Adobe Premiere Elements 12 - Manual (Page 282)

N Frames
Closed GOP Every
Automatic GOP Placement
Audio Format
Audio Codec
Sample Rate
Sample Type
Channels
Interleave
Bitrate
Bitrate Mode
This option is available only for MPEG formats.
Specifies the number of frames between I frames (intra-frames). This value must be a multiple of the M frames value. This option is
available only for MPEG formats.
Specifies the frequency of each Closed Group of Pictures (Closed GOP), which can’t reference frames outside of the closed
GOP. A GOP consists of a sequence of I, B, and P frames. (This option is available when you choose either of the Multimedia Compatible presets
(MPEG1 Multimedia Compatible or MPEG2 Multimedia Compatible) from the Export MPEG dialog box, and then click Advanced.)
When selected, sets the placement of Group of Pictures (GOP) automatically. (This option is available when you
choose either of the MPEG Multimedia Compatible presets from the Export MPEG dialog box, and then click Advanced.)
note: MPEG-1 and MPEG-2 formats include numerous advanced options not listed here. In most cases, selecting a format or preset designed for
your target output sets the appropriate options automatically. For detailed information on options not listed, consult the industry specifications for
the MPEG-1 and MPEG-2 formats.
Audio settings
The following options are available in the Audio panel of the Export Settings dialog box (you see these when you share a project using the
Computer or Mobile Phones And Players options). Not all options are available for all presets.
Specifies the type of audio output, such as Dolby Digital or MP3, and may determine which audio codec is used.
Specifies the codec for Premiere Elements to apply when compressing audio. The codecs available depend on the file type you
specified in the General panel in the Export Settings dialog box. Some file types and capture cards support only uncompressed audio, which has
the highest quality, but uses more disk space. Check with your capture card’s documentation before choosing an audio codec.
Specifies the rate for export. Choose a higher rate for better audio quality in an exported file, or choose a lower rate to reduce
processing time and disk-space requirements. CD quality is 44.1 kHz. Resampling, setting a different rate than the original audio, also requires
additional processing time. Avoid resampling by capturing audio at the final rate.
Specifies the bit depth for export. Choose a higher bit depth and stereo for better quality, or choose a lower bit depth and mono to
reduce processing time and disk-space requirements. CD quality is 16-bit stereo.
Specifies how many audio channels are in the exported file. By default, stereo provides two channels of audio; mono provides one. If
you choose to export a stereo track as mono, the audio will be down mixed.
Specifies how often audio information is inserted among the video frames in the exported file. See your capture card documentation for
the recommended setting. A value of 1 frame means that when a frame is played back, the audio for the duration of that frame is loaded into RAM
so that it can play until the next frame appears. If the audio breaks up when playing, the interleave value may be causing the computer to process
audio more frequently than it can handle. Increasing the value lets Premiere Elements store longer audio segments that need to be processed less
often, although higher interleave values require more RAM. Most current hard disks operate best with 1/2- to 1-second interleaves.
Specifies the number of megabits per second you want the encoded file to have. Generally, higher bitrates increase both quality and file
size. This option is available for Dolby Digital Stereo, MPEG, and some Windows Media Audio codecs.
note: Options not documented here are specific to the selected format. For detailed information, consult the industry specifications for the selected
format.
Specifies whether the codec achieves a constant or variable bitrate in the exported file. Constant keeps the data rate of the
exported file constant within a fixed limit you specify. Since the complex sections are held to the same bitrate as the simple, they are more likely to
show the quality-degrading artifacts of compression. Variable allows the exported file’s data rate to vary within a range you specify, allocating
higher bitrates, and therefore less compression, to the more complex sections and lower bitrates to the less complex.
In general, a frame is complex and more difficult to compress efficiently if it contains great detail, or if it significantly differs from surrounding
frames, as it would in a scene containing motion.
note: When comparing CBR and VBR files of the same content and file size, 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
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