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Old 25th June 2013, 22:14   #1  |  Link
jq963152
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60i to 30p (or 50i to 25p) without artifacts?

Hello,

is it possible to convert 60i* to 30p (or 50i* to 25p) without artifacts?

*truly interlaced, not progressive segmented frames
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Old 25th June 2013, 22:39   #2  |  Link
manono
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Originally Posted by jq963152 View Post
is it possible to convert 60i* to 30p (or 50i* to 25p) without artifacts?
That's kind of a loaded question. Have you tried something like:

QTGMC( Preset="Slow" )
SelectEven()
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Old 25th June 2013, 23:11   #3  |  Link
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If you don't mind sacrificing resolution, you can do the selecteven() and then resize to 1/2 in the horizontal direction. Of course that degrades the video in a different way. Which brings us back to the key question here: what do you mean by "without artifacts?"
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Old 25th June 2013, 23:26   #4  |  Link
jq963152
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what do you mean by "without artifacts?"
Well, converting 60i to 30p (or 50i to 25p) usually results in jaggies, doesn't it?

When converting 60i to 60p (or 50i to 50p) it usually is much better, isn't it?

So is there any way to get smooth results when converting 60i to 30p (or 50i to 25p)?

Or is 60i to 60p (or 50i to 50p) the only way?

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Originally Posted by johnmeyer View Post
If you don't mind sacrificing resolution
In this case i would prefer spatial resolution over temporal resolution.

Of course i would rather like to have both, spatial resolution and temporal resolution, but i guess that's only possible when converting 60i to 60p and not possible when converting 60i to 30p?

So in that case i guess i would have to choose between spatial resolution or temporal resolution?
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Old 26th June 2013, 00:15   #5  |  Link
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Manono gave you an excellent answer. Try it and report what you get.
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Old 26th June 2013, 04:19   #6  |  Link
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bobbing is better than deinterlacing for truly interlaced videos, 60i to 60p is perfect, why do you want 30p exactly?
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Old 26th June 2013, 15:46   #7  |  Link
jq963152
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60i to 60p is perfect, why do you want 30p exactly?
I don't want it.

But 1920x1080p60 support basically is non-existent in consumer hardware .
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Old 26th June 2013, 20:46   #8  |  Link
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Originally Posted by feisty2 View Post
bobbing is better than deinterlacing for truly interlaced videos, 60i to 60p is perfect, why do you want 30p exactly?
Perfect?

Show me perfect 60i to 60p conversion (not using QTGMC)?
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Old 26th June 2013, 21:38   #9  |  Link
davidhorman
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Well, converting 60i to 30p (or 50i to 25p) usually results in jaggies, doesn't it?

When converting 60i to 60p (or 50i to 50p) it usually is much better, isn't it?

So is there any way to get smooth results when converting 60i to 30p (or 50i to 25p)?
I'm not sure you're phrasing your question very well. The only thing I can think you mean by "jaggies" is the "judder" of having only 30 frames per second, in which case, no you can't get smooth results because - obviously - you've only got 30 frames per second to work with.

Unless you mean the jagged lines you get from something like a plain bob - in this case these are less obvious if can output to 60p because they're on alternating lines in neighbouring frames (and also the frames are refreshed more often). In fact this is almost what you see when you're watching a CRT TV. They're still there, though, and to reiterate manono's advice, QTGMC does a great job of reducing the problem whether you're outputting to 30p or 60p.

For a better answer, can you provide a sample of the source?
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Old 27th June 2013, 13:20   #10  |  Link
feisty2
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Originally Posted by kolak View Post
Perfect?

Show me perfect 60i to 60p conversion (not using QTGMC)?
"perfect",I mean bobbing is "better" than deinterlacing
EDIT:what I mean about "bobbing" and "deinterlacing" are both done in QTGMC

Last edited by feisty2; 28th June 2013 at 13:20.
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Old 27th June 2013, 15:27   #11  |  Link
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Pure Bobbing is terrible if you ask me.

In any case, if you have a properly preserved interlaced stream, a good deinterlacer can deinterlace that to 60p with hopefully very few artifacts, if any at all.
From the 60p, you can just decimate to 30p.

Otherwise, just upscaling every other field of course also works, perfectly artifact free - but with reduced vertical resolution.
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Old 27th June 2013, 21:38   #12  |  Link
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Pure Bobbing is terrible if you ask me.
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Originally Posted by nevcairiel View Post
Otherwise, just upscaling every other field of course also works, perfectly artifact free - but with reduced vertical resolution.
"Pure Bobbing" (like Bob()) does exactly that, resize the fields (of which you can throw away every other one if needed).
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Old 28th June 2013, 08:37   #13  |  Link
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"Pure Bobbing" (like Bob()) does exactly that, resize the fields (of which you can throw away every other one if needed).
Well if you throw away every other field, its not bobbing anymore. The typical effect of the image slightly jumping up and down goes away, which is what i mostly hate about bobbing.
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Old 28th June 2013, 12:08   #14  |  Link
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Maybe I wasn't clear
If you do this:

Bob().SelectOdd()

You get exactly this:
Quote:
Originally Posted by nevcairiel View Post
The typical effect of the image slightly jumping up and down goes away

Im just trying to tell you that there's no difference whether you Bob() first and then drop every other frame (which was a field originally) or if you just grab a field and resize it.

Wait, there is a difference. Simply resizing a field to full height like this

SeparateFields().SelectOdd()
Resize(Width, Height*2)

will not correct the field's vertical offset. Bob() does that.

See the explaination of the AviSynth doc about Bob().
Quote:
If you just did a resize vertically by a factor of 2 on each frame* after doing a SeparateFields(), then it wouldn't work right because the physical position of a field moves.
*actually field
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Old 28th June 2013, 15:27   #15  |  Link
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Originally Posted by jq963152 View Post
But 1920x1080p60 support basically is non-existent in consumer hardware .
There are HDTV camcorders that do this, for a long time now.
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Old 28th June 2013, 16:00   #16  |  Link
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There are HDTV camcorders that do this, for a long time now.
That doesn't change the fact that most consumer hardware players can not play back 1920x1080p60 video though...
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Old 28th June 2013, 19:14   #17  |  Link
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Well, you could use a PC...
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Old 28th June 2013, 20:40   #18  |  Link
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Originally Posted by jq963152 View Post
That doesn't change the fact that most consumer hardware players can not play back 1920x1080p60 video though...
My Xtreamer Prodigy, SideWinder 3, XtreamerTV and Oppo BDP-103 can.

EDIT: Looks like my LG 32LS570T TV can too
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Last edited by SeeMoreDigital; 28th June 2013 at 21:19.
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Old 28th June 2013, 21:11   #19  |  Link
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Originally Posted by jq963152 View Post
That doesn't change the fact that most consumer hardware players can not play back 1920x1080p60 video though...
So, we moved away from "basically none" to "most don't".
60p is integrated since at least 5 years in both Realtek and Sigma Design chips, so it's a matter of firmware.
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Old 28th June 2013, 21:26   #20  |  Link
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All modern high-end settop box silicon supports 1080P60, and higher-end silicon supports multiple decoding of 1080P60 and transcoding on the fly.
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