Cisco D9054 Installation And Operation Manual page 98

Setting Up the H.264 Video Encoder,
5. If the High Profile license is installed, and High Profile is selected as the Video
Encoding profile as shown below, all of the High Profile Features should be
enabled (checked) for optimal compression efficiency. Individual features
should only be disabled if the decoder(s) do not support the particular feature.
Note: For this application you must be using decoders downstream which
support High Profile functionality to make use of these features such as the
D9887 HDTV Modular Receiver.
Each of the High Profile settings are described below:
Intra 8x8 Prediction - selects Intra 8x8 prediction mode and 8x8 transform for
Intra-coded macroblocks in addition to Intra 16x16 and 4x4 prediction modes in
Main Profile. This increases compression efficiency.
Inter 8x8 Transform - selects 8x8 transform for Inter-coded macroblocks in
addition to 4x4 transform in Main Profile. This increases compression efficiency.
QP scaling - selects different quantization step sizes for each frequency. This
improves subjective quality at lower bit rates or for stressed content.
6. Select Full, 3/4, 2/3 or 1/2 Sub-sampling.
Subsampling decreases the resolution of the source material in order to lower
the amount of data to be encoded. 2/3 horizontal resolution is not supported for
720p.
7. Enable Dynamic GOP. Dynamic GOP should always be enabled for best video
quality.
Dynamic GOP adds to end-to-end delay. If lower end-to-end delay is more
important than video quality, then Dynamic GOP should be turned off
(disabled).
When Dynamic GOP is on (the default is off), the encoder selects between two
hierarchical GOP structures, one with 3 B-pictures and the other with 15 B-
pictures. The selection is automatically based on video content (scene's spatio-
temporal complexity).
When using Dynamic GOP, the GOP Length must be a multiple of 16 (i.e., 16,
32, 48, etc).
8. Type the GOP Length.
The GOP length must be in the range from 1 to 255.
5-14 D9054 HDTV Encoder Intstallation and Operation Guide
Continued
4038938 Rev A