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Cisco Video Surveillance 5010/5011 Indoor Fixed HD IP Dome Camera User Guide
OL-22669-02
Chapter 3 Operation
A/V Streams Tab
Rate Control
The rate control setting determines the bit rate and quality of each frame in the video stream. There might
be a trade-off between image quality and the resources required for video storage when selecting a rate
control setting.
CBR: The constant bit rate (CBR) streams video at a fixed number of bits per second. CBR uses the full
capacity of the bit rate setting for scenes with or without motion. Video is always streamed at the user
bit rate setting.
Profile
The profile defines the subset of bit stream features in an H.264 stream, including color reproduction
and additional video compression. It is important that the selected profile is compatible with the
recording device so that a stream can be decoded and viewed.
Baseline: A simple profile with a low compression ratio. A baseline profile is compatible with more
recorders but uses more bits to compress quality video than the other profiles. This profile supports
I-frames and P-frames. Use the baseline profile in applications with limited scene changes; for example,
an indoor scene with a single, unchanging primary light source and minimal motion.
Main: An intermediate profile with a medium compression ratio. Main is the default profile setting. This
profile is compatible with most recorders and uses fewer bits to compress video than the baseline profile;
however, it uses more bits than the high profile. The main profile supports I-frames, P-frames, and
B-frames.
High: A complex profile with a high compression ratio. This is the primary profile for high-definition
television applications; for example this is the profile adopted for Blu-ray and HD-DVD. The high
profile supports I-frames, P-frames, and B-frames.
GOP Structure
The group of pictures (GOP) structure is the sequence in which frames are placed within a video stream.
The GOP structure always includes intra-coded frames (I-frames) and predictive coded frames
(P-frames), but it can also include bi-directionally predictive coded frames (B-frames).
Each GOP structure starts with an I-frame: an image of the complete scene that is used as the reference
frame in the structure. P-frames record data changes that are different than the previous frame. This
allows the video encoder to save space since the data of the I-frame is not duplicated. B-frames not only
capture data changes from the previous frame, but they also capture the data changes from the frame
after the B-frame. B-frames are more compressed than P-frames and require more processing power to
be decoded.
Note Do not change the following GOP settings when using the cameras with Cisco Video Survelliance
Manager (Cisco VSM). Always use the default settings. The following descriptions are for informational
purposes only.
The camera can be configured to use one of the following GOP structures:
• IP: A compression that uses only I-frames and P-frames to provide low latency and a high level of
decoder support. This GOP structure is compatible with more recorders and decoders than IBBrBP.
• IBBrBP: The most sophisticated H.264 compression available. IBBrBP provides the highest quality
image at a given bit rate, but it also increases the latency of the video and requires more processing
power for decoders.