ADS Technologies USBAV-708 INSTANT VIDEOMPX, Руководство пользователя

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As discussed in Forward-General concepts-Quantizers , DivX uses quantizers to
control the picture quality in each frame. Lower quantizers equate to higher
quality and bit-spend, while higher quantizers equate to lower quality and bit-
spend.
The aim of the EKG application is to control the
modulation value associated with
each frame in the multipass log file. This modulation value actually manipulates
the frame quantizer chosen by the rate-control by acting as a co-efficient.
Frame quantizer = Modulation * Quantizer
Thus if the rate-control would normally encode a particular frame at Q=6 but a
modulation of 2.0 was specified the frame would instead be encoded at Q=12. A
modulation of 1.0 would leave the original quantizer unchanged (1.0 x Q = Q),
and a modulation of 0.5 would halve the quantizer so that the frame would be
encoded at Q=3.
Notice that the EKG can not show the actual quantizer for any particular frame as
this is a decision made on-the-fly as video is encoded by the rate control.
Modulation allows you to manipulate quality in terms of proportionality, not in
terms of fixed quantizers.
Also notice that the relationship between quantizer value and quality is inverse, a
lower quantizer gives rise to higher quality. Therefore, a modulation of 2.0 is the
equivalent of 50% quality, while a modulation of 0.5 is the equivalent of 200%
quality.
How the EKG works