What is a group of pictures (GOP) structure?

Issue

What is a group of pictures (GOP) structure?

Product Line

Pelco Cameras

Environment

  • IP Cameras

Cause

  • GOP Information

Resolution

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.

Pelco cameras 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.

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