IPSR-VIDEO Altera, IPSR-VIDEO Datasheet - Page 153

• Manufacturer Part Number: IPSR-VIDEO
• Description: RENEWAL Of IPS-VIDEO
• Manufacturer: Altera
• Series: IP Suitesr

Specifications of IPSR-VIDEO

• Software Application: IP CORE, SUITES
• Supported Families: Arria GX, Cyclone II, HardCopy II, Stratix II
• Features: Common Avalon Streaming (Avalon-St) Interface And Avalon-St Video Protocol
• Core Architecture: FPGA
• Core Sub-architecture: Arria, Cyclone, Stratix
• Rohs Compliant: NA
• Lead Free Status / RoHS Status: na

Chapter 5: Functional Descriptions
Stall Behavior and Error Recovery
January 2011 Altera Corporation
Scaler
In the Scaler MegaCore function, the ratio of reads to writes is proportional to the
scaling ratio and occurs on both a per-pixel and a per-line basis. The frequency of lines
where reads and writes occur is proportional to the vertical scaling ratio. For example,
scaling up vertically by a factor of 2 results in the input being stalled every other line
for the length of time it takes to write one line of output; scaling down vertically by a
factor of 2 results in the output being stalled every other line for the length of time it
takes to read one line of input.
In a line that has both input and output active, the ratio of reads and writes is
proportional to the horizontal scaling ratio. For example, scaling from 64×64 to
128×128 causes 128 lines of output, where only 64 of these lines have any reads in
them. For each of these 64 lines, there are two writes to every read.
The internal latency of the Scaler depends on the scaling algorithm and whether any
run time control is enabled. The scaling algorithm impacts stalling as follows:
■
■
■
■
Enabling run-time control of coefficients and/or resolutions affects stalling between
frames:
■
■
■
Error Recovery
On receiving an early endofpacket signal, the Scaler stalls its input but continues
writing data until it has sent an entire frame. If it does not receive an endofpacket
signal at the end of a frame, the Scaler discards data until the end-of-packet is found.
In nearest-neighbor mode, the delay from input to output is just a few clock cycles.
In bilinear mode, a complete line of input is read into a buffer before any output is
produced. At the end of a frame there are no reads as this buffer is drained. Exactly
how many writes are possible during this time depends on the scaling ratio.
In bicubic mode, three lines of input are read into line buffers before any output is
ready. As with linear interpolation, there is a scaling ratio dependent time at the
end of a frame where no reads are needed as the buffers are drained.
In polyphase mode with N
buffers before any output is ready. As with bilinear mode, there is a scaling ratio
dependent time at the end of a frame where no reads are needed as the buffers are
drained.
With no run-time control, there is only a few cycles of delay before the behavior
described in the previous list begins.
Enabling run-time control of resolutions in nearest-neighbor mode adds about 20
clock cycles of delay between frames. In other modes, it adds a maximum of 60
cycles delay.
Enabling run-time control of coefficients adds a constant delay of about 20 cycles
plus the total number of coefficients to be read. For example, 16 taps and 32 phases
in each direction would add a delay of 20 + 2(16 × 32) = 1024 cycles.
v
vertical taps, N
v
– 1 lines of input are read into line
Video and Image Processing Suite User Guide
5–73