#2452: decoding yuv420p to rgb shifts luminance down
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Reporter: burek | Owner:
Type: defect | Status: new
Priority: normal | Component:
Version: unspecified | undetermined
Keywords: | Resolution:
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 0
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Comment (by glopes):
Yes, I didn't check the actual mpeg4 frames (sorry if I wasn't clear).
What I did check was the raw grayscale pixel intensities of the data
coming in through the camera ''before it was encoded'' and then compared
it to the pixel intensities of the reconstructed frames ''after
decoding''.
So if the previous gray encoder/decoder pair was buggy it's interesting
why they allowed me to reconstruct the pixel intensities perfectly in the
first place.
As to the last question, I just checked and I can find values ranging from
8-255 without much effort. Not sure if there's absolute zeros in there
because of lighting conditions, but it definitely looks like I'm full
range (which doesn't happen with this current version, where pixels
everywhere from [8-14] get squashed to 0).
Don't have access to the setup right now, will try to make do. If I manage
to reproduce anything meaningful about encoder differences, I'll let you
know.
I'm still learning about pixel format specifications, but I guess what I
mean to say is that somehow the bytes that were encoded in the file
contain information about the correct pixel intensities. I just want to
make sure I can read them back...
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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2452#comment:10>
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