DE285 HD Caption Decoder/VANC Monitor
Caption Error
Description
CDP checksum error
The CDP footer contains a checksum for the
entire CDP; if you see this, it didn’t match
what the decoder expected.
CDP length mismatch
The CDP header contains an 8-bit length
count; if you see this, the length didn’t match
the number of bytes actually recovered.
CDP frame rate mis-
match
The frame rate indicated by the CDP header
doesn’t match the video. For example, you’ll
see this if you capture VANC captions in 720p
and play them back in 1080i.
Invalid
CDP
frame
rate
The CDP frame rate was something nonsensi-
cal; for example, zero.
Wrong number of CC
constructs
The CDP count of caption data pairs didn’t
match what was actually recovered.
No line 21 captions
No 608 data was found.
Bad line 21 alterna-
tion
In 720p, the 608 data are supposed to alter-
nate between field 1 and field 2; this means
that two consecutive frames of one or the
other went by.
No line 21 field X
In 1080i, each frame is supposed to have field
1 and field 2 data for 608.
Line 21 not first in
packet
The 608 bytes are supposed to come first in
the caption data section of the CDP, before
any 708 data.
Bad DTV triplet
In the CDP caption data section, 708 data are
split into pairs and marked with 0xFF(start
of a caption channel packet) or 0xFE(next
part of a CCP). 608 data are marked with
0xFC(field 1) or 0xFD(field 2).
The rest of
the caption data section should be filled with
pairs marked 0xF8, 0xF9, 0xFA or 0xFB. If a
DTV triplet doesn’t begin with any of those
markers, this message will appear; it might
mean the DTV packets are misaligned.
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