ADS Technologies USBAV-708 INSTANT VIDEOMPX, Руководство пользователя

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The
Guide
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It soon becomes clear that higher
quantizers introduce larger errors
due to rounding before inverse
quantization; thus when encoding
lower frame quantizers lead to
higher quality images.
Plotting results from the tables
with respect to the original series
illustrates lower quantizers recreating a more accurate signal.
Although lower quantizers give higher quality images they also produce
larger file sizes. This is because the range of results encompassed by
lower quantizers is larger than that of higher quantizers.
In the tables, results of data quantized at Q=3 could potentially include
any value of interval 3 (
0, 3, 6, 9…) . Data quantized at Q=5 has a
larger interval ( 0, 5, 10, 15…) . Within a fixed range, I.e. 1 - 100, there
are less possible values for Q=5 results than for Q=3 results. This
leads to better compression for Q=5, and higher quantizers in general.
Under most modes the DivX encoder will fully manage control of the
quantizer for you, although it is possible to specify a quantizer for
encoding if you want to.
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Original Q=3 Q=5