Specifications

Rate Control Mode

The Rate Control Mode helps determine the video quality produced by the encoder. The Verint Rate

Control Mode, along with the Target Bit Rate, Target Frame Rate, and Minimum and Maximum

Quantizers provide maximum flexibility in configuring Nextiva encoders.

• The default value, which is most frequently used, is CBR. In this mode, the encoder will do

everything to keep the bit rate equal or under the target. To do that, it will adjust the

quantizer level within the minimum and maximum ranges that have been set. Once the

Maximum Quantizer (minimum quality) level has been reached, the encoder will reduce video

frame rate.

• If you want to maintain frame rate, no matter what adjustments to bit rate might be

necessary, set the Rate Control Mode to CFR. The encoder will not increase bit rate over the

target until the Maximum Quantizer level has been reached.

• If you want a true variable bit rate mode, wherein you set the video quality and the bit rate

can vary, you must set the Rate Control Mode to CFR and set the Minimum and Maximum

Quantizers to the same value.

• The Constant Storage Rate (CSR) mode (formerly called the Constant Nextiva Rate, or CNR)

works much like the CBR mode, with one difference. With CSR, if the bit rate is lower than the

target for a certain period of time, the bit rate can then be raised above the target value. The

CSR mode is useful in cases where there is no movement for long periods of time (requiring a

very low bit rate), then a lot of fast movement (requiring a high bit rate). This mode must be

used with Nextiva enterprise video management software to make optimal use of storage

capacity.

• The Advanced Constant Bit Rate (ACBR) mode is similar to CBR in that it maintains the target

bit rate, but it is more precise. As a result, frame rate may decrease and video quality may be

compromised. This mode is preferred for high-frame-rate contexts where it is desirable to

maintain the bit rate.

Multiplying Factor for Storage

If the Rate Control Mode is set to CSR (see above), this parameter specifies the amount by which the

bit rate can exceed the target. The value is expressed as a percentage of the Target Bit Rate. For

example, if the Target Bit Rate is set to 4,000, and the Multiplying Factor for Storage is set to 125, the

actual bit rate, over a certain period of time, could go as high as 5,000 (125% of 4,000).

Maximum Output Rate per Stream (Traffic Shaper)

This setting, under the Test and Debug Menu, should generally not be modified. But if your network

equipment does not support data rate peaks, which occur when there is no memory in the switches,

routers, etc., you might want to shape the video traffic. The Maximum Output Rate per Stream will

shape the traffic to avoid sending to many packets within a few milliseconds. You can set this value

from 10 to 50,000 Kbits per second. The shaper is not related to the Codec Rate Control (CRC), and

the value should be at least 20% over the Target Bit Rate.