[mythtv] [filtering] Cross lines cause unalignment [DeInterlace/Linearblend]

[Kenneth Aafløy]

Hi List!

These facts will not occur on a properly aligned output device souch as
the PVR-350 output.

This is a fact that has annoyed me since I started thinking about
supporting the MythTV project. What is the (probable) cause is that two
FRAMES, A and B, is getting deinterlaced as follows:

The two FRAMES contains as we know, two FIELDS:

When FRAME A get deinterlaced into a FRAME each % 2 line of the
deinterlaced picture moves a slight bit, to adjust to the previous line,
so that interlacing artifacts won't show up on a non-deinterlaced
display device.

When this fact for FRAME a happends to FRAME b, the picture will become
extreamily jagged, because lines between the frames is not considered.

This is a fact that a filter has to be developed for, but I don't really
have the knowledge to implement it (although keen to learn, if anyone
cares).

With the postprocess filter, artifacts has been minimised, but this
artifact still remindes, since the postprocess filter is a per frame
filter.

Kenneth