How can I make interlace work for me?

[kearlywi]

I've read EADFAG on this site several times, and I have read other guides, and I have been encoding (for private use, I'm not a devil worshiping fansubber ) for about 8 months now.

Its no lie to say I've learned a tremendous amount about video in my time working with it the last 8 months, but recently, something came to me. I ALWAYS DEINTERLACE. I hadn't really thought of it before, since most of the time my DVD ripped footage (after being processed by dvd2avi) looks really terrible with Interlace lines in it. Why is it that these horrible looking Interlace lines were invisible to the naked eye on a normal DVD? (If you watch a dvd frame by frame you can still catch them, barely, in some cases).

Now some of you might be saying, why keep the interlace? Interlace essentially doubles the number of frames in a sense by causing frames to change one half frame at a time, first all the odd number lines go then all the even ones (I think). When you deinterlace, the interlace "lines" are then replaced a blurred area. You often wont notice the difference between Interlaced and Deinterlaced, but in some cases, where there is very fast movement, deinterlaced will seem a lot less fluid (at least in my experience). I'm finding that fluidness is something that is lacking in my encodes lately. I'm up very late, and its possible I made some mistakes in this post, but if anyone can tell me why Interlace is so much nastier after ripping/processing than before I would greatly appreciate it.

[Zarxrax]

On a television, Interlacing is not usually visible to most people. This is why interlacing was used in the first place. If people could have saw it, it wouldn't have been used. When you playback on a dvd player on your pc, the dvd software deinterlaces it.

[Scintilla]

I'm finding that fluidness is something that is lacking in my encodes lately. I'm up very late, and its possible I made some mistakes in this post

Yeah, like the fact that the proper word is "fluidity".

[kearlywi]

Thank you Zarxrax for that bit of information. If computer DVD software(and I'm assuming standard DVD players, since interlace lines dont tend to show on those either) deinterlace footage, then does Television also Deinterlace, or is Interlace something just for Television? If so that would explain why I have never gotten interlaced footage to look good on my pc.

Yeah, like the fact that the proper word is "fluidity".

Somebody call Absolute Destiny. He's an English Teacher, FYI. I looked into it and I'm pretty sure both usages are correct, but then again, I literally DID ask somebody to find a mistake in my post, but I wasnt reffering to grammatical ones.

[Scintilla]

Somebody call Absolute Destiny. He's an English Teacher, FYI. I looked into it and I'm pretty sure both usages are correct, but then again, I literally DID ask somebody to find a mistake in my post, but I wasnt reffering to grammatical ones.

Yeah, and while you have his attention, perhaps you could get him to answer the interlacing question as well.

I withdraw the objection. According to http://dictionary.reference.com , both forms are correct.

[Scintilla]

Thank you Zarxrax for that bit of information. If computer DVD software(and I'm assuming standard DVD players, since interlace lines dont tend to show on those either) deinterlace footage, then does Television also Deinterlace, or is Interlace something just for Television? If so that would explain why I have never gotten interlaced footage to look good on my pc.

The way I understand it is: Normal NTSC TVs display at 59.94 fields per second, interlaced. DVDs are interlaced because of this, so that the TV can display them properly. But computer monitors only do progressive (have no conception of fields and so can't alternate them like the TV does), so DVD software has to deinterlace.

Somebody correct me if I'm wrong.

[Ashyukun]

SD (standard definition) NTSC TV is interlaced, IIRC originally because it allowed the effective halving of the bandwidth/resolution required for the transmission of the television signal compared to doing it progressive (updating the entire picture at the same time). Many (if not all) HDTVs and all computer monitors operate in what is referred to as 'progressive scan', updating the entire screen at once (not really, but it works for this description). Most DVDs (R1s, at least) are 29.97fps interlaced for playback on NTSC televisions. Some however (which we tend to drool over when we come across them) are encoded in 23.976fps progressive with a flag for the DVD player's decoder to take care of the conversion to interlaced itself if being displayed on a standard NTSC TV or to just output the progressive film if played back on a device (HDTV, computer) capable of displaying progressive video. When playing an interlaced DVD back on a computer screen, I believe that the software does take care of the de-interlacing.