Video Asylum

Posted by Some Guy on December 09, 2003 at 07:06:02

In Reply to: Re: It's not the disc posted by dave789 on November 26, 2003 at 17:15:35:

>Film is make at 24 frames per second?

Modern film is projected (and generally shot at) 24 frames per second. Most silent films were shot at 16fps, which is why they appear to be moving so fast in some transfers as they didn't show them at the right speed. This has been corrected in most archival sets and DVDs, but I remember in videos from the 70s and 80s almost all of them were shown at a faster speed.

One last digression... film is usually shot faster to show slo motion shots. You can easily tell when it isn't as the motion will be choppy... but yes, generally film is made at 24fps.

>Then movies on DVD has lesser quality than progressive scan signal
>(in term of refresh rate)?

Don't get consfused by the terms... refresh rate is for displays, not for players. It refers to how quickly the monitor can rescan the lines. Movies on DVD are just that... movies on DVD. They are not the height of quality (720x480 is only barely higher than VGA and at the bottom of the HDTV standards) and pale in comparison to film (less color resolution and far less in terms of picture resolution); however, they still look pretty good.

>So do you mean that the progressive scan signal is made up by player
>and that it is not originally on the disc?

Progressive scan can be on the disc. I'd thought most DVDs were encoded with progressive signals, but I could be wrong on that. It's true that pretty much anything shot with a video camera is an interlace source already, but I'd thought that movies were encoded as progressive signals considering that's how they started out (full frame as opposed to fields...)

I've ripped a few DVDs in my time and it appeared to me that the data being pulled off was being pulled off in frames rather than fields in most cases; but, this could also be that the fields are being recombined into fields. My thoughts against this are that I've never really seen any interlace artifacts on the stills, but rather full blur on motion shots... if you've seen still shots of motion on interlaced sources, you'll notice the individual lines of the fields can be clearly identified.

For some more in-depth info, read this VERY informative site:

http://www.hometheaterhifi.com/volume_7_4/dvd-benchmark-part-5-progressive-10-2000.html

This info appears to be from 2000, so I'm not sure if most DVDs are still interlaced or not. With anamorphic transfers now the norm, progressive scan players far more common (remember that they used to cost $700-1000 and regular DVD players in 2000 were at least $200), and HDTV being more than just a toy for the uber-rich, it's quite possible that films are being encoded as progressive on the DVD. I couldn't find anything to verify that, but that's just my deduction.

>Then is there no difference between these two?
>1. player makes progressive signal and digital TV accepts it.
>2. player sends interlaced signal and digital TV makes progressive
> signeal internally (doubles the lines) and displays it.

Well, if an interlaced source, then the only real difference is in what is doing the deinterlacing. Progressive DVD players and digital TVs both have deinterlacers that will convert the signal, but there are always different levels of quality to the process. Just one more thing to consider in the purchase process.

The question then comes in with what happens with a progressive signal... It should logically pass right through to the TV and be broadcast as is, but who knows what really happens?