Standards Conversion V2.0 Introduction

Standards Conversion V2.0 Introduction
Standards Conversion V2.0
INSTALLATION
Copy the plugins G Advanced Pulldown Converter, G Converter and G Film Converter to the Plugins folder on your hard drive.
For more free and commercial plugins visit www.nattress.com
The Plugins folder is found in: /Library/Application Support/Final Cut Pro System Support/Plugins/ as shown below:
These filters have been tested with FCP3 and FCP4 under OS X. I strongly recommend FCP 4.x for speed and stability while
using the Standards Conversion plugins.
Introduction
G Standards Conversion package contains two complex filters that have been designed to convert between the three
standards of NTSC video (29.97 frames per second), PAL video (25 frames per second) and 24p (24 frames per second
progressive). G Converter deals with the video to video frame rate conversions, and G Film Converter deals with the video to
film frame rate conversions. Both plugins will correctly scale the converted clips if necessary. An new Filter, G Advanced
Pulldown Converter is designed to help users of cameras that shoot with "Advanced Pulldown", such as the Panasonic DVX100
and SDX900, and the Canon XL2.
The Standards Conversion algorithms have bee refined to work both with interlaced and progressive PAL and NTSC. In
Version 2.0 the algorithms have been further refined to work better with Y'CbCr (commonly know as "YUV"), 10bit video and the
chroma sampling of 4:1:1 NTSC DV. Additionally, support has been added to convert 60p footage from a Panasonic Varicam to
24p. In this case, Final Cut Pro does quite a reasonable job of converting from 60p to 24p, but you may find the Film Converter's
solution more visually pleasing.
Both G Converter and G Film Converter work in a very similar manner. This method of working is necessary to bypass the
poor in-built Final Cut Pro / Quicktime frame rate conversion and allow the high quality algorithms to work effectively. Also, if a
change of clip resolution (scaling) is needed, the clip on the timeline should be nested to allow the plugin to work correctly.
Again, due to limitations in FCP, the plugin must be correctly informed of the Source Pixel size of the video that is to be converted.
If you find that there is not a setting for the source media you are using, then please email me at graeme@nattress.com for it is
an easy task to add in the required sizes.
Although conversion will work on a sequence, I have not found this route reliable enough to recommend it's use. Please
use the conversions on movie clips rather than sequences.
General Method
All frame rate conversions begin with making sure you have a project which contains the source movie clip which you wish to
convert and a sequence who's settings match that of which you wish to convert to. For instance, if you wish to convert from PAL
DV to NTSC DV, open a new project, and use the easy setups to create a new sequence that is NTSC DV. Using the easy setups
in Final Cut Pro will ensure that the parameters for the new sequence are specified correctly.
The general method of operation is as follows:
PAL to NTSC conversion
1) edit the PAL clip to an NTSC timeline
2) apply the G Converter clip to the PAL clip in the NTSC timeline (dropping the plugin from the bin onto the nest in the Sequence
is usually easiest)
3) open the clip in the viewer
4) select the filter tab in the viewer
5) set the correct settings for the desired conversion. In this case, we select Source Pixel size to be 720 x 576 (PAL), lower field
order for source (in this case a PAL DV clip) and destination (NTSC DV timeline).
6) if you desire the NTSC output to be de-interlaced, this can be performed in one step by selecting progressive output
7) if you would like to experiment with the conversion algorithm using "Smart De-Interlacing" then this can be selected in the DeInterlace options. The Tolerance control effects the smart de-interlace and it's effects can be seen by selecting "View Smart Mask"
in the De-Interlace Options.
8) the original PAL clip that was edited to the NTSC timeline must now be dropped from the project browser onto the Source Clip
image well in the filter. The plugin will use this this video clip for all the image data for the conversion. This is the important step
that makes this plugin different from any other, and is vital to it's successful operation.
NTSC to PAL conversion
1) edit the NTSC clip to an PAL timeline
2) nest the NTSC clip to allow the plugin to scale the converted clip. Because the pixel dimensions of NTSC video are smaller
than PAL, the clip will appear shrunk down in the timeline canvas viewer. This is normal. The nesting of the clip will allow the
plugin to correctly scale it to PAL pixel dimensions. (select clip and go to the Sequence Menu and select Nest Items - make sure
the pixels dimensions of the nest are PAL sized)
3) apply the G Converter clip to the nest in the PAL timeline
4) open the nest in the viewer (control click on the nest and select "Open in viewer" or select nest then press return)
5) select the filter tab in the viewer
6) set the correct settings for the desired conversion. In this case, we select Source Pixel size to be 720 x 480 (NTSC), lower field
order for source (in this case a NTSC DV clip) and destination (PAL DV timeline).
7) if you desire the PAL output to be de-interlaced, this can be performed in one step by selecting progressive output
8) if you would like to experiment with the conversion algorithm using "Smart De-Interlacing" then this can be selected in the DeInterlace options. The Tolerance control effects the smart de-interlace and it's effects can be seen by selecting "View Smart Mask"
in the De-Interlace Options.
9) the original NTSC clip that was edited to the PAL timeline must now be dropped from the project browser onto the Source Clip
image well in the filter. The plugin will use this this video clip for all the image data for the conversion. This is the important step
that makes this plugin different from any other, and is vital to it's successful operation.
To help follow the special method of use of this plugin, please watch the Tutorial movies on the website at: http://
www.nattress.com that demonstrates this procedure in operation.
NOTE: Standards Conversion works on Sequences as well as clip, although it is not entirely recommended. If you choose
to use sequences, be very careful to check the finished output as sometimes the correct frames from the sequence are
not passed correctly through to the plugin and errors can occur. Be sure to nest the sequence if you are changing it's pixel
dimensions, ie, from NTSC to PAL. If you are using the Film Converter, to just change frame rate, then it is not necessary.
To edit a sequence to the timeline in FCP HD, hold down the Apple key as you do it so that it does not give a mismatched
frame rate error.
G Standards Conversion
Source Clip
-
An "image well" where the original source PAL or NTSC clip must be dropped
Source Pixel Size
-
Selects the pixel dimensions for the source PAL or NTSC clip - (if you need different optional
sizes here, just ask - it only takes me minutes to add them in)
Source Field Order
-
Selects the field order for the source video (must be the same field order that the source clip
was made with)
Destination Field Order
-
Selects the field order for the destination timeline (must be the same field order as the
timeline)
Convert
-
Selects the direction of conversion, PAL -> NTSC or NTSC -> PAL. NEW NTSC Film Source ->
PAL, see below for details.
Source is NTSC DV
-
If you are converting FROM NTSC DV select this option to ensure that NTSC DV 4:1:1 colour
space is dealt with correctly.
Progressive Output
-
this option forces the output to be de-interlaced - doing so may reduce the smoothness of the
conversion, so use with caution.
De-Interlace Options
-
this governs the type of de-interlacing algorithm used in the standards conversion and
progressive output. Normal is the default. Smart takes a little longer to render but may produce
better results. View smart mask allows you to see the smart de-interlace mask as a diagnostic
tool to allow you to set the tolerance correctly.
Tolerance
-
Defines the tolerance of the Smart de-interlace mask.
Motion Blur
-
The conversion algorithm may add some motion blur to the converted video. To control the
amount of motion blur that may be added you can adjust this setting from 0% to 100%.
Reducing the amount of motion blur added may reduce the smoothness of the conversion, so
adjust with care.
Pulldown Offset
-
adjusts the pulldown offset for the NTSC Film Source -> PAL option. See below for details and
warning.
Because Film material is converted to NTSC via 3:2 pulldown, the NTSC Film Source -> PAL option will first attempt to remove
that pulldown before converting to PAL, to ensure a better quality of conversion. For this to work correctly the clip must have
constant cadence - ie, the pattern of the 3:2 pulldown must not change over the length of the clip, and the pulldown offset must be
set correctly for that pattern. At the moment, I know of no easy way to determine the correct setting for the pulldown offset, so
extreme caution must be employed while using the NTSC Film Source -> PAL mode.
G Film Converter
Film Conversion uses the G Film Converter plugin to convert Film from and to video frame rates. This is a more complex filter
than G Converter, but it uses a similar method of operation and algorithms.
NTSC to FILM Conversion
Note: G Film Converter is designed for producing a video to film standards conversion. For removing the 3:2 pulldown on film
telecined to NTSC video, use Apple's Cinema Tools instead.
To convert from NTSC video's 29.97 frame rate to film's 24 frames per second, G Film Converter uses an algorithm similar to
reverse 3:2 pulldown as used in the Film Effects set of plugins. Form more information on this it is advised to download and read
the instructions for Film Effects. G Film Converter allows you to pick from one of the same four methods that Film Effects uses as
outlined below:
1 Field
2 Field
3 Field
3 Field Var
-
Picks the nearest field to the "right" one
Picks the nearest field, and blends it with it's neighbour
Picks the nearest field, and the one before and the one after and blends all three
Picks the nearest filed, and the one after or the one after and one before, in a 3:2 pattern
The more fields used, the smoother the result, but be prepared for an increase in motion blur.
1 Field
-
2 Field
3 Field
3 Field Var -
Can look very good when de-interlace is set to Normal - looks choppy on Smart de-interlace. Do not
use with Motion Blur set to 0% or low percentage values.
Looks very good with both Normal and Smart De-interlace
Has a very smooth look, but also has the most added motion blur
Also has a very smooth look, but also can look like an NTSC kinescope (tele-recording)
for 60p to 24p conversion, the following applies:
1 Field
-
2 Field
3 Field
3 Field Var -
Picks the nearest frame to the "right" one - this is the method that FCP seems to use and should
produce identical results
Picks the nearest frame, and blends it with it's neighbour
Picks the nearest frame, and the one before and the one after and blends all three
Picks the nearest frame, and the one after or the one after and one before, in a 3:2 pattern
FILM to NTSC Conversion
Film to NTSC conversion simply adds standard 3:2 pulldown to the NTSC video to produce the 29.97 frame rate.
PAL to FILM Conversion
PAL to FILM conversion removes one frame every second to reduce the PAL frame rate from 25fps to 24fps. This would produce
a stutter or jump every second, so instead of removing the frame all at once, it is removed a field at a time, so in fact, one field is
removed every half-second. I have called this PAL-1 to Film Conversion. This method has the advantage that the speed of the
resulting film is identical to that of the video.
If you wish to use the "traditional" method of converting Film to PAL or PAL to FILM by speeding up or slowing down by 4% then
please use Apple Cinema Tools and it's conform option to do so.
FILM to PAL Conversion
FILM to PAL Conversion uses the same method that PAL to FILM Conversion uses, but in reverse. For converting FILM to PAL the
Film to PAL+1 Conversion adds one field every half-second to change the Film's 24fps to PAL video's 25fps.
Source Clip
-
An "image well" where the source PAL or NTSC clip must be dropped
Source Pixel Size
-
Selects the pixel dimensions for the source PAL or NTSC clip. For most conversions this
can be left at "Same as Destination". This is because it is not common to change the
frame size when converting to 24p.
Source Field Order
-
Selects the field order for the source video (must be the same field order that the source
clip was made with)
Destination Field Order
-
Selects the field order for the destination timeline (must be the same field order as the
timeline)
Convert
-
Selects the direction and type of conversion, 60p -> 24p, PAL-1 -> 24p, 24p -> PAL+1,
NTSC -> 24p, 24p -> NTSC
NTSC to Film Blending Type
-
Selects from 1 Field, 2 Field, 3 Field and 3 Field Var.
Motion Blur
-
The conversion algorithm may add some motion blur to the converted video. To control
the amount of motion blur that may be added you can adjust this setting from 0% to
100%. Reducing the amount of motion blur added may reduce the smoothness of the
conversion, so adjust with care.
De-Interlace Options
-
this governs the type of de-interlacing algorithm used in the standards conversion,
Progressive PAL and progressive output. Normal is the default. Smart takes a little
longer to render but may produce better results. View smart mask allows you to see the
smart de-interlace mask as a diagnostic tool to allow you to set the tolerance correctly.
Tolerance
-
Defines the tolerance of the Smart de-interlace mask.
Source is NTSC DV
-
If you are converting FROM NTSC DV select this option to ensure that NTSC DV 4:1:1
colour space is dealt with correctly. If you converting TO NTSC DV, do not use this option.
Progressive Output
-
this option forces the output to be de-interlaced - doing so may reduce the smoothness of
the conversion, so use with caution.
Notes on Audio Sync
Standards Conversions normally preserves audio sync. This has been successfully tested on PAL -> NTSC and NTSC -> PAL,
24p -> NTSC, NTSC -> 24p, PAL-1 -> 24p and 24p -> PAL+1.
Final Cut Pro alters the audio speed slightly itself to help in the standards conversion process. In converting PAL to NTSC, it
would seem that if PAL's 25fps was converted to NTSC's 30fps, this would cause issues because NTSC is not exactly 30fps but
29.97fps. However, if the code is set to treat NTSC as exactly 29.97 then audio sync is lost, and in treating NTSC as exactly 30fps
it is preserved. The only explanation for this contradiction is that FCP is slightly altering the speed of the audio behind the scenes.
It is also not known wether when converting NTSC to FILM speed wether it is best to convert to 23.98 or 24 fps, although it is
suspected that by the above logic, FCP itself may handle the slight audio speed conversion necessary.
This means that it is important that the video and audio be converted together, and if you are wanting author a PAL and NTSC
DVD, you cannot use the same audio files for both.
Notes on the Standards Conversion Filter Operation
Once the original clip has been added to the source image well, the nest can be edited (in or out points moved) or moved in time.
The original clip that is added to the timeline must be the clip that is used to drop into the source image well. Any difference in the
in/out points will not give the desired result.
Note on using DSR-11 and DSR-25 Dual format DVCAM Decks
The Sony DSR-11 and DSR-25 DVCAM decks are very useful in a multi-standard environment as they can be switched between
PAL and NTSC operation at the flick of a switch. However, FCP does not like to switch as easily! I find that I have to re-select a
new easy setup and reboot the mac.
G Advanced Pulldown Converter
The G Advanced Pulldown Converter filter is designed for situations where you have shot in 24pAdvanced on a Panasonic
DVX100 or Canon XL2 by mistake. The 24pA footage should really have it's pulldown removed automatically by FCP and edited
on a 23.98fps timeline for best quality. 24pNormal is designed to be edited on a normal NTSC 29.97fps timeline. This filter will
take 24pA footage that has not had it's pulldown removed and convert it to 24pNormal. The filter is designed to be used on a
normal 29.97fps timeline. Filters in FCP cannot access the meta-information which tells FCP where the pulldown frames are in
advanced footage, so there is a small manual step described below to help you find the correct point in the pulldown sequence
for the plugin to work correctly.
1
Place your 24pA footage or clip that does not have it's pulldown removed onto a normal NTSC 29.97fps timeline. Do not
apply the filter yet.
2
Set the canvas in Final Cut Pro to 100% and turn off display as square pixels:
3
Now we can correctly see the interlaced nature of the video and determine wether we're on a split frame or a whole frame. A
Split frame, like the frame shown above will show interlaced tearing - a sort of comb effect. Park the play head on a split frame. It
doesn't matter which. In 24pAdvanced there is one split frame followed by four whole frames. In 24pNormal there are two split
frames followed by three whole frames.
4
Apply the G Advanced Pulldown Converter filter to the clip in the timeline.
5
Advanced the play head one frame.
6
Now adjust the "Pulldown Pattern Shift" control until the current frame you are on is a split frame. This method of operation is
a fairly foolproof method of letting the G Advanced Pulldown Converter filter know exactly where we are in the five frame
pulldown sequence, so that it can accurately convert 24pA to 24pN.
7
Render the clip to see it converted from 24pA to 24pN.
Technical Information
These diagrams illustrate the difference between the 24pNormal (2:3) and 24pAdvanced (2:3:3:2) pulldown patterns.
Also Available at www.nattress.com
Film Effects is the 24p Film Effect for Final Cut Pro. Film Effects does everything
you need to make your video look like film - whether NTSC or PAL
©2005 Nattress Productions Inc.
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