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Video Scaler v4.0 User Guide
UG805 March 1, 2011
Chapter 6:
Control Interface
Hence, up-scaling is achieved using a shrink-factor value less than one. Down-scaling is
achieved with a shrink-factor greater than one.
You may wish to work this calculation backwards. For a desired scale-factor, you may wish
to calculate the output size or the input size. This is application-dependent. Smooth
zoom/shrink applications may take advantage of this approach, coupled with usage of the
following start-phase controls described below.
The allowed range of values on these parameters is 1/12 to 12: (0x015555 to 0xC00000).
•
num_h_phases
,
num_v_phases
Although you must specify the maximum number of phases (
max_phases
) that the core
supports in the CORE Generator GUI, it is not necessary to run the core with a filter that
has that many phases. Under some scaling conditions, you may want a large number of
phases, but under others you may need only a few, or even only one. Non power-of-two
numbers of phases are supported.
•
coef_wr_addr
,
h_coeff_set
,
v_coeff_set
In GPP and pCore interfaces, you may load coefficients. The scaler can store up to
max_coef_sets
coefficient sets internally.
coef_wr_addr
sets the set location of the set
to which you intend to write. The set may subsequently be used by controlling the
h_coeff_set
and
v_coeff_set
values.
•
start_hpa_y
,
start_hpa_c
,
start_vpa_y
,
start_vpa_c
These are the start-phase controls. Internally to the core, the scaler accumulates the 24-bit
shrink-factor (hsf, vsf) to determine phase and filter aperture. These four values allow you
to preset the fractional part of the accumulations horizontally (hpa) and vertically (vpa) for
luma (y) and chroma (c).
When dealing with 4:2:2, luma and chroma are always vertically cosited. Hence the
start_vpa_c
value is ignored.
Usage of these parameters is important for scaling interlaced formats cleanly. On
successive input fields, the
start_vpa_y
value needs to be modified.
Also, when the desired result is a smooth shrink or zoom over a period of time, you may
get better results by changing these parameters for each frame.
The allowed range of values on these parameters is -0.99 to 0.99: (0x100001 to 0x0FFFFF).
The default value for these parameters is 0.
•
control
The control register contains only two active bits. The default value for the control register
during continuous operation is “0x3.”
•
bit 0
is a general purpose enable. Activated/deactivated on a
vblank_in
basis, a
value of 0 disables the scaler output.
•
bit 1
enables values on the other register inputs to become internally active on a
vblank_in
basis. A value of 0 prevents the active internal values from being
changed.
Содержание LogiCORE IP
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Страница 14: ...14 www xilinx com Video Scaler v4 0 User Guide UG805 March 1 2011 Preface About This Guide...
Страница 18: ...18 www xilinx com Video Scaler v4 0 User Guide UG805 March 1 2011 Chapter 1 Introduction...
Страница 20: ...20 www xilinx com Video Scaler v4 0 User Guide UG805 March 1 2011 Chapter 2 Overview...
Страница 70: ...70 www xilinx com Video Scaler v4 0 User Guide UG805 March 1 2011 Chapter 9 Performance...
Страница 74: ...74 www xilinx com Video Scaler v4 0 User Guide UG805 March 1 2011 Appendix A Use Cases...
Страница 92: ...92 www xilinx com Video Scaler v4 0 User Guide UG805 March 1 2011 Appendix B Programmer Guide...