Encoding Video for Multi-Angle Tracks

DVD Studio Pro supports multi-angle and mixed-angle video. With multi-angle video, a track can contain up to eight alternate video streams that last the entire length of the main stream (for a total of nine video streams per track). With mixed-angle video, the alternate streams do not last the entire length of the main stream, so you can have alternate streams in only those locations where they are needed, saving disc space. In either case, the viewer can switch among angles using the Angle button on the remote control.

Because different MPEG encoders can produce slightly different GOP structures, you should use the same encoder for all streams.

Note: Switching angles while playing a DVD affects only the video playback. The audio remains on the currently selected stream.

Considerations for Mixed-Angle Tracks

Mixed-angle tracks provide the possibility of interesting playback scenarios. The illustration below shows a track that has two sections with three alternate angles, with playback set to angle 3.

Figure. Example of a mixed-angle video stream playing the third angle.

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 integrated 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 integrated 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 integrated MPEG encoder and by Compressor when used directly. 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 integrated MPEG encoder ignores the automatic compression markers, because they can alter the GOP structure and make the clip unusable for mixed- and multi-angle tracks.

You can either set Compressor to process the automatic compression markers or ignore them. The Extras pane of the Compressor MPEG-2 presets includes an “Include chapter markers only” checkbox. Select the checkbox to force Compressor to ignore the automatic compression markers if you are encoding clips for use in a mixed- or multi-angle track. See Using Compression Markers to Improve the MPEG Encode for more information about compression markers.

Maximum Bit Rates for Multi- and Mixed-Angle Tracks

The maximum bit rate for a multi- or mixed-angle track is different from other tracks. Due to the way the DVD specification requires video streams to be multiplexed together, the number of video streams determines the maximum video bit rate you can use. Following is a list of maximum combined bit rates (highest bit rate video stream + all audio streams + all subtitle streams) you can use for each multi- and mixed-angle track.

Important: When calculating the combined bit rate for a track, you only need to add in the bit rate of one video stream, but it needs to be the stream with the highest bit rate.

SD Projects
  • 5 angles or fewer: 8 Mbps maximum for the track’s combined bit rate
  • 6–8 angles: 7.5 Mbps maximum for the track’s combined bit rate
  • 9 angles: 7 Mbps maximum for the track’s combined bit rate
HD Projects
  • 2 to 9 angles: 24 Mbps maximum for the track’s combined bit rate

    Note: 1080i HDV video uses a bit rate of 25 Mbps, which is higher than the maximum allowable multi-angle bit rate. 720p HDV video uses a bit rate of 19 Mbps, which, depending on the number and type of audio and subtitle streams, can be used in a multi-angle project.