4.1.2

Chapter 4 Advanced adjustments 38
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Format: Use the pop-up menu to set the stream type for the output le. There are three options:
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Program Stream: This stream type contains only one MPEG-2 content channel and its
associated audio. Program streams require an error-free delivery method and are primarily
used for storage or processing within a computer.
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Elementary Stream: This stream type contains only one MPEG-2 content channel and no
audio. When you select this option, you should also set the “Stream usage” property.
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Transport Stream: This stream type can contain several MPEG-2 content channels and
associated audio. All the channels are multiplexed together, allowing the receiver to choose
which to play back. Compressor supports creating single-channel transport streams that can
also include associated audio. Transport streams can also recover from interruptions during
playback, making them ideally suited for broadcast and streaming applications where noise
or network congestion can lead to interruptions.
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Stream usage: Use this pop-up menu to specify the MPEG-2 transcoding output. Compressor
modies the available properties based on the option you choose:
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Generic: This option allows you complete access to all the MPEG-2 properties. This is the
only option that supports the MPEG-2 640 x 480 video format in addition to the standard-
denition (SD) and high-denition (HD) video formats. It’s also the only option that supports
creating transport and program streams. It supports the complete bit rate range of 2.0 Mbps
to 40.0 Mbps.
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DVD: This option restricts the encoding properties to those allowed by the SD DVD
specication. These include the NTSC and PAL video formats and a bit rate range of 2.0 Mbps
to 9.0 Mbps.
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Blu-ray: This option restricts the encoding properties to those allowed by Blu-ray video discs.
These include the SD and HD video formats and a bit rate range of 10.0 Mbps to 40.0 Mbps.
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Add Apple metadata: Select this checkbox to have Compressor parse specic MPEG-2 authoring
information during the transcoding process and provide it in the output le. The resulting le
will be read faster by other applications.
•
Include chapter markers only: Select this checkbox to include chapter markers, but not
unnamed compression markers, in MPEG-2 output. When this checkbox is deselected, all
markers are included in the output le. For more information about chapter markers, see Add
markers on page 80.
Retiming
This section contains one property:
•
Set duration to: Sets the processing algorithm used to adjust the frame rate during transcoding.
Select one of the following options:
•
[Percentage] of source: Modies the output clip’s speed by a percentage of the source clip’s
speed. Enter a value in the percentage eld or choose a preset value from the adjacent
pop-up menu (with a downward arrow).
•
[Total duration]: Sets the duration of the clip. Enter a timecode duration in the eld or click
the arrows to increase or decrease the time.
•
So source frames play at [frame rate] fps: Nondestructively changes the playback speed of the
clip, without discarding frames or creating new frames. This setting has no eect unless the
“Frame rate” value in the Video inspector is dierent than the source le’s frame rate. For
example, if you add a 10-second source le with a frame rate of 24 fps to Compressor, set the
“Frame rate” property in the Video inspector to 25 fps, and then select “So source frames play
at 25 fps” in the General inspector, the duration of the transcoded clip (at 25 fps) is 9 seconds
and 15 frames.
For more information, see Retime video and audio on page 69.
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