alternative lines in pal picture?

Brian

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When I play back a program recorded off TV frame by frame I noticed
that when the picture fades I get lines of one picture mixed with
lines of another picture.
This also happens when there is sudden movement or the camera is
spanning.
My setup is feeding the video from the TV tuner to a analog to digital
converter then into the firewire. The video signal is PAL.
I noticed this program when trying more than one video editor such as
Ulead Video Studio 8.
Is there a setting to help overcome this problem?

Regards Brian
 

Nelly

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What you are seeing is the effect of INTERLACING. In PAL the picture is made
up of 25 frames per second, but each frame consists of two FIELDS - PAL
plays at 50 fields per second.

Although PAL has 625 lines, not all of them carry picture information. Some
carry technical information. Anyway, PAL contains roughly 525 lines of
ACTIVE picture information, but split into two fields each of 312.5 lines.
These two fields are INTERLACED to create a full frame.

So, when there is a sudden transition or a fade, it is possible that one
field will contain the final image from Scene 1 and the next field contains
the first image of Scene 2. And this will produce the effect you are seeing.

I believe there are ways to convert from interlaced to progressive images,
but I don't know how to achieve this. Someone far cleverer than I will
probably be able to tell you!

Nelly

Why do we have interlacing...? In the early days of television the circuits
were too slow to cope with progressive scanning at "high resolution" so
interlacing was a clever work around.

"Brian" <bclark@es.co.nz> wrote in message
news:vvpic0dueghcg0ob6ekfiagimtbqsuq22e@4ax.com...
> When I play back a program recorded off TV frame by frame I noticed
> that when the picture fades I get lines of one picture mixed with
> lines of another picture.
> This also happens when there is sudden movement or the camera is
> spanning.
> My setup is feeding the video from the TV tuner to a analog to digital
> converter then into the firewire. The video signal is PAL.
> I noticed this program when trying more than one video editor such as
> Ulead Video Studio 8.
> Is there a setting to help overcome this problem?
>
> Regards Brian
>
 

Rio

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> Is there a setting to help overcome this problem?

This is not a problem, this is INTERLACED PAL video.
If you look it on a computer monitor you'll see these lines, playing it back
on a PAL TV set will look perfect.
If you don't want it to be interlaces then try to find some deinterlace
plugin for your editing software, but I whouldn't use it...

--
rIO.sK
www.officineitalia.it
 
G

Guest

Guest
Archived from groups: rec.video.desktop,alt.video.dvd.software (More info?)

> When I play back a program recorded off TV frame by frame I noticed
> that when the picture fades I get lines of one picture mixed with
> lines of another picture.
> This also happens when there is sudden movement or the camera is
> spanning.
> My setup is feeding the video from the TV tuner to a analog to digital
> converter then into the firewire. The video signal is PAL.
> I noticed this program when trying more than one video editor such as
> Ulead Video Studio 8.
> Is there a setting to help overcome this problem?
>
> Regards Brian

As others have mentioned, this is just the effect of Interlaced video on a
progressive display. If you are encoding to DVD or SVCD, you should leave it
interlaced for correct playback on your TV. If it's for viewing on a PC
monitor, you are better of deinterlacing it. This is a way to
blend/interpolate between frames or fields to create a progressive image
with no interlacing lines.

If you are going to be working with video in the future, it would be a good
idea to look up the term interlacing on the web and get your head around how
it works. Inverse Telecine might also be a process you would benefit from
reading up on. It is less relevant for PAL than it is for NTSC, but still
worth understanding.
 
G

Guest

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Archived from groups: rec.video.desktop,alt.video.dvd.software (More info?)

I user Premiere Pro with DV video from my camcorder. In the preview window
it doesn't seem to show both fields, by default anyway... It seems to show
one field for each frame that I look at but I'd like either to be able to
advance through video field by field, or to see both fields at once when
viewing a frame.

Am I just stupid and missing something here? What do I have to do to be able
to use individual fields as an individual unit?

"Adam H" <dfghjkl@fghjkl.ur> wrote in message
news:cac67h$597$1@hercules.btinternet.com...
> > When I play back a program recorded off TV frame by frame I noticed
> > that when the picture fades I get lines of one picture mixed with
> > lines of another picture.
> > This also happens when there is sudden movement or the camera is
> > spanning.
> > My setup is feeding the video from the TV tuner to a analog to digital
> > converter then into the firewire. The video signal is PAL.
> > I noticed this program when trying more than one video editor such as
> > Ulead Video Studio 8.
> > Is there a setting to help overcome this problem?
> >
> > Regards Brian
>
> As others have mentioned, this is just the effect of Interlaced video on a
> progressive display. If you are encoding to DVD or SVCD, you should leave
it
> interlaced for correct playback on your TV. If it's for viewing on a PC
> monitor, you are better of deinterlacing it. This is a way to
> blend/interpolate between frames or fields to create a progressive image
> with no interlacing lines.
>
> If you are going to be working with video in the future, it would be a
good
> idea to look up the term interlacing on the web and get your head around
how
> it works. Inverse Telecine might also be a process you would benefit from
> reading up on. It is less relevant for PAL than it is for NTSC, but still
> worth understanding.
>
>
 
G

Guest

Guest
Archived from groups: rec.video.desktop,alt.video.dvd.software (More info?)

> I user Premiere Pro with DV video from my camcorder. In the preview window
> it doesn't seem to show both fields, by default anyway... It seems to show
> one field for each frame that I look at but I'd like either to be able to
> advance through video field by field, or to see both fields at once when
> viewing a frame.
>
> Am I just stupid and missing something here? What do I have to do to be
able
> to use individual fields as an individual unit?

Let's say your source is 720x576 @ 25 fps. It is possible to "un-weave" the
interlaced frames and get a progressive 720x288 50 fps file, but there is
really no point in doing that, as interlaced is the original format, and
that is how video is displayed on a television. Maybe I misunderstood what
you want, or maybe you are not sure what interlaced is all about. What
exactly is it you are trying to achieve?
 

Brian

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"Adam H" <dfghjkl@fghjkl.ur> wrote:

>> When I play back a program recorded off TV frame by frame I noticed
>> that when the picture fades I get lines of one picture mixed with
>> lines of another picture.
>> This also happens when there is sudden movement or the camera is
>> spanning.
>> My setup is feeding the video from the TV tuner to a analog to digital
>> converter then into the firewire. The video signal is PAL.
>> I noticed this program when trying more than one video editor such as
>> Ulead Video Studio 8.
>> Is there a setting to help overcome this problem?
>>
>> Regards Brian
>
>As others have mentioned, this is just the effect of Interlaced video on a
>progressive display. If you are encoding to DVD or SVCD, you should leave it
>interlaced for correct playback on your TV. If it's for viewing on a PC
>monitor, you are better of deinterlacing it. This is a way to
>blend/interpolate between frames or fields to create a progressive image
>with no interlacing lines.
>
>If you are going to be working with video in the future, it would be a good
>idea to look up the term interlacing on the web and get your head around how
>it works. Inverse Telecine might also be a process you would benefit from
>reading up on. It is less relevant for PAL than it is for NTSC, but still
>worth understanding.
>
Thanks Adam and others for the info.
If I were able to find a way to deinterlace the picture would there be
any disadvantage when viewing on a TV?

Regards Brian
 
G

Guest

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Archived from groups: rec.video.desktop,alt.video.dvd.software (More info?)

> Thanks Adam and others for the info.
> If I were able to find a way to deinterlace the picture would there be
> any disadvantage when viewing on a TV?

Yes, there could be a huge disadvantage to this. Basically, interlace is a
technique that "fakes" the smoothness of 50fps on a 25fps television. If you
deinterlace something that was originally interlaced, you basically lose
half the smoothness of the motion and you are also likely to introduce
unnecessary blurring or blending.

You should only ever deinterlace material that is meant to be viewed on a PC
monitor or for VCD. Most MPEG2 players on the PC will perform real-time
deinterlacing anyway.

Like I said in a previous post, if you are serious about producing quality
encodes, you need to understand the terms interlace and IVTC completely.
It's not particularly complicated, you just need to get your head around a
few things. Try and play around with interlaced (video) and progressive
(film) sources and see what effect deinterlacing and IVTC have on them,
particularly scenes with a lot of motion.

As a general rule, material that are produced on film, such as movies,
dramas, cartoons, music videos, etc, should be Inverse Telecined, as they
were originally progressive material.

Things that were filmed on video, such as the news, sports, talk shows, etc,
should be left interlaced, or if it's intended for DIVX on a PC, they should
be deinterlaced. A cool alternative to deinterlacing is to convert it to a
50fps progressive video. That looks really nice on a PC, and maintains all
the smoothness of the original, but is completely useless on a regular TV.