Adobe Media Encoder CC - Manual (Page 54)

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Encoding and exporting
Last updated 12/15/2014
Export As Sequence For still-image export, select this option to export as a sequentially numbered series of still-image
files.
Header Type Specifies SMPTE/DPX or Cineon header.
Depth Color depth in bits per pixel.
Encoding Passes Number of times the encoder will analyze the clip before encoding. Multiple passes increase the time
it takes to encode the file, but generally result in more efficient compression and higher image quality.
M Frames Number of B frames (bi-directional frames) between consecutive I frames (intra-frames) and P frames
(predicted frames).
N Frames Number of frames between I frames (intra-frames). This value must be a multiple of the M frames value.
Closed GOP Every Frequency of each closed group of pictures (closed GOP), which cannot reference frames outside of
the closed GOP. A GOP consists of a sequence of I, B, and P frames. (This option is available if you choose MPEG-2 as
the format.)
Bitrate Number of megabits per second. Different formats present different bitrate options. The minimum bitrate
differs according to the format. For example, for MPEG-2 DVD, the minimum bitrate is 1.5 Mbps.
Bitrate Mode or Bitrate Encoding Specifies the type of variable bit the codec produces in the exported file:
VBR, 1 Pass Variable bitrate, with the encoder making a single pass through the file from beginning to end. Single-pass
encoding takes less time than dual-pass encoding, but doesn’t achieve the same quality in the output.
VBR, 2 Pass Variable bitrate, with the encoder making two passes through the file, from beginning to end, and then
from end to beginning. The second pass prolongs the process, but it ensures greater encoding efficiency, and often a
higher-quality output.
Note: When comparing CBR and VBR files of the same content and file size, you can make the following generalizations:
A CBR file may play back more reliably over a wider range of systems, because a fixed data rate is less demanding on a
media player and computer processor. However, a VBR file tends to have a higher image quality, because VBR tailors the
amount of compression to the image content.
Bitrate Level (H.264 Blu-ray, and MPEG-2 Blu-ray formats only) When the Bitrate level is set to Custom, the output
bitrate can be changed to any value. When the Bitrate Level is set to High, Medium, or Low, the bitrate is set
automatically based on frame dimensions as a read-only value and cannot be changed. Adobe Media Encoder has
default presets for the formats which have the Bitrate Level set to automatic.
Key Frame Interval [Seconds] or Set Key Frame Distance (Frames) Number of frames after which the codec will create a
key frame when exporting video. (See Key frames .)
Optimize Stills or Expand Stills Select this option to use still images efficiently in exported video files. For example, if a
still image has a duration of 2 seconds in a project set to 30 fps, Adobe Premiere Pro creates one 2-second frame instead
of 60 frames at 1/30 of a second each. Selecting this option can save disk space for sequences and clips containing still
images. Deselect this option only if the exported video file exhibits playback problems when displaying the still images.
Multiplexer export settings
The Multiplexer preset options (sometimes called Format) control how MPEG video and audio data are merged into a
single stream. The exact options available depend on the MPEG format you choose.
When you choose the MPEG-2 format, all Multiplexer options provided by the MPEG standard are available for
manual control. In most cases, it’s better to select an MPEG preset specifically targeted to your output medium (such
as MPEG-2 DVD).