[mythtv-users] Problems with Bob under XvMC

Doug Larrick dougl at charter.net
Mon Sep 13 09:36:34 EDT 2004

Rob Hillis wrote:

 > On a slightly different note, can anyone tell me exactly what the
 > advantages of Bob de-interlacing are?  Yes, the picture here seems to
 > be fairly clear and clear, though it has an incredibly annoying
 > vertical jitter on anything with sharp edges (i.e. the OSD and
 > titles/credits)

Bob deinterlacing shows the two fields of an interlaced video
sequentially.  This is what a normal interlaced display does, so it
should look the most similar to actually running your HDTV/monitor as

 > Which de-interlacing methods yeild the best results for people?
 > Currently I'm using Kernel which does the job nicely on my 19" CRT
 > monitor.   Bob did appear to be a bit sharper, but the jitter drove me
 > nuts... :)

When you say you see jitter with bob, does it look like maybe the fields
are displayed in the wrong order?  There's code in libavcodec that's
supposed to determine the field order, but maybe it's getting it wrong
for your videos.

Linearblend averages sequential fields.  Removes artifacts but can be
blurry or ghosty.
Kernel looks at several fields to try to minimize blurring and ghosting.
Bob is described above.
Onefield is like bob, but throws out every other field.

As an aside, though... if you're using XvMC, you're not using these
filters at all.  The only deinterlacing that can be done with XvMC is
bob, and it's done with entirely different code.


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