VIVOTEK
78 - User's Manual
■ Intra frame period
Determine how often to plant an I frame. The shorter the duration, the more likely you will get better
video quality, but at the cost of higher network bandwidth consumption. Select the intra frame period
from the following durations: 1/4 second, 1/2 second, 1 second, 2 seconds, 3 seconds, and 4 seconds.
■ Dynamic Intra frame period
High quality motion codecs, such as H.265 or H.264, utilize the redundancies between video frames to
deliver video streams at a balance of quality and bit rate.
The encoding parameters are summarized and illustrated below. The
I-frames
are completely self-
referential and they are largest in size. The
P-frames
are predicted frames. The encoder refers to the
previous I- or P-frames for redundant image information.
P I P P P P P P P P P P P P P P P P P P P I
P I P P P P P P P I P P P P P P P I
Static scene
Activities
P P P
P I P P P P P P P I P P P P P P P I
By dynamically prolonging the intervals for I-frames insertion to up to 10 seconds, the bit rates required
for streaming a video can be tremendously reduced. When streaming a video of a static scene,
the Dynamic Intra frame feature can save up to 53% of bandwidth. The amount of bandwidth thus
saved is also determined by the activities in the field of view. If activities occur in the scene, firmware
automatically shortens the I-frame insertion intervals in order to maintain image quality. In the low light
or night conditions, the P-frames can have a larger size due to the noises, and hence the bandwidth
saving effect is also reduced.
Streaming a typical 2MP scene normally requires 3~4Mb/s of bandwidth. With the Dynamic Intra frame
function, the bandwidth for streaming a medium-traffic scene can be reduced to 2~3Mb/s, and during
the no-traffic period of time, down to 500kb/s.
H.264/265 Frame Types
Dynamic Intra Frame w/
static scenes
Dynamic Intra Frame w/
activities in scenes
Smart stream II
