View source for YV12InterlacedReduceBy2

{{FilterCat4|External_filters|Plugins|Adjustment_filters|Resizers}}
{{Filter3
| {{Author/Tom Barry}}
| v0.1.1.0
| [http://web.archive.org/web/20111205012101/http://neuron2.net/trbarry/YV12InterlacedReduceBy2.zip YV12InterlacedReduceBy2.zip]
| Resize 
|5=[http://www.gnu.org/licenses/gpl-2.0.txt GPLv2]
|6=[http://forum.doom9.org/showthread.php?t=47852 Doom9 Thread]}}
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== Description ==
InterlacedReduceBy2 is a fast Reduce By 2 plugin, it includes 3 resizing filters.

*{{Template:FuncDef3|InterlacedReduceBy2}} works by taking only the even (starting with 0) pixels from the top field. So it will reduce both the width and height by a factor of 2. It blends the chroma slightly to avoid YV12 chroma delay.

*{{Template:FuncDef3|InterlacedReduceBy2At60}} is the same as <tt>YV12InterlacedReduceBy2</tt> except it outputs 60 (or PAL 50) FPS, using both the top and bottom interlaced fields as source.  Use this one if you get jerky motion on 30 FPS encodes.

*{{Template:FuncDef3|YV12InterlacedSelectTopFields}} selects the top fields only and adjust for chroma delay but leaves the width unchanged.
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== Requirements ==
* AviSynth 2.5.8 or later
* Supported color formats: [[YV12]]

* [[SSE]], [[MMX]] capable CPU
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== [[Script variables|Syntax and Parameters]] ==
:{{Template:FuncDef|YV12InterlacedReduceBy2 (clip)}}
:{{Template:FuncDef|YV12InterlacedReduceBy2At60 (clip, int)}}
:{{Template:FuncDef|YV12InterlacedSelectTopFields (clip)}}
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::{{Par2| |clip| }}
:::Input clip.
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::{{Par2| |int| }}
:::<tt>'''topfirst'''</tt>: 0 for bottom field first (BFF), 1 for top field first (TFF).
:::When in doubt just try it both ways. One will be obviously wrong if you step through it one field at a time in VirtulDub. 
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::*'''Note:''' all parameters are unnamed and do not have a default so they must be specified.
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==Examples==
Assume you have a 1920x1080 interlaced clip.
 [[AviSource]]("blah.avi")
 InterlacedReduceBy2()
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== Changelog ==
 Version       Date            Changes<br>
 v0.1.1.0      2005/03/20      - Added YV12InterlacedReduceBy2At60(1) support
 v0.1.0.0      2003/03/01      - Initial release
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== Archived Downloads ==
{| class="wikitable" border="1"; width="600px"
|-
!!width="100px"| Version
!!width="150px"| Download
!!width="150px"| Mirror
|-
!v0.1.1.0
|[http://web.archive.org/web/20111205012101/http://neuron2.net/trbarry/YV12InterlacedReduceBy2.zip YV12InterlacedReduceBy2.zip]
|[http://www.avisynth.nl/users/warpenterprises/files/yv12interlacedreduceby2_5F25_dll_20050320.zip yv12interlacedreduceby2_25_dll_20050320.zip]
|}
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== External Links ==
*[http://avisynth.org.ru/docs/english/externalfilters/yv12interlacedreduceby2.htm avisynth.org.ru] - YV12InterlacedReduceBy2 documentation, [http://avisynth.org.ru/docs/russian/externalfilters/yv12interlacedreduceby2.htm Russian].
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