FORUMS: list search recent posts

Frame Rate When Ripping DVDs?

COW Forums : Apple Final Cut Pro Legacy

<< PREVIOUS   •   FAQ   •   VIEW ALL   •   PRINT   •   NEXT >>
Bobby Hall
Frame Rate When Ripping DVDs?
on Feb 10, 2017 at 7:45:49 am

I'm editing a reel consisting of movie scenes from DVDs and I have some questions about frame rates. As I understand it, when a 24 fps film is put on DVD, it's first slowed down to 23.976 fps and then 2:3 pulldown is used so it can be played properly on a TV. So when a 24 fps movie is put on DVD, is the video file of that movie 23.976 or 29.97? Is the pulldown implemented to the film on the DVD itself or is it the player or TV that does the pulldown?

I want to make sure that I'm selecting the correct frame rate when I'm ripping footage from a DVD.

Also, out of curiosity, how can 29.97 frames be displayed in one second? That's just a theoretical number, right? Doesn't that just really mean that 2,997 complete frames are displayed in 100 seconds?

Thanks for any info!


Return to posts index

jerry wise
Re: Frame Rate When Ripping DVDs?
on Feb 10, 2017 at 3:38:53 pm

about 29.97 frame rate, i would Google "drop frame timecode vs non drop frame" and that will explain things better.


Return to posts index

Dave LaRonde
Re: Frame Rate When Ripping DVDs?
on Feb 10, 2017 at 3:45:12 pm
Last Edited By Dave LaRonde on Feb 10, 2017 at 3:58:42 pm

A film frame rate file on an American DVD is 23.976. The DVD player is smart enough to add 3:2 pulldown. So if you rip a 24p DVD, keep that in mind.

29.97 doesn't mean that 0.03 of a frame is chopped off once a second. It's a measure of TIME. Think about this:

Europe has 25fps. How long is each frame displayed? 1/25 of a second. The USA has 29.97 fps. How long is each frame displayed? 1/29.97 of a second.

The fraction is messier than it is in Europe. But they're both measures of time.

And why is it that way? Blame the National Television Standards Committee (aka NTSC). Back in the early '50's, they wanted to figure out how to transmit & receive color video without making existing B&W sets obsolete. They needed a tiny bit more information, but the bandwidth of a TV channel was already chock-full. Something had to give. And it was the frame rate.

So since 1953, American TV has been 29.97 fps instead of the original 30 fps.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index


Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 10, 2017 at 10:46:16 pm

Thanks Jerry and Dave!

So if I rip a 24 fps movie DVD, I should rip it at 23.976 to have the frame rate that's stored on the DVD? If I rip it at 24 fps, will it slightly speed up the movie to make it the exact same length as the original film? And is there any downside to doing this? Would that technically alter the audio pitch at all?

Also, in case I want to use the footage in a 29.97 fps timeline in FCP, would I rip the 24 fps DVD footage at 29.97? Or would that just create duplicate frames?


Return to posts index

Nick Meyers
Re: Frame Rate When Ripping DVDs?
on Feb 11, 2017 at 1:15:00 am

i'd always rip with the original frame rate.
deal with it later if you need to, when it is in a better format, like Prores.

changing the frame rate while ripping would most likely just drop or add frames.

"Also, in case I want to use the footage in a 29.97 fps timeline in FCP, would I rip the 24 fps DVD footage at 29.97? Or would that just create duplicate frames?"

yes. that's FCP's way.
not very good.

i've never had to deal with this situation, living in PAL land,
but if i had to, i'd look to Compressor.


nick


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 11, 2017 at 2:19:51 am

Thanks Nick. When you say rip it at its original frame rate, do you mean the 23.976 rate or the original 24 film rate?


Return to posts index


Dave LaRonde
Re: Frame Rate When Ripping DVDs?
on Feb 11, 2017 at 4:00:25 am

The file's at 23.976. Keep it that way. You're asking for trouble if you change it.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 11, 2017 at 4:42:47 am

Thanks for your help everyone!


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 11, 2017 at 4:54:39 am

Just a couple other questions. If the NTSC decided to lower the bandwidth to allow for color video, why didn't they decrease the bandwidth used for audio so that video could still be at 30fps?

And when slowing down film from 24fps to 23.976 and video from 30fps to 29.97, does that change the pitch of the audio at all, or is the pitch the same and just the length different?


Return to posts index


Nick Meyers
Re: Frame Rate When Ripping DVDs?
on Feb 12, 2017 at 9:31:15 pm

"why didn't they decrease the bandwidth used for audio so that video could still be at 30fps?"

dunno!

"does that change the pitch of the audio at al"

yes, but not by much.
I think that for many years this was simply tolerated,
but now with better tools, it may be dealt with.

why not check for yourself?
Conform a clip with audio you are familiar with (including music) thru CinemaTools.
have a listen.


but why I'm back is i just read this about Resolve 12.5:

"23.98 and 24fps material can be rendered to 29.97 and 30fps: It seems like most projects deliver in 23.98, but just this month I had a job that required delivery to 29.97. Having this render option available saves a conform step and is indispensable when delivering directly from Resolve."



nick


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 12:12:13 am

Thanks Nick. If I rip a DVD using mpeg streamclip and the movie is 23.976, does that mean it's progressive? Or is it really interlaced and I should check "deinterlace video" if I'm working in a progressive timeline?

And when would someone use "interlaced scaling"?


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 4:28:13 am

Also, I've been reading different articles about this subject and now I'm not so sure what's going on. I looked at the frame rates of several of my my movie DVDs (originally 24fps movies) in MPEG Streamclip and it said all of them were 23.976 fps. But I also read some articles that said movies put on DVD aren't actually 23.976 fps but are really interlaced into separate fields. And that all NTSC DVDs are 480i and are displayed at 29.97 fps.

Now, when MPEG Streamclip is telling me the movies are 23.976, does this mean it's just telling me the frame of the video file before it was actually put on the DVD? Is it really 29.97fps (or 59.94 fields per second) and the 23.976 is just info about the video before put on a DVD? Or is the actual movie file 23.976 on the DVD and the DVD has flags that tell a DVD player to split the film into fields, which would be 47.952 fields per second (23.976 x 2), and then it also has flags to tell the player to do 2-3 pulldown?

I'm not sure, but I think what's happening is that during the telecine process, the 24fps movie is slowed down to 23.976fps, and then it's split up into fields, achieving 47.952 fields per second, and this video file is what's put on the DVD. And the DVD has flags telling the player to do 2:3 pulldown. So this would mean non-progressive DVD players are 60hz, right?

When I play a DVD on my Blu-ray player, it says 1080/60p, 48 khz. So, this tells me that the player is upscaling the 480i content to 1080, using 2-3 pulldown to convert the 23.976fps to 29.97 fps (59.94 interlaced fields), and then combining each of those fields into single frames, and having each one on the screen twice so that it's now 60 fps. But then the 48hz thing throws me off. I thought 48hz means it's just refreshing the screen 48 times per second, twice the rate of 24 fps. When I click through a movie frame by frame, it takes 24 clicks to go one second. So why does it say 60p if each second is actually 24 frames? Is it doing pulldown, and then reversing it or something? What does it mean if my player is 60hz and the Blu-ray player is 48hz?


Return to posts index


Dave LaRonde
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 5:24:12 am
Last Edited By Dave LaRonde on Feb 13, 2017 at 5:54:52 am

[Bobby Hall] "I also read some articles that said movies put on DVD aren't actually 23.976 fps but are really interlaced into separate fields. And that all NTSC DVDs are 480i and are displayed at 29.97 fps."

Incorrect. DVDs can indeed be 23.976. The DVD player can add the 3:2 pulldown to play back at 29.97.

[Bobby Hall] "But then the 48hz thing throws me off. I thought 48hz means it's just refreshing the screen 48 times per second, twice the rate of 24 fps."

Sorry, but incorrect again. it's NOT 48hz, it's 48kHz. It's the audio sample rate. It has nothing to do with the frame rate.
A Blu-Ray player playing an SD DVD 1080p60 plays back the 23.976 file in the following fashion: First, it blows up the 720x480 image to 1920x1080. Second, displays a frame 3 times, then the next frame 2 times, then 3, then 2, 3, 2, 3, 2... does the pattern sound familiar? It's 3:2 pulldown... only done at 59.94 fps. If you do the arithmetic using the easier numbers 24 and 60, you'll see that one second's worth of 24 frames played back 3-2-3-2-etc. on a Blu-Ray will work out to one second's worth of 60 frames.

[Bobby Hall] "Or is the actual movie file 23.976 on the DVD and the DVD has flags that tell a DVD player to split the film into fields, which would be 47.952 fields per second (23.976 x 2), and then it also has flags to tell the player to do 2-3 pulldown?"

No, no, no, no! Look at how a Blu-Ray does 3:2 above. For 4 frames of a 23.976 file, a DVD player displays 3 FIELDS, then 2 FIELDS, then 3 fields, then 2 fields. 3:2 pulldown. Again, if you do the arithmetic using the easier numbers 24 and 60 (fields), you'll see that one second's worth of 24 frames played back 3-2-3-2-etc. on a DVD will work out to one second's worth of 60 fields

I'm not a fan of the frame rates 23.976, 29.97 and 59.94 either. It would be a lot tidier if it was 24, 30 and 60. But it's not. And as mentioned previously, frame rates are a measure of time. So you can have fractional frame rates -- they're measures of time. That's life in NTSC-Land. It's been that way for 64 years. You'll just have to get used to it.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Nick Meyers
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 5:34:12 am

Standard def TV was always interlaced.
the fields were not counted back then, just the frames.

the file on the DVD is 23.976 (why waste data-rate with duplicated fields?)
it displays on a TV as 29.97 ( i belevie the player does this)

(( im no expert as i live in PAL land, as I've mentioned. i would imagine - or hope- that modern TVs don't need to have redundant fields added to bulk the frame rate up to 29.947, achieving nothing but a weird motion in the process. i would hope that a modern monitor could display 23.976, but what do i know? ))


the 48Khz you see is referring to the Audio.


nick


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 6:13:28 am

Thanks Dave and Nick!

I thought DVDs were interlaced (480i) and don't store progressive files. Is this not true? Is there really a 24p file on the DVD (I'm using whole numbers for the sake of simplicity) or is it really 48 interlaced fields with flags to do 2-3 pull down? If there really is a progressive file on there, why aren't DVDs called 480p instead of 480i?

And when I'm ripping DVDs in MPEG Streamclip, should I uncheck "interlaced scaling"? And what about the "deinterlace" option?


Return to posts index

Nick Meyers
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 8:56:30 am

they are interlaced

"should I uncheck "interlaced scaling"?"
i dont know , what does the manual say

no don't de-interlace. you need the fields for the pulldown to work.

basically rip from the DVD as clean as possible, do everything else afterwards.
that's what i would do.


Return to posts index

Dave LaRonde
Re: Frame Rate When Ripping DVDs?
on Feb 13, 2017 at 3:30:00 pm

[Bobby Hall] "I thought DVDs were interlaced (480i) and don't store progressive files. Is this not true?"

Yes and no. For progressive files, it displays two fields from the same frame. It's called, "progressive segmented frame". So it's a progressive frame displayed as 2 fields.


[Bobby Hall] "Is there really a 24p file on the DVD (I'm using whole numbers for the sake of simplicity) or is it really 48 interlaced fields with flags to do 2-3 pull down?"

This has been explained above. Read the 3-field, 2-field, 3-field, 2-field stuff again. I see you didn't put pencil to paper to figure out how this stuff really works, but are trying to dope it out from incorrect assumptions.


[Bobby Hall] "And when I'm ripping DVDs in MPEG Streamclip, should I uncheck "interlaced scaling"? And what about the "deinterlace" option?"

I've used that software ONCE. With the defaults. The result was fine...
well, as fine as SD MPEG2 video at a max bit rate of 6 MB/sec could be.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 14, 2017 at 1:08:55 am

Dave, when I asked if a 24fps film on a DVD is really 24 frames or 48 interlaced fields, I was using the term "interlaced" to mean progressive segmented frames (never heard that term till you used it). I understand that the two fields of a progressive frame represent the same instance in time. So what I meant to ask was, is the file on the DVD 24fps, or is it actually 48 segmented frames per second? If the file is 24 fps, then wouldn't that mean the DVD has flags that tell the player to split up those frames into segmented frames (two fields per frame representing no change in time), and then displaying those 48 segmented frames using 2-3 pulldown?

Also, if I have a DVD of a tv show that was shot with video, this means it was shot 60 fields per second, right? And when put on a DVD, it combines those fields into 30 fps. So in this case, the two fields of a frame are different instances of time. So wouldn't this make each frame blurrier than a 24p frame? If you pause a 24p file, you're seeing an entire frame of a still moment in time. And when you pause a 30i frame, you're seeing two interlaced fields recorded 1/60 of a second apart, right?


Return to posts index

Dave LaRonde
Re: Frame Rate When Ripping DVDs?
on Feb 14, 2017 at 3:45:22 pm

[Bobby Hall] "is the file on the DVD 24fps, or is it actually 48 segmented frames per second?"

Whenever I've dealt with 23.976 SD progressive video -- and I'll grant you, it's been a while -- I've thought, "It's a frame." I NEVER, EVER had any problems.



[Bobby Hall] "If you pause a 24p file, you're seeing an entire frame of a still moment in time. And when you pause a 30i frame, you're seeing two interlaced fields recorded 1/60 of a second apart, right?"

That is correct. There's an FCP setting that displays both fields of a frame. In clips with a lot of motion, you'll see the interlacing in footage shot interlaced scan, but NO interlacing in footage shot progressive scan.

[Bobby Hall] "If the file is 24 fps, then wouldn't that mean the DVD has flags that tell the player to split up those frames into segmented frames (two fields per frame representing no change in time), and then displaying those 48 segmented frames using 2-3 pulldown?"

Nope. No flags necessary. The file headers on clips contain the frame rate, and DVD players know how to handle them. Actually, it's the DVD authoring software that inserts code on DVDs that program DVD players to take care of business.

[Bobby Hall] "So wouldn't this make each frame [60i] blurrier than a 24p frame?"

Actually, it's the reverse. There would be more motion blur in a progressive frame than in an interlaced frame. The imaging sensor is exposed for a longer time in progressive scan than in interlaced scan. There's a greater chance of motion blur in a longer exposure.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 14, 2017 at 11:42:55 pm

Thanks for all the info. I was curious, why are DVDs encoded with the 29.97 frame rate instead of the field rate? If digital video is recorded at 59.94 fields per second and also shown on analog TVs at 59.94 fields per second, what's the point in taking an extra step and encoding them to a frame rate if they're just going to be displayed as a field rate later on? When movies first started to be edited digitally, was there some type of requirement that 24 fps movies had to be converted to 29.97 for editing?


Return to posts index

Dave LaRonde
Re: Frame Rate When Ripping DVDs?
on Feb 15, 2017 at 4:14:55 pm

[Bobby Hall] "why are DVDs encoded with the 29.97 frame rate instead of the field rate?"

Simple -- 2 fields make one frame. Now mind you, this doesn't apply to 24p DVDs... other than that Progressive Segmented Frame deal discussed earlier.



[Bobby Hall] "When movies first started to be edited digitally, was there some type of requirement that 24 fps movies had to be converted to 29.97 for editing?"

Ah, the days of the EditDroid. Go look it up. They cut at 24fps. Then they conformed their edits to the actual 24fps film for projection.

Ever see a movie on TV, say between 1953 and 1998? They used 24 fps film projected at 23.976 fps, and the broadcast facility's film chain added the pulldown to get it to 29.97. The actual video sensing hardware evolved over that period from pickup tubes to flying spot scanners to chips, but the princciple remained the same. They've been doing this stuff for a LONG time.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Bobby Hall
Re: Frame Rate When Ripping DVDs?
on Feb 15, 2017 at 10:38:27 pm

Since progressive TVs show progressive frames and a film movie from a progressive DVD player will be shown at 24fps, that got me wondering about how DVDs are displayed with other types of players and TVs used.

Regarding a 24fps movie DVD:

Will playing that movie on an interlaced DVD player on an analog TV show the movie at 30 fps (60 fields per second)?

How many fps will the movie be displayed at with an interlaced DVD player on a progressive TV? Will the TV remove the repeated fields and display 24 fps?

Obviously using a progressive player and progressive TV will display at 24 fps, but what about a progressive player with an analog (interlaced) display? Will it show 24 fps or use the 2-3 pulldown flags and display at 30 fps? And if it's 30 fps, is it showing complete frames or is it actually 60 segmented frames per second (showing the odd lines of one frame for 1/60 of a second and then the even lines of the same frame for 1/60 of a second)?


Return to posts index

Michael Gissing
Re: Frame Rate When Ripping DVDs?
on Mar 10, 2017 at 4:28:29 am

The speed difference is .1%, far too small to have any pitch consequences.

My understanding of the need to shift frame rates from 30 to 29.97 was that the color subcarrier was being modulated by the line frequency of 60hz causing a moire pattern on B&W TVs. Rather than solve this issue, NTSC just changed the frame rate of color broadcasting, thereby creating a nightmare for everyone who came after them.

Sometimes an engineers elegant solution has longer term tragic consequences, much like the decision to have two toally different shaped CO2 filters on the Apollo mission.


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]