lines on mpeg2 playback [see pic]???

[the_doc735]

lines on mpeg2 playback [see pic]???

anyone know what causes this and how to fix it please? (these lines 'cycle' every third or fourth frame)

[zoobie]

those comb lines?
that's normal and won't be seen on tv playback
notice it's only on large movement

[jman98]

We see this in the USA on PAL -> NTSC conversions. zoobie is right that this is not seen on TV playback. I would guess that you are either watching an American DVD that suffers from PAL -> NTSC conversion or perhaps even an NTSC -> PAL conversion could do this on a region 2 DVD, but I don't know for sure.

[the_doc735]

those comb lines?
that's normal and won't be seen on tv playback
notice it's only on large movement

yes it is only on large movement! - how did you know that?

as long as the TV is OK - that's fine! - looks a bit rough on the computer though, i.e. WMP or Power DVD! - don't suppose there is much I can do about that though?

[the_doc735]

We see this in the USA on PAL -> NTSC conversions. zoobie is right that this is not seen on TV playback. I would guess that you are either watching an American DVD that suffers from PAL -> NTSC conversion or perhaps even an NTSC -> PAL conversion could do this on a region 2 DVD, but I don't know for sure.

I used 'DVB viewer' to capture the transmission from 'channel 4' [UK TV station] with a 'nova-t 500' freeview card. I think it came up in 'tmpgEnc express 4' as 1:1 aspect ratio? I outputted it to -> 16:9.

[zoobie]

the VLC player has a few options to remove it while viewing
bob and discard

[edDV]

All it shows is the people were in motion. You only want stills?

Interlace video records odd lines in one time sample and even lines 1/50th second later.

Interlace TV sets play fields sequentially. All is fine. Computers show two fields at once. Computer players often deinterlace. Progressive DVD players or progressive TV sets usually do a better job at deinterlace.

[hanugro]

Did you resize the frame? You need to deinterlace before resizing but it will prolong render time.

[jagabo]

Each frame of interlaced video contains two separate half-pictures. When you watch these on a normal TV you see one half-picture at a time:



On a progressive computer monitor you see both at the same time unless you are using a player that deinterlaces.

[PuzZLeR]

Not to be mean, just so you understand - your problem is the same thing as saying that "my dog barks". There is nothing abnormal about what's going on.

Interlacing is a 1930s technology to handle the minimal bandwidth back then, that, unfortunately, we're still living with today even if conditions are so much better. Most TVs can handle it since they were designed to expect it, but later models and PC monitors show its limitations.

However, there are several players that deinterlace on playback, even software players like VLC, quite easily (as was pointed out earlier).

If you permanently want to get rid of those lines, you'd have to re-encode, and that would be not only a separate thread, but a series of them.

[PuzZLeR]

Jagabo:
Impressive how you separated the fields in your post...

[jman98]

Jagabo:
Impressive how you separated the fields in your post...

I thought so too. Jagabo - you da man!

[jagabo]

Nah, it's easy. Long ago I made an image with single pixel thick, horizontal, alternating black and white lines (specifically for this purpose). I use it as a mask in an image editor (making white the transparent color). All I do is overlay the mask on the interlaced image. The black lines, being opaque, obscure one field, the white lines, being transparent, allow the other field to show. By moving the mask up or down I can show one field or the other. Then I converted the pair to an animated GIF.

[edDV]

...
...
Interlacing is a 1930s technology to handle the minimal bandwidth back then, that, unfortunately, we're still living with today even if conditions are so much better. Most TVs can handle it since they were designed to expect it, but later models and PC monitors show its limitations.
...

Interlace is a fact of video life unless you confine all your viewing to progressive DVD and only 720p broadcasts.

Normal 480i NTSC is interlace, as is ATSC 480i
Normal 576i PAL is interlace, as is DVB 576i

1080i is also interlace for the very same reason interlace was used in the 1930's. You get 1/50 or 1/60 second motion updates while using half the bandwidth of 1080p. This keeps motion smooth for "live" TV and for film, all information is transmitted to allow inverse telecine back to 1080p/24fps when the TV or DVD player containes "cinema" inverse telecine processing*.

If interlace wasn't used for broadcasting, we would either have half the channels, or TV frames would be ~half the pixel size as is the case with 1280x720p vs. 1920x1080i.

Interlace is a great thing. Learn to deal with it.


* Let me re-emphasize that point. 1080i transmits ALL the information needed to display 1920x1080p film at 24fps just as 480i has all the information needed to display 720x480p film at 24fps. Actual display uses frame repeat or frame interpolation to 50.0, 59.94 or ~120 frames per second to avoid flicker.

_

[jagabo]

Interlace is a great thing.

No, it sucks. I'd rather have half the channels.

[edDV]

Interlace is a great thing.

No, it sucks. I'd rather have half the channels.

It is what it is. Bandwidth has been allocated. Done deal.

[Midzuki]

jagabo wrote:

edDV wrote:

Interlace is a great thing.

No, it sucks. I'd rather have half the channels.

I agree. Over 90% of all that's been broadcast since "sometime before 1940"
is nothing less and nothing more than garbage.

[edDV]

jagabo wrote:

edDV wrote:

Interlace is a great thing.

No, it sucks. I'd rather have half the channels.

I agree. Over 90% of all that's been broadcast since "sometime before 1940"
is nothing less and nothing more than garbage.

Progressive DVD + ESPN-HD/ABC-DT/FOX-DT is a valid lifestyle.

[the_doc735]

Nah, it's easy. Long ago I made an image with single pixel thick, horizontal, alternating black and white lines (specifically for this purpose). I use it as a mask in an image editor (making white the transparent color). All I do is overlay the mask on the interlaced image. The black lines, being opaque, obscure one field, the white lines, being transparent, allow the other field to show. By moving the mask up or down I can show one field or the other. Then I converted the pair to an animated GIF.

hey! ...could I get a copy of your 'mask' tool please? [too stupid to make one]

[jagabo]

Nah, it's easy. Long ago I made an image with single pixel thick, horizontal, alternating black and white lines (specifically for this purpose). I use it as a mask in an image editor (making white the transparent color). All I do is overlay the mask on the interlaced image. The black lines, being opaque, obscure one field, the white lines, being transparent, allow the other field to show. By moving the mask up or down I can show one field or the other. Then I converted the pair to an animated GIF.

hey! ...could I get a copy of your 'mask' tool please? [too stupid to make one] :?

It's just a 720x480 BMP file. You may need to manipulate it a bit to make it into a mask. In PhotoImpact, after importing the BMP as an object, I right click on the object and select Properties. One of the attributes is transparency. I make white transparent. Other program will work differently.

interlace_mask_720x480.zip