User guide

Table Of Contents
8–4 Chapter 8: Chroma Resampler MegaCore Function
Functional Description
Video and Image Processing Suite January 2013 Altera Corporation
User Guide
1 All input data samples must be in unsigned format. If the number of bits per pixel per
color plane is N, this means that each sample consists of N bits of data which are
interpreted as an unsigned binary number in the range [0, 2
N
– 1]. All output data
samples are also in the same unsigned format.
1 For more information about how non-video packets are transferred, refer to “Packet
Propagation” on page 3–11.
Avalon-ST Video Protocol Parameters
The Chroma Resampler MegaCore function can process streams of pixel data of the
types listed in Table 81.
Stall Behavior and Error Recovery
All modes of the Chroma Resampler MegaCore function stall for a few cycles between
frames and between lines. Latency from input to output varies depending on the
operation mode of the Chroma Resampler MegaCore function. The only modes with
latency of more than a few cycles are 4:2:0 to 4:2:2 and 4:2:0 to 4:4:4. These modes have
a latency corresponding to one line of 4:2:0 data.
Because this is a rate-changing function, the quantities of data input and output are
not equal. The Chroma Resampler MegaCore function always outputs the same
number of lines that it inputs. However the number of samples in each line varies
according to the subsampling pattern used.
When not stalled, the Chroma Resampler always processes one sample from the more
fully sampled side on each clock cycle. For example, the subsampled side pauses for
one third of the clock cycles in the 4:2:2 case or half of the clock cycles in the 4:2:0 case.
Table 8–1. Chroma Resampler Avalon-ST Video Protocol Parameters
Parameter Value
Frame Width
Maximum frame width is specified in the parameter editor, the actual value is read from control
packets.
Frame Height
Maximum frame height is specified in the parameter editor, the actual value is read from control
packets.
Interlaced /
Progressive
Progressive.
Bits per Color Sample Number of bits per color sample selected in the parameter editor.
Color Pattern
For 4:4:4 sequential data: For 4:2:2 sequential data:
For 4:2:0 sequential data: For 4:2:2 parallel data:
For 4:4:4 parallel data: For 4:2:0 parallel data:
CrCb Y
CrCb YY
Cb
Cr
Y Y
Cb Cr
YY
Y
Cb
Cr
CrCb
Y
Y