alternatively, the frame rate can be set as
Unlimited
, which means the Axis product always delivers the highest
frame rate possible under the current conditions.
•
Overlay settings
. See
Overlay, on page 20
.
Click
Save
to apply the new settings.
H.264
H.264, also known as MPEG-4 Part 10/AVC, is a video compression standard that provides high quality video streams at low bit rates.
An H.264 video stream consists of different types of frames such as I-frames and P-frames. An I-frame is a complete image whereas
P-frames only contain the differences from previous frames.
The
GOV length
is the number of frames between two consecutive I-frames. Increasing the GOV length may save considerably on
bandwidth requirements in some cases, but may also have an adverse affect on image quality.
The bit rate can be set as
Variable Bit Rate
(VBR) or
Constant Bit Rate
(CBR). VBR adjusts the bit rate according to the image
complexity, using up more bandwidth for increased activity in the image, and less for lower image activity. CBR allows you to set a
fixed
Target bit rate
that consumes a predictable amount of bandwidth. As the bit rate would usually need to increase for increased
image activity, but in this case cannot, frame rate and image quality are affected negatively. To partly compensate for this, it is
possible to prioritize either frame rate or image quality. Not setting a priority means that frame rate and image quality are equally
affected. You must save your settings before they can take effect.
The current bit rate can be set to appear as text overlay. To do this, select the
Include text
check box option under
Overlay
Settings
and enter the modifier
#b
in the field.
MJPEG
Sometimes the image size is large due to low light or complex scenery. Adjusting the maximum frame size helps to control the
bandwidth and storage used by the Motion JPEG video stream in these situations. Setting the frame size to the
Default
setting
provides consistently good image quality at the expense of increased bandwidth and storage usage in low light. Limiting the frame
size optimizes bandwidth and storage usage, but may give poor image quality. To prevent increased bandwidth and storage usage,
the maximum frame size should be set to an optimal value.
19
