Axis P1365 Mk II User Manual page 21

AXIS P1365 Mk II Network Camera
Video and Audio
• 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.
• Mirror image. If required, the image can be mirrored.
• Rotate image. If required, the image can be rotated.
• 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 About overlay text on page 26.
Click Save to apply the new settings.
About 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 bitrates.
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.
About GOP length
A Group of Pictures (GOP) contains one I-frame followed by a number of P-frames. The GOP length is the number of frames
between two I-frames.
If you set the GOP length and the frame rate equally you will get one GOP per second. If you change the GOP length to a higher
value you will get more small sized P-frames and less big sized I-frames while keeping the same frame rate. In other words, a high
GOP-length value saves bandwidth, but the video quality may decrease. A low GOP-length value increases the video quality
but needs more bandwidth.
About H.264 profiles
The Axis product supports the following H.264 profile(s):
• Baseline: Use the Baseline profile if the client does not support CABAC entropy coding.
• Main: The Main profile uses CABAC and provides a better compression with maintained video quality. It requires a larger
amount of processing power to decode than the Baseline profile.
• High: The High profile provides a higher compression than both Main and Baseline profiles, but requires more processing
power to decode. High profile supports 8x8 blocks, which reduces the bitrate further compared to the Main profile.
About bitrate control
Bitrate control is useful to make sure the video streaming does not take up too much bandwidth.
The built-in bitrate control can be combined with Zipstream, see About Zipstream on page 22. We recommend using a high bitrate
limit to enable the full potential of Zipstream.
About variable bitrate
Variable bitrate (VBR) adjusts the bitrate according to the image complexity. When the activity in the scene increases, VBR adjusts
the bitrate according to the complexity, using up more bandwidth for increased activity in the scene, and less for lower scene activity.
Variable bitrate is suitable if there is a surplus in bandwidth, where the increased bitrate may not be an issue.
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