What codecs allow you to encode with interlacing

[ThePanda]

Hi, I want to encode a DVD and leave the picture size and interlacing exactly like the original. Is there anything like divx that can do this or can only MPEG2 do it?

[Ookami]

Try the Xvid codec, AFAIK, it supports interlacing... But some of the Xvid gurus should better reply this one, I never tried the interlace + Xvid stuff (I've always deinterlaced).

Cheers,

Mijo.

[kvs]

XviD can encode interlaced stuff as it is, it has a checkbox for it.. I have much less experience with divx 5, but I _think_ you can encode interlaced stuff there as well?

[ulfschack]

What's the point in keeping the interlacing in divX/Xvid ? Are you planning on a stand-alone Mpeg4 player?

cheers

PS This is the first time I realized that xvid is divx backwards !! How stupid am I :)

[ThePanda]

ulf: In my other thread here (http://forum.doom9.org/showthread.php?s=&postid=132357), avih pointed out to me that you may be able to output at DVD-like resolution from your computer, so I thought if you could keep the original resolution and interlacing it might look just like the original when shown on the TV.

[ookzDVD]

@ThePanda,

YES, XviD can do it, encode in interlace mode,
I've encoded in the original resolution,
and the result is good if I see it on TV thru
the TV-out use TV Tool.

PS. Use 640x480 for the TV resolution.

[ulfschack]

But tv-out cards only do progressive, right? I'm quite sure of it. If I'm wrong however, interlaced divx video is highly intersting ... But if I'm not, my point still holds. In the thread you mention it is my understanding that Avih didn't quite get it to work.

cheers

[avih]

the tv card MUST output interlaced, since the tv-set itself is interlaced only.

and if you'll read my post carefully, youll find out that i did have success, but i had problem in keeping the correct field order throughout the playback.

but when it's working, u get 50 (pal) fps, smooth as silk ;)

cheers
avi.

[ulfschack]

Smooth as silk, eh? That's good news :)

I'm still not convinced that pc cards must output interlaced just because TV's are interlaced, tho. Consider progressive DVD films.

You say you had problems maintaining the field order throughout the movie, but why's it changing? Because of dropped frames? Could it be that it's really interlace lines you're seeing now and then? I don't mean to be insulting ... just considering alternatives s'all ;)

cheers

[avih]

i didn't investigate this issue thourully. i saw it's possible to get smooth playback. that was enough for me atm. as i said, it might be cpu load related, dropped frame related, inaccurate clocks, etc.

you're welcome to do more tests and submit your results. i'll be happy to try a solid solution. but i don't have time for testing, and i'm occupied with other subjects atm.

cheers
avi

[temporance]

You don't need interlace support in the codec to encode interlace. Any codec will encode interlaced material but will use a lot more bits if it is not optimised (e.g. with MPEG-4 interlace tools).

It sounds like it's possible to reconstruct the interlaced output precisely at the PC's TV-out. What video card does this?

[Zhnujm]

even a progressive dvd is displayed interlaced on a tv. of course you cannot see this because both fields contain the same frame of the dvd.
a progressive display on a tv is only possible if you half the vertical resolution.
as avih said in the other thread all you need is the right resolution (XXXx480 for ntsc, XXXx576 for pal) and tvtool to activate the fullscreen mode. thats true for nvidia cards.
and you really really dont see interlace artifacts. ;)

[ulfschack]

Well, methinks this is great news. It's just that I've heard so many opposing claims to this. Thus my negativity.

I'd also suspected that DVDs split the prog frames in order to deliver what the TV wants, but that's kind of "cheating" ... hear me out. Assusme (in the interlaced instance) that the TV-card does the same and tries to split a full frame (that is really two interleaved fields) like it would a progressive one. That would surely mess things up in at least half the cases.

My problem is that I've never managed to get TVtool to work on full screen, (only that 5% one.) But if both you and Avih have gotten it to work there's no point in continuing arguing about it :)

a'll bee baak ... after some experimenting.

cheers

[zeb7]

I've had Interlaced working for well at lest a year , i think the main reason you all having trouble is
with hardware TVout , the ones that have black boarders with a 640x480 image in the middle
are not suitable ( TVtool hack may help but i've never attempted it)

Matrox TVout is the right type 720x576 PAL out (the DVDMAX feature)
But it outputs the upper field order which is the opposite of just about every other
device on the planet !

TheXcard ,DV and most capture cards use lower field

If you are unlucky owner of Matrox capture card (like me)
and want you Divx to playback on the Xcard ,
You need the use Smartdelacer plugin with VirtualDub
set to Field swap before phase shift / Phase shift / Disable motion processing
(the Divx will not play correctly though the matrox TVout but it will work on the Xcard)

Bitrates are higher because the use of interlaced prediction is not good.

check out the Smartdelacer read me /help file for a discription of field order

[temporance]

In an the future, the MPEG-4 field "top_field_first" will sort these devices out. If you're encoding interlaced video, your codec should set top_field_first=1 if the top field of every frame should be shown first.

"top_field_first" is what hardware DivX players will look at.

[zeb7]

Temporance thank's , has this new feature been discussed at Divx.com ?
Any more info would be appreciated thanks ,
But its a little more complex as Divx(or MPEG4 its self) is not optimized for working on singe fields
but working on the two fields as one progressive frame which contained a high amount
of vertical detail
I read somewhere that MPEG4 supports interlace natively, not as two separate fields as with MPEG2 and
MJPEG codec's
I guess it wont be long before we have full interlaced support as Divx programmer's seem to be a hardworking decent bunch .


There are two reasons for using "top field first" setting
1 A 3D anim rending set to top field first in the 3D software
2 The Capture Card capture with top field first (Matrox)


Number 1 is easy , It should be encoded with top field first
Number 2 is different ,depending on its Analog source.

2.1 If the Source is Camera (home video) and edited with top field first
then it also should be encoded with top field first

2.2 If the Source is captured from a TV show and that TV show was originally edited with lower field first
then all the scene changes will be out of phase (needing 3 I-frames instead of 1 )
further more their is sometimes an unnecessary increase in interlacing which result's in higher bitrates
when progressive video (edited/broadcasted as Lower field) is capture as top field first (matrox cards)

Basically Matrox cards are the problem.

[avih]

@zeb7
i can offer 2 suggestions for the out-of-order field display for your card.

1. use zoom player at full screen, you can move your image in every direction. (so move it up or down 1 pixel).

2. divxg400 has such feature for cards that output the wrong order. it's a filter that will work with most codecs. (and has other tv-related options as overscan etc).i think it was initially designed for matrox cards, but it's a general solution now.

cheers
avi

[zeb7]

I didn't know zoom player was so flexible ,
And i'll upgrade to the latest divxg400 to see what's available

i can continue making Xcard compatible video , and use the hacks
above when the video needs to go though Matrox TVout,

Thanks, avih