In article <vnv4du0p2ditk649ustosq2er9jueubqbm@4ax.com> , Scott Moore 
<sdm### [at] zoomcouk>  wrote:

> On second thoughts, I won't post some images - I see where you're
> coming from. <thinking out loud> If you want a 100 frame interlaced
> animation you need to produce 200 images using POV with field
> rendering turned on and then use another tool to interlace them into
> the final 100 frames. Hmm, 3ds max is doing this final step for you.

You are not the first person to be confused about this.  I suppose I small
note about this littel but important difference should be added to the
documentation...


    Thorsten


____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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Reading through some of the posts here I can see that there is quite a bit
of confusion about how POV implements its field rendering. If you have a
look back at my earlier posting it describes how the lines and fields are
output by POV. Yes, like 3DS or other programs it needs to parse the scene
twice for each frame because in an animation the position of objects will
have changed between the two fields.

The problem is that in POV the two fields are output to two separate files
which is quite bizzare. And each field/file has alternate lines which are
redundant. Thorsten says he believes that "Premiere" and other editing
programs must have a feature that can interleave the POV file/fields and
that he therefore can't see the problem - I'm not so sure that such features
exist which can interleave POV fields correctly. As I expalined earlier the
"interleave frames" feature on Premiere doesn't do what is required to merge
POV field-pair files into single properly interleaved frames (actually it
goes part of the way but you would then need to delete alternate frames in
Premiere because the alternate frames are comprised of the redundant lines
from the POV output targa files). I may be wrong but I can't see that an
editing program would need a feature which performed the kind of interlacing
which the POV files require.

What POV ought to do when field rendering is switched on, is to create a new
numbered targa file only for fields 1, 3, 5, etc and to write the "odd"
field lines into the file; and then for fields 2, 4, 6 etc it should RE-OPEN
the previous file and write the "even" lines between the previously written
odd lines. Then you would end up with half the number of files and each file
would contain a complete and properly interleaved frame.

I can't see why POV should not do field-rendering this way, it would remove
a lot of the hassle of trying to merge the exiting output files. I know that
POV needs to calculate the redundant lines in memory if anti-aliasing is
switched on, but there's nothing to stop it only outputting the alternate
"used" lines to file.

I have just about finished a program which will do this interlacing, but it
really shouldn't be necessary.

Incidentally, I'm not to keen on the terms "odd" and "even" when refering to
fields as they are ambiguous, depending on whether you start counting from
line 1 or 0. When someone mentions the "odd" field you really can't be sure
which they mean. Unfortunately POV uses this terminology and appears to
start at line 0. I wish they would use "upper" or "lower" field instead as
this is unambiguous.

Colin


"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3cd2db83@news.povray.org...
> In article <vnv4du0p2ditk649ustosq2er9jueubqbm@4ax.com> , Scott Moore
> <sdm### [at] zoomcouk>  wrote:
>
> > On second thoughts, I won't post some images - I see where you're
> > coming from. <thinking out loud> If you want a 100 frame interlaced
> > animation you need to produce 200 images using POV with field
> > rendering turned on and then use another tool to interlace them into
> > the final 100 frames. Hmm, 3ds max is doing this final step for you.
>
> You are not the first person to be confused about this.  I suppose I small
> note about this littel but important difference should be added to the
> documentation...
>
>
>     Thorsten
>
>
> ____________________________________________________
> Thorsten Froehlich, Duisburg, Germany
> e-mail: tho### [at] trfde
>
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

In article <3cd30b70@news.povray.org> , "PovRAY" <cbd### [at] my-dejacom> wrote:

> Thorsten says he believes that "Premiere" and other editing
> programs must have a feature that can interleave the POV file/fields and
> that he therefore can't see the problem - I'm not so sure that such features
> exist which can interleave POV fields correctly.

As for Adobe Premiere I know it has it.  And I believe other programs on other
platforms have it as well.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

> What POV ought to do when field rendering ....
> RE-OPEN the previous file and write the "even" lines
> between the previously written odd lines. Then you
> would end up with half the number of files and each file
> would contain a complete and properly interleaved frame.

I agree, that this would be an improvement.

> I'm not to keen on the terms "odd" and "even" when refering
> to fields as ...... I wish they would use "upper" or "lower"
> field instead as this is unambiguous.

I agree with this, too.

Regards,
Hugo

Post a reply to this message

In article <3cd3ce88$1@news.povray.org> , "Hugo" <hua### [at] post3teledk> wrote:

>> I'm not to keen on the terms "odd" and "even" when refering
>> to fields as ...... I wish they would use "upper" or "lower"
>> field instead as this is unambiguous.
>
> I agree with this, too.

The terms "odd" and "even" are the correct technical terms which are used in
all technical literature and all (professional) software.  In fact I have
never seen "upper" or "lower" been used before anywhere, and they don't really
make sense either when dealing with something that is counted...

    Thorsten


A few references:

* Bt848/848A/849A Single-Chip Video Capture for PCI Data Sheet
  Brooktree Corporation

* AD724 RGB to NTSC/PAL Encoder Data Sheet
  Analog Devices, Inc.

* LM1881 Video Sync Separator Data Sheet
  National Semiconductor Corporation

* QuickTime 5 API Reference
  Apple Computer, Inc.

* Media Composer 1000 User Manual
  Avid Technology, Inc.



____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3cd3a44c@news.povray.org...
> In article <3cd30b70@news.povray.org> , "PovRAY" <cbd### [at] my-dejacom>
wrote:
>
> > Thorsten says he believes that "Premiere" and other editing
> > programs must have a feature that can interleave the POV file/fields and
> > that he therefore can't see the problem - I'm not so sure that such
features
> > exist which can interleave POV fields correctly.
>
> As for Adobe Premiere I know it has it.  And I believe other programs on
other
> platforms have it as well.

I'd be grateful if you can tell me where the feature is in Premiere, because
I can't find anything which does this.

The closest is "interlace fields" but as I said earlier this interlaces both
fields of all frames, so you would then have to manually delete alternate
alternate frames and close up all of the gaps which is very laborious.

Post a reply to this message

"Thorsten Froehlich" <tho### [at] trfde> wrote in message
> The terms "odd" and "even" are the correct technical terms which are used
in
> all technical literature and all (professional) software.  In fact I have
> never seen "upper" or "lower" been used before anywhere, and they don't
really
> make sense either when dealing with something that is counted...

I am very surprised that you have never seen "upper" or lower" used
anywhere.

Premiere has a project setting for "upper or lower field first" which it is
very important to get right.. Also a quick search on the web will throw up
numerous technical pages which refer to "upper" and lower"  fields, such as
this on google which includes technical pages from the Adobe site:

http://www.google.com/search?hl=en&q=upper+lower+field+video

There's also a good explanation of why "odd" and "even" are ambiguous on the
oft-linked-to Lurkers Guide to Video. There's a small section entitled
"Thoroughly Ambiguous: Avoid The Terms Even and Odd" half way down this
page:

http://www.lurkertech.com/lg/dominance.html

I accept that many specs assume that the reader appreciates that line
numbering starts from 1, but this is not universal.

> "upper" or "lower" ... don't really make sense either when dealing with
something
> that is counted...

But that is the problem. It depends what number you start counting the lines
from - 0 or 1. If you start from 0 then the top line is part of the even
field, but if you start from 1 it is part of the odd field. Some specs may
say that line numbers (or field numbers) start from 1, but there are a lot
of sources including Pov-Ray which start numbering from 0. Consequently if a
program only tells you that its output has the odd frame temporally before
the even field you don't know for certain whether the field containing the
top line is the earlier or later - and you need to know this. Once you have
imported this clip into Premiere you don't have to count lines, but you must
know whether the field which includes the top line (the upper field) is
temporally earlier than the other (lower) field otherwise your finished
project may playback on interlaced devices with jitter.

Colin







Never? The project settings of Premiere require you to set "upper" or
"lower" field first.



>
>     Thorsten
>
>
> A few references:
>
> * Bt848/848A/849A Single-Chip Video Capture for PCI Data Sheet
>   Brooktree Corporation
>
> * AD724 RGB to NTSC/PAL Encoder Data Sheet
>   Analog Devices, Inc.
>
> * LM1881 Video Sync Separator Data Sheet
>   National Semiconductor Corporation
>
> * QuickTime 5 API Reference
>   Apple Computer, Inc.
>
> * Media Composer 1000 User Manual
>   Avid Technology, Inc.
>
>
>
> ____________________________________________________
> Thorsten Froehlich, Duisburg, Germany
> e-mail: tho### [at] trfde
>
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

In article <3cd6d677@news.povray.org> , "PovRAY" <cbd### [at] my-dejacom> wrote:

> I'd be grateful if you can tell me where the feature is in Premiere, because
> I can't find anything which does this.
>
> The closest is "interlace fields" but as I said earlier this interlaces both
> fields of all frames, so you would then have to manually delete alternate
> alternate frames and close up all of the gaps which is very laborious.

Nope, you can use that.  Instructions can be found in this thread:

<http://news.povray.org/povray.beta-test/19628/127824/>

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

> Instructions can be found in this thread:
>
> <http://news.povray.org/povray.beta-test/19628/127824/>

Aha! The Rate Stretch tool. That sounds like it would do the trick. You'd
have to be careful that it removed the *redundant* frames though. I'll give
it a try.

Thanks Thorsten  :)

Colin

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*There* it is! I've been looking for that.

Yeah, the rate stretch tool seems like sort of a hack, but if it works, it
works. I'll trust my past self on this one. =)

- Slime
[ http://www.slimeland.com/ ]
[ http://www.slimeland.com/images/ ]

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