video_encoder_dv.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<title>VENC testing</title>
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<h1>Video Encoder Testing</h1>
The purpose of this document is to describe briefly the video encoder tests
that have been created to validate the operation of the Ricoh encoder core
and its integration into the BB SoC. We assume the internals of the encoder
are correct, so the purpose is mostly to check that it works in the BB SoC.<br>
<br>
Inputs to the Encoder are:<br>
<br>
PSRGB[6:0]: Sync and RGB, from VI<br>
PTCLK: Video Clock input<br>
PTSYNCB: Sync input, from VI<br>
PTESTIO: Test input pin, held low in all our tests, except to cause internal
reset to a know state<br>
PNTPL: NTSC/PAL, low means PAL, high is NTSC<br>
PMPAL: MPAL mode, high means MPAL, regardless of PNTPL signal<br>
PTRAPB: Low, trap filter on, High trap filter is controlled by bit 4 of sync
data (on PSRGB).<br>
<br>
Outputs are:<br>
<br>
COUT[7:0]: Chroma output, connected to DAC<br>
VOUT[7:0]: Composite output, connected to DAC<br>
YOUT[7:0]: Luma output, connected to DAC<br>
CLK24DAC: Clock output (1/2 input clock) connected to DAC<br>
<br>
<br>
To test the encoder 3 tests are run which have NTSC, PAL and MPAL enabled.
Each are driven by their correct clocks from the video PLL. See rf/sw/bbplayer/iosim/tests/[venc_ntsc.tst,
venc_pal.tst, venc_mpal.tst].<br>
<br>
To test basic connectivity of the input and the outputs to the DAC we use
two different input signals:<br>
<ol>
<li>A line consisting of a luma ramp (no color), from 255 to 0, repeating
over a complete 640 pixel line</li>
<li>A line of color bars set at 75% saturation (Grey, Yellow, Cyan, Green,
Magenta, Red Blue, Back)</li>
</ol>
The output was verified visually by dumping the digital outputs internal
to the Video DAC. Any misconnect of the input or output (PSRGB, PTSYNCB,
PTCLK, COUT, VOUT, YOUT, CLK24DAC) would clearly show up as non-linear ramp,
or incorrect chroma signal. The color bar results where matched against the
results shown in Video Demystified.<br>
<br>
The PTESTIO pin is implicitly tested since it is necessary to pull this line
high for 4 clocks, low for 30 clocks and high for another 4 clocks to get
the encoder to reset to a known state. If this is not done the outputs are
all X.<br>
<br>
To test the control lines (PNTPL, PMPAL) the ratio of the color burst frequency
to the video clock was tested. The output video sampling clock is the input
clock/2, and the ratio of the color burst to input clock is 13.6 for NTSC
and MPAL and 11.2 for PAL. The measured number of samples for the color bursts
where as follow:<br>
<ol>
<li>NTSC: 61/9 = 6.78</li>
<li>PAL: 45/8 = 5.625</li>
<li>MPAL: 61/9 = 6.78</li>
</ol>
This is close to the expected results.<br>
<br>
XXX Still haven't figured out how to check VTRAP wiring.<br>
<br>
<br>
<br>
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