User`s guide

Configuring Video Compression
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Each GOP structure has a GOP period, which is the interval between two successive
occurrences of the GOP structure, exclusive of the I-frame. Table 3-3 defines the GOP
period for each supported GOP structure.
Caution: Attempts to apply unsupported GOP structures may generate unpredictable
results.
Each GOP structure provides variable compression encoding, though longer GOP
structures typically produce higher video frame compression, thereby reducing video
storage consumption during ingestion. Longer GOP structures have a drawback: they
potentially introduce information loss through the encoding compression operation. The
vtr.media.mpeg.bit_rate control, when set to a very low compression rate (less
than 10000000), may contribute to information loss during encoding, though information
loss depends on scene content changes and several other factors. Information loss arising
from too much compression may occur during playout in the form of poor image
reproduction or unwanted image artifacts.
For each supported GOP structure, the default GOP size is 1. There are many
combinations of GOP size and GOP structure. These combinations are restricted by the
following rule: the GOP period must evenly divide the GOP size.
Caution: Failure to obey this rule may lead to unpredictable results.
Table 3-3 Supported GOP Structure and Period
GOP Structure GOP Period
I1
IP 1
IPB 2
IPBB 3
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