Why deinterlacing my DV movie ?

[schmuh]

Greatings,

After reading many topics in this so helpfull forum:D, I am now confused between the conversion process of my interlaced DV movies.

I read (and experimented) many topics about deinterlacing and this topic is NOT a question about HOW TO deinterlacing.

What are the problem of just converting this interlaced DV to an interlaced DivX:
-Can't I do that
-Do I have a not so compressed DivX
-Do I have a terrible quality loss
-Do I have a problem to render this on my PC
-Do I have a problem to render this on my TV

Thanks for reading

[jggimi]

Hello, and welcome to the forum.What are the problem of just converting this interlaced DV to an interlaced DivX:
-Can't I do thatYes, recent releases of DivX 5 support interlaced encodings.-Do I have a not so compressed DivXI've not done this with the DivX codec, but with other technologies supporting interlaced encoding, the fields are encoded separately. The compressibility will be impacted slightly, but I've never done objective tests to determine exactly how much.-Do I have a terrible quality lossNo, but playback is limited to interlaced devices -- see my next two answers.-Do I have a problem to render this on my PCYes. You will not be able to view your DivX without artifacts, unless you deinterlace on-the-fly during playback, assuming your player can do this (such as with ffdshow). You will usually get better results if you do this during DivX encoding rather than during playback.-Do I have a problem to render this on my TVThe purpose of encoding interlaced is for playback on an interlaced device, such as an analog TV.

[schmuh]

Thanks for your fast and very clean answer to my questions.

I am surprised that no software can emulate a poor interlaced TV set :devil:

What the eyes are seing (Read 11 as 1 this is only for presentation purpose) on a TV is :
_11ee33ee55ee77ee
_ee22ee44ee66ee88
can be doubled to (I completed "e-holes" equally from each "sides")
_1113333555577779...
_0222244446666888... (The "0" can be "2" as its only 1/50fps)
==> Of course, if I pause on an image I will be disapointed by its interlaced structure but this is not the way I usually see movies...

This should allow for better quality as understood by my poor brain.
==> Anybody has any advice about this:
-Why not to do it because it is known as *problem_name_here_please* ?
-How to do it on the fly anyway (Any known renderer) ?

[theReal]

What you describe here is a simple blend deinterlace. It's easy to do and many programs can do it.
However it's not the perfect picture because interlaced video isn't one still picture divided in two halves and then shown as interlaced fields (well, it is when it was converted from film to 50Hz PAL, but it is not when it was shot on interlaced video).
Interlaced video is 50 complete, single, frames per second - each frame with half spatial resolution. In fast movement, field 1 shows a completely different scene than field 2 - if you just blend field 1 and 2 you'll get a mix of two different pictures which results in "ghosting" (objects are doubled and seem transparent).

Really good deinterlacing needs quite some cpu time and can't be done on the fly (at least on most computers).
Fields must be analyzed to see if a simple blend is ok, or if one field should be duplicated or discarded or whatever... I'm not an expert on this, all I know is that some people on this forum have been programming for years to achieve the most perfect deinterlacing - yet there is no 100% perfect deinterlacing.

If you're interested, http://www.100fps.com is a good site. It also offers nice solutions on how NOT to deinterlace and still get perfect PC viewing (50fps video).

[DaveId]

its that your hardware (monitor) is non-interlaced, and probably does not support a 60hz/interlaced refresh rate.. ffdshow is capable of de-interlacing video on playback and is a directshow filter (meaning it can be used in most any media player software)...
so the answers might be - if you want to playback on a television primarily do not deinterlace, if you want to playback on a monitor primarily deinterlace when encoding your video.
however, if you want to playback on a television outputted THROUGH your computer, i would recommend deinterlacing, as most tv-out video cards interlace the output video for the tv, meaning my captures of television episodes are deinterlaced and playback fine on the monitor and television using my computer. however film footage (24p) would only look good on the monitor with a refresh rate close to a multiple of 24 (currently mine supports a nice 75hz which makes movies playback smoothly) because the television lags the motion to compensate for the fewer frames, and it looks choppy...
but i always deinterlace unless my intension is for a mpeg2 file for dvd or vcd playback on televisions with hardware players.
and even then, i contemplate deinterlacing.... it would allow for better video compression (higher quality) and people are getting hdtvs which to the best of my knowledge mostly support 24fps and other refresh rates..
hope this clarifies more than confuses.
dave

[schmuh]

It sounds like keeping it interlaced is the easiest method:
1/ Rip, Edit and Compress
Ripping (To type2 using WinDV adviced at www.doom9.org/dv/guide_paragraph0.html) to my VirtualDubMod XviD platform, you can compress 25fps interlaced DV to 25fps interlaced DivX with a good ratio quality (www.100fps.com is definitely a good ref thanks ;) )
A 2pass encoding with 1 hour per 700Mo sounds good enough...

2/ Watch it on a TV (50hz interlaced)
You can burn 1h of movie on a moneyless CD and offer it to your family for them to watch it on TV on any DVD/DivX reader (Please don't ask my 93 years old grandma to modify the aspect ratio)

3/ Watch it on your PC (75Hz progressive)
You can still watch it on a PC assuming it can handle deinterlacing on the fly (through ffdshow filters for example) using a basic method (Like Doubleframerate to 50fps with no motion blend for fastness)

==> I do not see any problem with this in term of movie quality (Of course, if I pause on an image, I will see those artifacts) ?

[E-Male]

well, why don't you just do it?

[schmuh]

I would like your great experiences to tell me if not deinterlacing is a big deal in term of quality as described in my previous posts.

[communist]

Originally posted by schmuh
I would like your great experiences to tell me

Hehe everyone has a different experience regarding deinterlacing - for ex. I never had to deal with hybrid material / blended fields and other difficult to deinterlace stuff since I mostly encode from PAL DV :D while others mainly do Anime = the most difficult to deinterlace / decomb stuff. Also some like perfect motion throughout the whole encode and will go the extra miles and create complex avisynth functions to get it right while others dont mind a jerky panning / camera movement here and there. It boils down to that you'll have to find out for yourself what you like and what you can accomplish though we can only *suggest working solutions* that we like.

Originally posted by schmuh
tell me if not deinterlacing is a big deal in term of quality as described in my previous posts.

Its more of a big deal to new users - "What?! Throwing away frames /fields - isnt that bad?! Blending them - its too blurry ?!?"

Once you get used to it - its *all well*. Just pick for what you're encoding (PC / TV) and then deinterlace or not. You can even encode it interlaced with DivX / XviD etc. and then deinterlace it on the fly with ffdshow - which is what I do quite often and I didn have too much problems with it yet. Of course deinterlacing during decoding requires some extra CPU power so you may want to encode it deinterlaced if you're not sure on what kind of PCs you will watch it and whether they're fast enough for it.

Just try it out on short DivX / XviD clips or directly with your DV movies -> install ffdshow and let it decode DV (DVSD), then enable deinterlacing and pick a method and see what works best for your eyes :)