Could someone explain why a video DVD played on my computer looks fine but if I make an Mpeg2 file and play it on my computer it has the comb/Interlace lines? I understand that it will play back fine on a TV. But why is it that way on the computer when the store bought DVD doesn’t do this. If I deinterlace would that change things? I capture it in Abode Premiere and it looks fine, only when I output to Mpeg2 does it do this. Is there a setting I could change to make it look good on a computer and tv?
Thanks for any insight.
Jim
starbuck@gate.net
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Ok, But why would the store bought DVD shown on the computer not have interlace lines? Could I output in progressive mode?
Jim -
I'll give you a free bump by re-asking the question, as
I have had the same experienece!
Why does a store bought DVD (destined for a TV interlace display)
played on a computer (progressive display) show no interlace
artifacts and a local captured MPEG2 (also destined for TV
interlace display) does show the interlace artifacts on the
computer???
We understand displaying interlace on prgressive will cause
the problem, but what is it about the stamped DVD's that
eliminate this issue??
-n6nfg -
Because, most stamped DVD's contain material that was created from FILM sources, which are inherently PROGRESSIVE. If the DVD contained material that was shot on standard video cameras, such as some concert footage or CNN newsreels, these would be sources that were INTERLACED (holds true for PAL or NTSC) and thus you would notice the usual interlace lines on your computer monitor with these discs, too. Don't be confused by TV series (Sopranos, etc), cuz these actually are largely shot on film.
Home video cameras are interlaced-ANALOG or DIGITAL (not counting those few that are switchable).
Clear as mud, right?
Scott -
If I deinterlace would that change things? I capture it in Abode Premiere and it looks fine, only when I output to Mpeg2 does it do this.
***
If you have something that was shot on home video, it is INTERLACED, e.g. DV footage.
If you're going to display it on TV (99% of all of them are interlaced) and Computer Monitor (99% of them are progressive), or if it's just output to TV, it doesn't make sense to deinterlace. You'll be losing vertical resolution and temporal resolution and adding judder, just for a small increase in coding/storage efficiency. (This also assumes the storage/replay mechanism supports interlaced material--DV/MPEG2/DVD/SVCD/CVD).
If-you know your interlaced material will ONLY be shown on Progressive display devices, -OR- if your storage medium doesn't support interlacing (MPEG1/VCD), then it makes sense to deinterlace. Then, there will be less-maybe even NO-comb/line artifacts.
Of course, the waters could be muddied by incorrect or combined methods at the interim stages.
*NOTE*:
Adobe Premiere will often show an internally de-interlaced signal on computer monitors (without explicitly telling you-except in the manual)-don't be sidetracked by this: the material is still at that point INTERLACED.
Try this:
Create a bunch of stills, start a Premiere project-set as NON-INTERLACED/PROGRESSIVE @24fps. Make transitions between the stills. Export as a Huffy AVI movie. Use TMPGEnc with SVCD 24fps/pulldown template, burn to CDRW and see that it will play smoothly-on Computer or TV, just like storebought FILM DVD's. 8)
Scott
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