Hi!
I was playing around with some code to generate EDIDs, and I think I
found a bug in how edid-decode parses the landscape and portrait ratio
in the base block, bytes 0x15 and 0x16.
The spec (section 3.6.2) provides a formula to get back the aspect ratio
from the stored value which is:
in landscape
aspect ratio = (stored value + 99) / 100
With the value in the byte 0x15
and in portrait
aspect ratio = 100 / (stored value + 99)
with the value in the byte 0x16
However, parse-base-block.cpp has:
if (x[0x15])
printf(" Aspect ratio: %f (landscape)\n", 100.0 / (x[0x16] + 99));
else
printf(" Aspect ratio: %f (portrait)\n", 100.0 / (x[0x15] + 99));
Which applies the same formula to both ratio types, and seems to invert
the bytes supposed to be used?
The spec provides some example later on, for example with 4/3 (so
1.333333...) where the stored value is supposed to be 34/0x22, while
edid-decode parses that as 1.010101
Maxime
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