Film->VHS Question

In Film->NTSC_VHS conversions, is the film telecined (to get 29.970fps) and then interlaced? If so, would you deinterlace before or after IVTC'ing?

Wikipedia seems to indicate that all VHSs are interlaced, by design:

Each helical track contains a single field ('even' or 'odd' field, equivalent to half a frame) encoded as an analog raster scan, similar to analog TV broadcasts. The horizontal resolution is 170 lines per scanline, and the vertical resolution (the number of scanlines) is the same as the respective analog TV standard (576 for PAL or 486 for NTSC). In modern-day digital terminology, NTSC VHS is roughly equivalent to 333x480 pixels luma and 40x480 chroma resolutions (333x480 pixels=159,840 pixels or 0.16MP (1/6 of a MegaPixel)).[18], while PAL VHS offers the equivalent of about 335x576 pixels luma and 40x240 chroma (the vertical chroma resolution of PAL is limited by the PAL color delay line mechanism).

No, no.

Read this: http://neuron2.net/LVG/interlacing.html

It's a little outdated, but the info is good.

Good info Moth3r!

Antcufaalb, judging by your question, you haven't fully understood what interlacing is. Interlacing basically refers to how televisions draw an image on older crt television and the artifacts that will show up when you play back TV based material (like VHS tapes) on computer monitors or HD TVs - which are PROGRESSIVE scan monitors.

Remember those two words, INTERLACED and PROGRESSIVE. Basically two different methods for displaying an image on a screen. Interlaced is how older CRT tvs draw - and old camcorders/TV cameras record - an image. Progressive is how a film or a modern digital camera records an image and how a movie theatre or computer monitor or HDTV draws an image. These two methods are VERY different from each other.

So to quickly answer your question, when you IVTC you are reversing the telecine process. You are going from an interlaced image to a progressive image. A telecine is 24P -> 60i and an IVTC is 60i -> 24p. (I say 60i because a TV is not really 29.97 FRAMES per second. An old TV doesn't draw frames, it draws FIELDS in a "venetian blinds" zig zag manner 59.9 times a second, which is what causes that "zig zag" combing on a progressive display monitor)

Do not worry about deinterlacing your project AT ALL. In fact, when you are capturing, be sure your capture isn't deinterlacing it on the fly or you are going to lose fields and thus you will be losing frames.

Deinterlacing is an operation to remove combing and is ONLY useful for stuff that was SHOT on video (like home videos or Saved By The Bell) and then DISPLAYED on a progressive scan monitor like a computer or an HD TV. Of course, the problem is, like the article explains, how can you do this without losing resolution? This is actually a huge headache since we have over 60 years of video lying around (home videos, TV shows shot on video, concerts), and how do we preserve all of this in its fullest quality for the future where crt TVs - who naturally draw their image in an interlaced manner - won't exist anymore?

(merged this comment with the one above)

Thanks for the information, everyone!

Mavimao, you're right: my understanding of interlacing (at the time of the first post in this thread) was poor, at best. Now it's much better thanks to the information that both you and Moth3r provided.

My captures are raw (excluding TBCs, of course). I double-check the settings on all of my equipment and software prior to doing one to ensure that nothing fancy, e.g., noise reduction, is turned on. With each capture, I intend to take pictures and screenshots of the respective hardware and software settings involved so that someone with more experience can correct me if I do something in a suboptimal way.

I might just buy this book. The first edition contains the analog information that was removed for the second.