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be edited alone if the GOP is closed. Auto GOP closes GOPs at scene changes,
whereby two different and complex procedures ("fast" and "VCSD") are used.
Bit rate mode
In "constant bit rate" mode a bit rate that constantly remains the same is used. With a
constant bit rate the full power of MPEG compression can not be used properly as
bandwidth for non-moving scenes is lost.
"Variable bit rate" mode attempts to adjust the available storage space to the
requirements of the video you want to encode. The actual bit rate fluctuates around a
mean value. During calm sections of the video it may drop to a minimum value, if
there are movements in the scene it may rise to the maximum value. There are two
different regulation processes (mode 1 and mode 128).
Advanced video settings
MPEG profile and level: The MPEG-2 standard defines various "profiles" and "levels".
For creating DVDs you can use the "Main profile & Main level". The high profile adds
additional properties to the data stream, such as the option of displaying an image at
a reduced resolution for restricted transmission quality (SNR scalable profile) or
locally scaled, for instance an HDTV data stream on a standard TV set). The 4:2:2
profile is used if the image data is to be encoded for alternative chroma scanning
(view page 358). However, these profiles are only sup
ported by very few encoders,
mainly for professional use.
The different levels define the restrictions to the image resolution and the maximum
data rate. Low level can only reach a reduced resolution (352 x 2888 = CIF), high
level or High -1440 enables encoding in HDTV format.
Estimate movement: These parameters are controlled by the quality controller (see
General Settings).
Other
Noise sensitivity: This factor defines how sensitive the encoder will react to noise in
the source material. If your source material only contains little noise (digital
recordings, computer animations or already de-noised by video cleaning), you don't
have to change the default value 4, or you can even reduce it in order to increase the
quality further.
However, if you want to encode noisy material, a factor that is too low will
considerably increase the encoding time without producing higher quality. For an
unedited analog video you can increase the factor to 8-14.