randomly deinterlaced frames

[mathmax]

thank you for the detailed explanation

In this case the original video is progressive. But some cameras film 50 fields per second, right? In that case, the two field Bt and Bb would not correspond to the same moment. What if we would like to convert such source to NTSC? The order wouldn't be respected, right?

Btw, I don't understand why some source are 50 fields per second.. I think it's always better to play a 25fps film with both fields of the same frame rather than a 50 fps with fields of different images which produce a comb artifact.. Why do some cameras film directly in 50 fps?

I also wonder if the recent TVs with flat screen impose a framerate. They should be able to play NTSC, PAL or 23,976 fps without pulldown or any conversion methods, shouldn't they? Or at least, if they really need a specific framerate, can't they apply the pulldown on the fly? That would avoid to convert the DVD in NTSC or PAL according to the target monitor..

[poisondeathray]

In this case the original video is progressive. But some cameras film 60 fields per second, right? In that case, the two field Bt and Bb would not correspond to the same moment. What if we would like to convert such source to NTSC? The order wouldn't be respected, right?

60 fields per second, interlaced , is 60 moments in time per second . This is already NTSC compatible

Btw, I don't understand why some source are 50fps.. I think it's always better to play a 25fps film with both fields of the same frame rather than a 50 fps with fields of different images which produce a comb artifact.. Why do some cameras film directly in 50 fps?

There are no standard 50 fps progressive sources, unless you're talking about HD

50i is better for motion (e.g. sports broadcast), so BBC Sports broadcasts (e.g. soccer) might be 1080i50

It's 50 fields per second, or 25 frames per second . That is analogous to the 60 fields per second example above. They shoot 50Hz in 50Hz regions

60Hz power grid regions use 60 fields per second (e.g. USA, Canada)
50Hz regions use 50 fields per second (e.g. UK)

25p content is still broadcast as 50Hz stream (each field is same moment in time)

I also wonder if the recent TVs with flat screen impose a framerate. They should be able to play NTSC, PAL or 23,976 fps without pulldown or any conversion methods, shouldn't they? Or at least, if they really need a specific framerate, can't they apply the pulldown on the fly? That would avoid to convert the DVD in NTSC or PAL according to the target monitor..

It depends on the model, because typical refresh rates will be multiples of the power grid. Some have problems with the power source as well (If you buy a TV in UK , it might not work properly in USA)

e.g. USA would be 60Hz/120Hz/240Hz
e.g UK would be 50Hz/150Hz/200Hz

60 fields per second looks normal on 60Hz refresh rate

[mathmax]

60 fields per second, interlaced , is 60 moments in time per second . This is already NTSC compatible

sorry I meant 50 fps. In that case the 3:2:3:2:2 pulldow will not respect the order of the field, right?

There are no standard 50 fps progressive sources, unless you're talking about HD

This time I meant 50 field per second.. and I wondered why they sometimes shoot this way and not 25fps since the first method will give a "comb" effect on screen..

It depends on the model, because typical refresh rates will be multiples of the power grid. Some have problems with the power source as well (If you buy a TV in UK , it might not work properly in USA)

e.g. USA would be 60Hz/120Hz/240Hz
e.g UK would be 50Hz/150Hz/200Hz

60 fields per second looks normal on 60Hz refresh rate

so even with recent TV it's needed to encode a DVD in the right system (NTSC or PAL), right? But why don't we have the same problem on computer?

[jagabo]

sorry I meant 50 fps. In that case the 3:2:3:2:2 pulldow will not respect the order of the field, right?

The pulldown methods are only for progressive sources. It's not suitable for interlaced sources.

This time I meant 50 field per second.. and I wondered why they sometimes shoot this way and not 25fps since the first method will give a "comb" effect on screen..

PAL video cameras shoot 50 at fields per second. Film is shot at 24 frames per second. When you watch interlaced video on TV you see one field at a time so there are no comb artifacts.

[mathmax]

mmm ok.. but why do the computers show both fields at the same time?

[Gavino]

Computer displays are progressive, so interlaced video must be deinterlaced for proper viewing.
As pdr said in post #27:

It depends on what PC software you are using, if you are using dedicated DVD software it should look normal.

[mathmax]

DVD software will deinterlace.. so it'll not be as good as watching on TV, right?

But why can't computers show one field at a time?

[poisondeathray]

DVD software will deinterlace.. so it'll not be as good as watching on TV, right?

But why can't computers show one field at a time?

You can show 1 field at a time, but timing will be off, unless it's a 60i or 50i source (i.e. true interlaced). For an interlaced source each field represents a different moment in time. Also, each field is like a half frame (not all the information of a full frame is there) so it won't look right.

When you bob deinterlace, you are viewing each field resized to a full frame . So for a 60i source, this is viewed as 60p , 60 frames per second

This isn't the same thing as pulldown removal . Pulldown removal will return the original progressive frames . e.g. for a 24p telecined source (24p in 60i) , you get the original 24p frames back - aka inverse telecine

[poisondeathray]

It depends on the software used and hardware used. Not all support 3:2:3:2:2 pulldown

You can look for reviews on your particular model
e.g the denon 1610 fails 3:2:3:2:2 in this review (scroll down to the table)
http://winstonsreviews.com/?page_id=493

There are test discs you can check different cadences and patterns and quality evaluation
http://www.oppodigital.com/blu-ray-benchmark/blu-ray-benchmark-Users_Guide.asp
http://www.hqv.com/index.cfm?page=benchmark

For software players, you have to check to see if it supports that cadence, and also if your graphic card supports it
e.g. this is a review of a GFX card, using power DVD and a test disc for playback . You can see the GT430 fails this pattern, but the HD5570 works ok for 3:2:3:2:2
http://www.anandtech.com/Show/Index/3973?cPage=12&all=False&sort=0&page=4&slug=nvidias...geforce-gt-430

Also, there might be differences between the "hard" method vs. the "soft" method (the hard method is the one encoded as interlaced, the soft is using flags like dgpulldown)

[mathmax]

Thank you. I read carefully your answer but still I don't understand some points:

You can show 1 field at a time, but timing will be off

what do you mean by "timing will be off"? I understand well that a field is half of a frame and I also understand well the bob deinterlace process. But I wondered if a computer could display the same way as a TV, i.e without deinterlacing but showing one field at a time (1 line over 2 will be black if I pause the video).

I've tried to read my file with power DVD and it seems that it removes the pulldown to recover the 25fps progressive video. Well.. that's nice, but I wondered if some softwares are able to display like a TV without pulldown removal.

Or maybe my graphic card doesn't support 3:2:3:2:2 so it applies a pulldown removal instead? My graphic card is the ATI Mobility Radeon HD 5470. Can I download a test disc somewhere to make a test?

I would like to offer the footage to a person living in Japan.. but I don't have information about the hardwares she uses. If I use the "soft" method, her device should pulldown the video according to the flags, right?

[poisondeathray]

Thank you. I read carefully your answer but still I don't understand some points:

You can show 1 field at a time, but timing will be off

what do you mean by "timing will be off"? I understand well that a field is half of a frame and I also understand well the bob deinterlace process. But I wondered if a computer could display the same way as a TV, i.e without deinterlacing but showing one field at a time (1 line over 2 will be black if I pause the video).

The timing will be off for a non interlaced source (like yours), because the fields aren't evenly spaced in terms of timing. A true interlaced source like 60i is 60 moments in time. Yours is 25 moments in time spread out between 60 fields. The pullown patterns are only used for progressive sources, to make them compatible with DVD. The signal is 60i, but the content might not be 60i. For a true interlaced source, both content and signal are 60i. If you deinterlace instead of removing pulldown for the progressive source, the timing will be off (you will get repeats, because they are not decimated). If you view every field separately, it will not be smooth, because pulldown not removed (you have repeats), thats' why timing is off

You mean a CRT TV ? Progressive display needs deinterlacing as explained above, other wise you see combing as in your 1st post

I've tried to read my file with power DVD and it seems that it removes the pulldown to recover the 25fps progressive video. Well.. that's nice, but I wondered if some softwares are able to display like a TV without pulldown removal.

Or maybe my graphic card doesn't support 3:2:3:2:2 so it applies a pulldown removal instead? My graphic card is the ATI Mobility Radeon HD 5470. Can I download a test disc somewhere to make a test?

If it plays back fine with no repeats it probably works ok with your setup
Check those links above for test discs. I think the HQV website might have them

I would like to offer the footage to a person living in Japan.. but I don't have information about the hardwares she uses. If I use the "soft" method, her device should pulldown the video according to the flags, right?

I don't know about Japan, I think they use a different system like NTSC-J or something. There might be other considerations in terms of levels and cadence. Jagabo will know

[mathmax]

The timing will be off for a non interlaced source (like yours), because the fields aren't evenly spaced in terms of timing. A true interlaced source like 60i is 60 moments in time. Yours is 25 moments in time spread out between 60 fields. The pullown patterns are only used for progressive sources, to make them compatible with DVD. The signal is 60i, but the content might not be 60i. For a true interlaced source, both content and signal are 60i. If you deinterlace instead of removing pulldown for the progressive source, the timing will be off (you will get repeats, because they are not decimated). If you view every field separately, it will not be smooth, because pulldown not removed (you have repeats), thats' why timing is off

Ok I understand that.. but I don't want to apply any deinterlacing filter. I would like a software that shows the video as a TV. Well.. Jagabo said there will be no comb artifact on a TV because fields are displayed one at a time. So I thought there might be some players to reproduce the TV behaviour, i.e show an interlaced source without deinterlacing it, without pulldown removal and without comb artifacts. If one field is displayed at a time (without bob deinterlace), that means one line over two must be black for each frame (like on a TV), am I right?

You mean a CRT TV ?

Well.. that's another question I asked above. Is there a difference between flat screen and CRT TV ? I understand that the last one needs to respect the supply frequency.. but the new screens should be free of that constraint, shouldn't they? Flat screen TV should be able to play any rates and even be able to deal with frames rather than fields.

[jagabo]

Bob deinterlacing is about the same thing you see on a CRT TV. The electron beam on a TV is nearly two scan lines thick so each field pretty much fills the face of the CRT.

[mathmax]

Bob deinterlacing is about the same thing you see on a CRT TV. The electron beam on a TV is nearly two scan lines thick so each field pretty much fills the face of the CRT.

oh ok.. but what about LCD TVs?

[jagabo]

LCD TVs perform a simple bob, a smart bob, or IVTC when they can.

[mathmax]

LCD TVs perform a simple bob, a smart bob, or IVTC when they can.

I see So the best way is surely to use 3:2:3:2:2 pulldown in my case.
As I understand it.. if her TV is LCD, it will inverse the telecine process and play it at 25fps.. and if it's a CRT TV, it will display the video field by field.

[jagabo]

LCD TVs perform a simple bob, a smart bob, or IVTC when they can.

I see So the best way is surely to use 3:2:3:2:2 pulldown in my case.
As I understand it.. if her TV is LCD, it will inverse the telecine process and play it at 25fps..

Probably not. Assuming you use pulldown flags instead of hard pulldown:

If the DVD player is sending interlaced video to the TV (eg. they're connected via composite, s-video, interlaced component) the TV will most likely perform a simple bob or smart bob.

If the DVD player is sending a progressive signal to the TV it will duplicate the 25 fps progressive frames to 60 fps and send 1280x720p60 or 1920x1080p60.

and if it's a CRT TV, it will display the video field by field.

Yes.

[mathmax]

Probably not. Assuming you use pulldown flags instead of hard pulldown:

If the DVD player is sending interlaced video to the TV (eg. they're connected via composite, s-video, interlaced component) the TV will most likely perform a simple bob or smart bob.

If the DVD player is sending a progressive signal to the TV it will duplicate the 25 fps progressive frames to 60 fps and send 1280x720p60 or 1920x1080p60.

Why do you say "assuming you use pulldown flags instead of hard pulldown"? Will it be different if I use hard pulldown? What are the advantages of each method? I guess soft pulldown gives a smaller encoded file.. right?

And what if I use the blend method? Will it also play at 60i?

I think that's a pity to loose half of the image to have higher framerate... Why can't the screen play at 25 or 29fps?

[jagabo]

Why do you say "assuming you use pulldown flags instead of hard pulldown"? Will it be different if I use hard pulldown?

When you use soft pulldown the frames are stored progressively. It's easy for the DVD player to scale and duplicate those frames when putting out 60p. DVD players usually aren't smart enough to IVTC video that's been through hard pulldown. Especially with unusual (anything other than 3:2) pulldown patterns.

What are the advantages of each method? I guess soft pulldown gives a smaller encoded file.. right?

File size is simply bitrate * running time. But progressive frames require less bitrate than interlaced frames. So progressive with pulldown flags can be smaller with the same quality, or the same size with better quality.

And what if I use the blend method? Will it also play at 60i?

Yes. No player is smart enough to remove blended fields and reconstruct the original film frames.

[mathmax]

so if I use soft pulldown, the player will have better chance to play at 25fps cause even if it doesn't know the 3:2:3:2:2 pulldown process, it can simply ignore the flags and play it as normal progressive 25fps video, right?

But you said that even with soft pulldown, it will probably send an interlaced video to the TV... is that because most LCD TV require 60 fps interlaced videos?

[jagabo]

so if I use soft pulldown, the player will have better chance to play at 25fps cause even if it doesn't know the 3:2:3:2:2 pulldown process, it can simply ignore the flags and play it as normal progressive 25fps video, right?

It has a better chance of sending progressive frames to the TV. It won't be 25 fps because that's not supported by NTSC systems. It will frame repeated to 60 fps.

But you said that even with soft pulldown, it will probably send an interlaced video to the TV... is that because most LCD TV require 60 fps interlaced videos?

It depends on the connection between the DVD player and the TV. Composite and s-video will always be interlaced. Component and HDMI can be either interlaced or progressive.