Altera Video and Image Processing Suite - Manual (Page 21)

IP Core Stall Behavior Error Recovery
Chroma
Resampler
All modes stall for a few cycles between
frames and between lines.
Latency from input to output varies
depending on the operation mode of the IP
core.
• 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—corresponding to one line
of 4:2:0 data
• The quantities of data input and output
are not equal because this is a rate-
changing function.
• Always produces the same number of
lines that it accepts—but the number of
samples in each line varies according to
the subsampling pattern used.
When not stalled, 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.
• Receiving an early
endofpacket
signal—the IP core stalls its input but
continues writing data until it has
sent an entire frame.
• Not receiving an
endofpacket
signal
at the end of a frame—the IP core
discards data until it finds end-of-
packet.
Clipper/
Clipper II
• Stalls for a few cycles between lines and
between frames.
• Internal latency is less than 10 cycles.
• During the processing of a line, it reads
continuously but only writes when
inside the active picture area as defined
by the clipping window.
• Receiving an early
endofpacket
signal—the IP core stalls its input but
continues writing data until it has
sent an entire frame.
• Not receiving an
endofpacket
signal
at the end of a frame—the IP core
discards data until it finds end of
packet.
Clocked Video
Input/
Clocked Video
Input II
• Dictated by incoming video.
• If its output FIFO is empty, during
horizontal and vertical blanking periods
the IP core does not produce any video
data.
If an overflow is caused by a
downstream core failing to receive data
at the rate of the incoming video, the
Clocked Video Input sends an
endofpacket
signal and restart sending
video data at the start of the next frame
or field.
UG-VIPSUITE
2015.05.04
Stall Behavior and Error Recovery 1-15
Video and Image Processing Suite Overview Altera Corporation
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