User guide

Table Of Contents
Chapter 15: Deinterlacer MegaCore Function 15–9
Functional Description
January 2013 Altera Corporation Video and Image Processing Suite
User Guide
When you select the weave algorithm, the MegaCore function may stall for longer
than the usual periods between each output row of the image. Stalls of up to 45 clock
cycles are possible due to the time taken for internal processing in between lines.
When you select the motion-adaptive algorithm, the Deinterlacer may stall up to 90
clock cycles.
Error Recovery
An error condition occurs if an
endofpacket
signal is received too early or too late
relative to the field dimensions contained in the last control packet processed. In all its
configurations, the Deinterlacer discards extra data if the
endofpacket
signal is
received too late.
If an early
endofpacket
signal is received when the Deinterlacer is configured for no
buffering, the MegaCore function interrupts its processing within one or two lines
sending undefined pixels, before propagating the
endofpacket
signal.
If an early
endofpacket
signal is received when the Deinterlacer is configured to
buffer data in external memory, the input side of the MegaCore function stops
processing input pixels. It is then ready to process the next frame after writing
undefined pixels for the remainder of the current line into external RAM. The output
side of the Deinterlacer assumes that incomplete fields have been fully received and
pads the incomplete fields to build a frame, using the undefined content of the
memory.
1 For more information about the stall behavior and error recovery, refer to “Stall
Behavior and Error Recovery” on page 1–3.
Latency
Table 152 lists the approximate latency from the video data input to the video data
output for typical usage modes of the Deinterlacer MegaCore function. You can use
this table to predict the approximate latency between the input and the output of your
video processing pipeline.
The latency is described using one or more of the following measures:
the number of progressive frames
the number of interlaced fields
the number of lines when less than a field of latency
a small number of cycles O (cycles)