Avisynth: LetterBox parameters?
 

how LetterBox works and in what case is used?
have i use in the last script if the source is dvd?
advantages?
is only for captures?
yeah,many questions.

see my values for bicubic and addborders in the last script:
i don't use overscan = 2 cos give black bars on the left in my tv,
then i choose overscan = 1 :!:
.....
undot()
Limiter()
asharp(2,4)
FieldDeinterlace()
BicubicResize(464,464,0,0.6,0,0,712,480)
STMedianFilter(8,32,0,0)
MergeChroma(blur(MaxTreshold))
MergeChroma(blur(0.2))
ScriptClip("nf=YDifferenceToNext()"+chr(13)+"nf>2. 5?asharp(-(fmin((nf/30),1)),0):\
TemporalSoften(2,7,7,3,2)")
ScriptClip("nf>scd_trigger?asharp(-2,0):asharp(0,0)")
AddBorders(8,8,8,8)
Limiter()
function fmin(float f1,float f2){return(f1<f2)?f1:f2}

:?:
and what filter is better to deinterlace? (i'm using decomb)
i read that with more than 480x480 we don't need to use deinterlace.
this information is right?
:?

thanks for all informations.
:)

Hi jorel,

I'm not sure but I think the letterbox command prevents the whole image to be filtered. It's no point filtering the black borders of a widescreen movie, right? :wink:
Regarding the question about Deinterlace I think (once again not sure!) you need to Deinterlace no matter what resolution you use. Unless you're making a MPEG-2 (SVCD) movie. MPEG-1 does not support interlaced material and you will end up with an interlaced picture - not very fun to watch! And I personally use Decomb everytime I encode an interlaced movie...

-audioslave

thanks my friend
:wink:

"It's no point filtering the black borders of a widescreen movie, right?"
i'm loose here, please explain me again!
:oops: (my poor english)

Read the Avisynth docs, LetterBox is explained best there.

You must deinterlace if your source is interlaced. With a progressive source, deinterlacing is not needed.

However, there are different scenarios in which different methods are used. I think that most NTSC DVDs just need Force-FILM to be enabled in DVD2AVI, leaving progressive frames intact and in that case, deinterlacing is not needed.

With pure interlaced source, FieldDeinterlace() is enough (please correct me if I'm wrong :wink: ). Otherwise, Telecide() could be the solution - as you can see, it's very confusing..there are some guides on the net that explain interlacing very well, the best explanation that I know of is at www.100fps.com (down at the moment :? )

@jorel

What I meant was:
On a widescreen movie you have two black fields on the upper and lower part of the picture. Looks almost as if you have the movie on a black background with the movie in the middle. Do you follow?

-audioslave

thanks Boulder and audioslave
:wink:

"Do you follow?"

yes but don't know how to use the parameters and
avisynth org and docs are confused for me! :?

@jorel

The Letterbox parameter consist of four numbers. Like this for example:

Letterbox(56, 56, 4, 4)

Where the first number is the top of the picture, the second is the bottom, the third is the left side and the fourth is the right side.
The example I wrote is the parameters I used for "Red Dragon"...
I don't know if there's an easy way of getting the right numbers. I load my script (*.avs) into VirtualDub and change them until I'm satisfied. I always use "Letterbox()" with the lastest adaptive script because the blurring between scenes shows on the letterbox edges as well. I change the first and second parameter so I get a sharp edge between the movie and the letterbox fileds :wink: !

-audioslave

EDIT: You have to use even numbers. You can't use 1, 3, 5 etc.

:D
now seems easy:
"I load my script (*.avs) into VirtualDub
and change them until I'm satisfied."
"You have to use even numbers. You can't use 1, 3, 5 etc."
:o

i will do like you to try.
:wink:

thanks for help and patience my friend!
:)

@jorel

No problemo, my friend! Glad to help... :wink:

-audioslave

Hi Jorel, sorry if you may know some of this but for your information thought I would brain dump. Hope some of it is relevant. AddBorders() adds pixels around the boarder of your active film to achieve the final resolution. Letterbox() clips (not crops) or blacks out the pixels that are there but does not change the resolution.

Moviestacker will give you the parameters you need. Suggest you use Gripfit. Here's how:

Using "overscan" in "resize" mode will bring the picture in at the sides but will shrink in vertical as well to retain Aspect ratio.

Widescreen movies you need all the height you can get, use "overlap" instead. Overlap just clips (using Letterbox()) at the sides. You 'lose' some original picture in the width but you don't see it on the DVD anyway and you gain some file size with your encode.

With Full Screen "Resize" is fine however and would be preferred to get all the original film inside the TV/Monitor area.

To work out how many units of overscan, this depends on your TV. As a rule, for resolution KVCDx3 and above "2" should be OK. For res below this use "1". Test it out. Hope this helps and more importantly I hope it is right.

ozjeff99

thanks too ozjeff99!

was very clear and help a lot.
:)

:D
thanks again Boulder.

the link is working and is cool!
http://www.100fps.com/

Just one more tip: I use a Vdub filter called Border Control (http://www.geocities.com/siwalters_uk/fnews.html) to find my border settings. This filter is dynamic in Vdub so it is pretty easy to find the correct values to use in Avisynth.

great Mr :!:

did you believe that i knew the link,
download the file a few days ago but never test it? 8O
and the best: have avisynth version too!

thanks a lot MrTibs!
:D