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Post #508397

Author
Moth3r
Parent topic
Laserdisc players - screenshot comparison
Link to post in topic
https://originaltrilogy.com/post/id/508397/action/topic#508397
Date created
22-Jun-2011, 8:32 AM

Moth3r said:

[...]

With this [LG] recorder [...]

The main disadvantage is the weird interlaced chroma problem at the top and bottom of the colour bars. Might be due to a sub-sampling error in the MPEG-2 encoding/decoding.

Looking at this again, the issue is obvious. DVD recorders encode to MPEG-2, which uses 4:2:0 YUV (YV12) colour subsampling. The recorder has no way of knowing whether the material you are recording is interlaced or progressive; this particular model assumes it is interlaced and flags each frame as such.

When upconverting from YV12 to RGB24 for a screenshot, DGIndex looks at this flag to decide how it should upsample the chroma, the error seen on those screenshots above are due to incorrect assumptions used for the upconversion. If you force progressive type upsampling, the problem is fixed.