VBrick 9000 Admin Manual page 73

Field
Rate Control Setting 1: Lowest Latency – 5: Best Quality. Default = 5. This parameter lets
Profile
Entropy Coding
VBrick 9000 Encoder Admin Guide
Description
you trade off video quality versus the latency imposed by the
encoder. A higher value provides better quality but more latency; a
lower value provides less latency with a loss of quality. This
parameter lets you trade-off video quality with how tightly rate
control is imposed. A larger number increases the number of frames
over which the target number of bits can be distributed. This means
that the average bit rate, measured over small periods of time, can
fluctuate more around the specified target bit rate. A smaller number
will reduce the fluctuations around the target bit rate but will also
reduce the ability of rate control to apply the bits to scenes which
might be visually optimized by their application. In addition, when
using the transport mode (see Transport Stream Settings)
Custom
and attempting to tune for lowest possible latency (minimal
), it is useful to minimize the bit rate fluctuations by using a
Gap
smaller value. In bandwidth-restricted networks with little tolerance for bit
rate fluctuations, or when tuning aggressively for minimum delay, a smaller
value is recommended; otherwise, use a larger value or the default.
The profile defines the subset of bit stream features in an H.264
stream, including color reproduction and video compression.
• Baseline: Default. A simple profile with a low compression ratio.
The baseline profile uses more bits to compress quality video
than the other profiles. Use the baseline profile in applications
with limited scene changes and minimal motion.
• Main: An intermediate profile with a medium compression ratio.
This profile uses fewer bits to compress video than the baseline
profile; however, it uses more bits than the High profile.
• High: A complex profile with a high compression ratio. This is
the primary profile for high-definition applications. For example
Blu-ray and HD-DVD use this profile.
• CAVLC – Default. Context-adaptive variable-length coding is an
alternative to CABAC. CAVLC requires considerably less
processing than CABAC but does not compress the data as
effectively. CAVLC is supported in all H.264 profiles, unlike
CABAC which is supported in Baseline and Extended profiles
only.
• CABAC– Context-adaptive binary arithmetic coding is a lossless
compression. It is one of the primary advantages of the H.264/
AVC encoding scheme. CABAC is only supported in Main and
higher profiles and is CPU-intensive. As a result, CAVLC (a lower
efficiency method) is used to increase performance on slower
playback devices.
Encoder Configuration
PTS-PCR
65