CurtPalme.com Home Theater Forum

atotaldoofus · Joined: 22 Jun 2009 Posts: 66

But even if an NTSC DVD's content is stored at 24 frames per second, they are played back at 29.9 frames per second, not the 24 that the guide assumes. And if I were playing a PAL DVD, then wouldn't I set the refresh to 50hz instead of 48hz since PAL DVD's are encoded at 25 frames per second? So I don't get the author's logic in selecting 48hz, and just wanted to make sure I've figured this out correctly before I proceed.

Thanks.

Mark_A_W · Posted: Sun Aug 02, 2009 6:08 am Post subject:

Film based NTSC dvds are only played back at 29.9 fps as old US TV's would only run at 60hz.

If you are watching NTSC films, use 48hz.

If you are watching PAL, use 50hz.

But what is your source?

ecrabb · Posted: Sun Aug 02, 2009 6:19 am Post subject:

What guide? What's your source? What is the source content?

While an NTSC film-source DVD content may be 24fps (23.976, actually), encoded at 29.97, it doesn't have to displayed that way. Depending on the actual source content, the display's refresh rate and whether the player is doing inverse telecine (or not), it is NOT necessarily automatically played back at 29.97.

For instance, if you use a software DVD player app, and your display refresh is set to an even multiple of 23.976 (47.952, 71.928), then the 24fps content on the DVD will be played back smoothly with no judder or frame-rate mismatch at the native 24fps film frame rate.

OTOH, a video-source DVD (say, a DVD from ESPN of a World Series game or something) would likely be shot and encoded 59.94i - and should be displayed that way. That's why some guys have multiple setups, so depending on what kind of content they're watching, they switch between 48p or 60p.

Yes, you would use 50hz (instead of 48) for PAL discs.

SC

ecrabb · Posted: Sun Aug 02, 2009 6:20 am Post subject:

Doh! You posted while I was writing, Mark!

SC

atotaldoofus · Joined: 22 Jun 2009 Posts: 66

So my DVD software isn't automatically converting it to 29.97? Okay - I just figured that it would, or that something somewhere else in the chain would (DVD player, DVD decoder codec, hardware video output, etc.)

I wish I'd just bought all my DVD's in PAL to begin with. Razz

Okay, thanks, bye!