User guide

109
Using Apple Compressor
encode these transitions as I-frames. This results in multi-pass quality in a
single pass. This option can be useful for creating higher quality video at a
given data rate
. It’s especially useful when encoding video with many
scene changes and targeting a low data rate.
7 Under Video Compression, specify the compression settings for your
encoded video:
$ Algorithm Select the entropy coding method to be used during
compression:
• CABAC Uses the CABAC coding method, and defines the video
stream as H.264 Main profile.
• CAVLC Uses the CAVLC coding method, and defines the video
stream as H.264 Baseline profile when
Distance between P frames
is set to 1. Otherwise, the video stream is defined as H.264 Main
profile. This method is not supported when encoding to a frame size
that has a width greater than 720.
$ Compression type Select from the following compression types:
• Variable data rate Video is compressed at varying data rates based
on the complexity of the video and your specified minimum and
maximum data rates. The Matrox MAX H.264 codec analyzes and
encodes each frame to deliver the highest possible quality at your target
data rate.
• Constant data rate Video is compressed at your specified target
data rate, which is useful when you need to limit or predict the size of
your video file. However, if your video is very complex (such as scenes
with many colors, sharp edges, or transitions), you’ll need to specify a
high target data rate to avoid having frames of blocky video in your file.
• Constant quality Delivers your desired quality on each frame with
no regard to data rate.
Remarks
$ When using Constant quality, the entropy encoding algorithm must be
set to CABAC.
$ Variable data rate and Constant quality compression types are not
recommended for delivering H.264 files for Blu-ray.
8 Specify the settings associated with your selected compression type:
$ Target data rate (Variable/Constant data rate only) Enter the target
data rate, in
Mb/s or Kb/s, for your encoded video. The higher the target
data rate you specify, the better the video quality will be.
$ Minimum/Maximum data rate (Variable data rate only) If locked
() to the
Target data rate, the minimum and maximum data rates are