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Appendix: MPEG Encoder Settings 353
altered in any way; only hard cuts (without fades) are permitted. These won't be
executed precisely to the frame, but will rather take place at the next GOP borders.
For this reason, cuts should be set somewhat more generously.
To burn DVDs in original 5.1 Surround Sound (Dolby Digital Audio) without having to
re-encode, this option has to be activated.
Allows you to rip the necessary settings from an existing MPEG file. This can be
useful if you want to merge MPEG files together without re-rendering via Smart
Rendering.
Video settings
Frame rate: PAL requires 25 frames/sec, NTSC 29.97 frames/sec. Please note:
encoding NTSC material as PAL or vice versa may be possible; however, it will result
in jittery images.
Aspect ratio: Lets you set the image side or pixel ratio. With MPEG-2 the image
format is displayed as image ratio; correspondingly there is 1:1 (square screen, not
recommended), 4:3 (regular video), 16:9 (widescreen) and 2.21:1 (cinemascope). This
applies irrespectively of the selected video format.
For MPEG-1 the pixel format is set; the options here are 1:1, CCIR601 (represents
normal 4:3 video) for 625 lines = PAL and 525 lines = NTSC and the same for 16:9.
The option Auto is set as default. Here you can adjust the Movie settings (view page
288) accordingly.
Resolution: Width and h
eight of the video corresponds with the settings in the export
dialog.
GOP structure: Here you can change the settings of the GOP (view page 359)
seque
nce, i.e. the number of P frames and B frames per I frame within a GOP. Please
note that the total length of the GOP must not exceed 15 frames, which corresponds
to the default setting (1 I frame + 4 P frames + 5*2 B frames = 15 frames).
However, you can reduce the length of the GOP sequence (while compromising the
image quality at the same bit rate). This speeds up the encoding process considerably
as the motion estimation while encoding P and B frames requires high CPU
performance. The speed of decoding, i.e. playback, is also increased.
If I frame is set to 1, each frame is an I frame. If the value is set higher, the setting
describes the total length of the GOP.
Auto GOP: Closed GOPs do not contain relations to frames from subsequent GOPs.
MPEGs where all GOPs are closed, make MPEG editing easier as the I frames only can