User Guide

Chapter 2 Preparing Assets 69
There are some additional considerations when creating a mixed-angle track:
• Within a track, you can use markers to define multiple sections to use additional
angles, but each section must have the same number of streams. For example, you
cannot have one section early in the track with two alternate streams and a section
later in the track with three alternate streams—both sections must have either two
or three streams.
• Each alternate angle section can be a different length, but all streams within a
section must be the same length. For example, you can have one mixed-angle
section early in the track that is 10 seconds long and a second mixed-angle section
that is 20 seconds long. All alternate streams in the first mixed-angle section must be
10 seconds long; all alternate streams in the second mixed-angle section must be 20
seconds long.
• You cannot use still images in the V2 through V9 streams. You can use still images in
the V1 stream as long as they are outside of the mixed-angle areas (places where
video is present in the V2 through V9 streams).
Requirements for MPEG Streams in Multi- and Mixed-Angle Video
The embedded MPEG encoder produces streams that meet the criteria for multi- and
mixed-angle use:
• With multi-angle tracks, all streams must be the same length. With mixed-angle
tracks, all alternate streams in each mixed-angle section must be the same length.
• All streams must have the same resolution and frame rate.
• The length and pattern of GOPs (Group of Pictures) must be the same for all streams
(angles). If you are not using the embedded MPEG encoder, use an encoder that
allows you to turn scene detection off.
• All GOPs should be closed. You will not be able to cleanly switch between the
streams if you use open GOPs.
Using Final Cut Pro and Compressor
In addition to the chapter and compression markers you can manually add to a video
clip in Final Cut Pro and Final Cut Express, compression markers are automatically
added at each edit point.
The manually added chapter and compression markers (also known as named markers)
are processed by the embedded MPEG encoder and by Compressor. Be sure to add
identically placed chapter and compression markers to each video clip you intend to
use in a mixed- or multi-angle track.
The embedded MPEG encoder ignores the automatic compression markers, since they
can alter the GOP structure and make the clip unusable for mixed- and multi-angle tracks.