Quantcast Super 8mm Transfer to Digital - digitalFAQ Forum
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10-26-2011, 11:30 PM
JasonCA JasonCA is offline
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Hi Everyone,

I am a bit confused.

I had some Super 8mm film transferred to digital by a professional transfer service.

Though the actual film is at 18fps, the digital video stream is 23.976fps.

When playing the digital video stream at it's normal 23.976fps speed, the video itself looks fast. Because of this, I think the video needs to be slowed down to 18fps.

And, I don't want to loose any frames goings from 23.976fps to 18fps. However, I am not really sure what I need to do?

From what I have read, I need a 2:3 Pull down which is know as a reverse telecine. In other words, I want to remove the filler frames and just have the authentic real frames as if viewed right off the Super 8 film itself. I'm not sure how to do this? And, do I really need to do a 2:3 Pull down? How do I know? Or how can I tell?

However, if the film was scanned at 23.976fps, then I am sort of believing then there are NO filler frames. Meaning, there are no extra frames in the video stream that are FAKE and don't belong? If so, then I guess it's simply a matter of SLOWING the 23.976fps to 18fps.

If the Super 8mm film was scanned at 23.976fps, then really there is no data that changes. I believe then it's really only a matter of making the video play back at 18fps? I'm a bit confused.

Maybe someone here knows better what I may be looking for? Or perhaps, someone can help to clear my understanding of this process.

Thanks in advance!

Jason
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  #2  
10-26-2011, 11:51 PM
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Quote:
Originally Posted by JasonCA View Post
Hi Everyone,
Hell, welcome to the site.

Quote:
I am a bit confused.
Based what I'm reading, you're not the confused one. Let me explain...

Quote:
I had some Super 8mm film transferred to digital by a professional transfer service.
Though the actual film is at 18fps, the digital video stream is 23.976fps.
When playing the digital video stream at it's normal 23.976fps speed, the video itself looks fast. Because of this, I think the video needs to be slowed down to 18fps.
Based on this description, the "professional service" you used is amateur. The person who butchered your video is the confused one. They've screwed up, and now you'll have to fix it. Luckily, this isn't a difficult task, assuming they've also not introduced an interlacing layer to the equation (which I'm afraid may be the case).

Quote:
And, I don't want to loose any frames goings from 23.976fps to 18fps. However, I am not really sure what I need to do?
From what I have read, I need a 2:3 Pull down which is know as a reverse telecine. In other words, I want to remove the filler frames and just have the authentic real frames as if viewed right off the Super 8 film itself. I'm not sure how to do this? And, do I really need to do a 2:3 Pull down? How do I know? Or how can I tell?
However, if the film was scanned at 23.976fps, then I am sort of believing then there are NO filler frames. Meaning, there are no extra frames in the video stream that are FAKE and don't belong? If so, then I guess it's simply a matter of SLOWING the 23.976fps to 18fps.
If the Super 8mm film was scanned at 23.976fps, then really there is no data that changes. I believe then it's really only a matter of making the video play back at 18fps? I'm a bit confused.
18fps (actually 17.982 frames per second) should have pulldown at 4:3:3, to reach NTSC 29.97fps.
One-third of your Super 8 source frames needed to be duplicated. This would give 24fps.
From there, it would have been telecined into 29.97fps video, in order to created a compliant DVD-Video.

Whoever did your video skipped the conversion from 18fps (480p18) to 24fps (480p24)

You're now faced with this workflow:
- Inverse telecine (IVTC) the DVD back to 24fps video, if needed.
- Slow down 24fps to 18fps.
- Do a proper 18fps to 24fps conversion, inserting duped frames.
- Do a proper 24fps to 29.97i DVD-Video telecine encode, and author a new disc

You'll want to use Avisynth.
There's a good thread on Doom9, documenting some of this: http://forum.doom9.org/showthread.php?t=69876
HOWEVER, there's a mix of good and bad information there. You'll need some guidance on what's right for your exact situation.

It's very likely this could be done in one pass, with a proper Avisynth script.
I'd want to see a sample clip of the video you have to work with, in order to know proper settings.

Quote:
Maybe someone here knows better what I may be looking for? Or perhaps, someone can help to clear my understanding of this process. Thanks in advance! Jason
Have I helped clear some of it up?

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  #3  
10-27-2011, 02:31 AM
JasonCA JasonCA is offline
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Quote:
Originally Posted by lordsmurf View Post
Hell, welcome to the site.

Based what I'm reading, you're not the confused one. Let me explain...

Based on this description, the "professional service" you used is amateur. The person who butchered your video is the confused one. They've screwed up, and now you'll have to fix it. Luckily, this isn't a difficult task, assuming they've also not introduced an interlacing layer to the equation (which I'm afraid may be the case).
Hello there lordsmurf!

They may have butchered it, or I may have not explained it well. So, I will share a few things I may have missed in hopes that it helps:

My original Super 8mm film is filmed at 18fps; these are home movies. And, I had the Super 8mm film scanned at 1080p with a scan rate of 23.976fps. Obviously, 8mm films are not as wide by today's standards. So, the film is pillerboxed in the 1080p resolution.

Now, when I received the video as a file which is uncompreesed, it's reported fps by software is indeed 23.976fps.

Anyway...on to what you said...

Quote:
Originally Posted by lordsmurf View Post
18fps (actually 17.982 frames per second) should have pulldown at 4:3:3, to reach NTSC 29.97fps.
One-third of your Super 8 source frames needed to be duplicated. This would give 24fps.
From there, it would have been telecined into 29.97fps video, in order to created a compliant DVD-Video.
This is where I get lost.
1) How did you arrive at 17.982frames per second? The Super 8 film is, at least I thought, trully 18 whole frames per second? Or maybe I am wrong.
2) Why does the film need to be pulled down to reach NTSC 29.97fps? Where does 29.97fps come from? The video I received was in an uncompressed format at 23.976fps. I apologize, I didn't make this clear.

Quote:
Originally Posted by lordsmurf View Post
Whoever did your video skipped the conversion from 18fps (480p18) to 24fps (480p24)
The Super 8mm film originally at 18fps, was scanned at a rate of 23.976fps at 1080p. Again, my apologies, I may not have made that clear early on.

Quote:
Originally Posted by lordsmurf View Post
You're now faced with this workflow:
- Inverse telecine (IVTC) the DVD back to 24fps video, if needed.
- Slow down 24fps to 18fps.
- Do a proper 18fps to 24fps conversion, inserting duped frames.
- Do a proper 24fps to 29.97i DVD-Video telecine encode, and author a new disc
I never received the video on DVD. I requested a uncompressed video file. And so the video file is 24fps. So this being the case:

Questions & Thoughts:
1) I am assuming their may be duped frames to get the original 18fps to 24fps?
2) Or, perhaps there are NO dupped frames since it was scanned at 24fps where I may ONLY need to slow down the video to 18fps? My question is how do I get the 24fps (23.976fps) video BACK to it's original 18fps; is a reverse 2:3 pulldown needed (reverse telecine)? I may be confusing things considering it was scanned at 23.976fps. If it was scanned at 23.976fps, then perhaps it just needs to be slowed down to 18fps? Maybe that's all I need to do, but I am afraid of loosing frames.

As I said earlier, when playing the scanned video file at 23.976fps (which it by default what it plays at), the video looks fast. So this means, at least to me, that the video should be slowed down to 18fps to be at its natural frame rate. However, I am wondering if I slow it down to 18fps if I loose frames?

If the video was scanned at 23.976fps, then this means that there are actually 23.976 whole frames per second WITHOUT duped frames?

Are there any software tools that say this so and so file is 23.976fps at a pulldown of 4:3:3? Or is there any tools that show how the frames are interleaved? How do I know that there are 23.976 whole frames at 23.976fps? People talk about AA bb Ab Ba, but are there any software tools that reflect how frames are laid out?

Quote:
Originally Posted by lordsmurf View Post
You'll want to use Avisynth.
There's a good thread on Doom9, documenting some of this: http://forum.doom9.org/showthread.php?t=69876
HOWEVER, there's a mix of good and bad information there. You'll need some guidance on what's right for your exact situation.

It's very likely this could be done in one pass, with a proper Avisynth script.
I'd want to see a sample clip of the video you have to work with, in order to know proper settings.

Have I helped clear some of it up?
Yes, you have been quite helpful! Though I fear I may have mislead you. So I look forward to hearing your thoughts on what I just recently shared.

Though I have read through the other forum with the link you provide, I will study that a bit more as well.

On another similar but separate topic somewhat, I had the video scanned at 444 RGB 10-bit uncompressed. So it makes me wonder how I prove that the data I received is really 444RGB and say not 422 RGB? For all I know at this point, it could have been scanned at 422 RGB even though I requested it to be scanned at 444 RGB. It's these things I need to prove to myself so I know things are correct. My guess is that I somehow need to take the size of the file and do some calculations to prove that the video data consists of 444 data instead of 422?

Look forward to your thoughts!

Thanks again for your response!

Jason
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  #4  
10-27-2011, 03:42 AM
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17.982fps is actual speed calculated after telecined to 29.97fps (or 23.976), and then reversed. You must display all SD NTSC video at 29.97fps -- nothing else is valid. 24fps is telecined to 29.97, becoming 23.976 in the process. "Progressive scan" DVD players and HDTVs undo the telecine on-the-fly (IVTC) to display progressive again.

Being an HD capture does change this a bit, as BDMV supports "true" 24fps in 720p and 1080p. (i.e., 1080p24 and 720p24)

Before you get too worked up about 4:4:4 vs 4:2:2, at these higher-than source resolutions, it probably won't matter too much. Super 8 is not even a 1K theoretical resolution, which is well below 1080p, and closer to 720p. Beyond that, most 8mm films ("Super" or not) are limited in detail due to the optics of the camera. So many people focus on the medium, overlooking the lenses in use. The latitude (color depth) of Super 8 also varies, and is subject to aging even after development. So you're probably going to be spending time color-correcting in an editor, regardless of colorspace or film stock used. In theory, yes, 4:4:4 would be better, but assuming any standardized output will be used, 4:2:2 will be more than adequate. If nothing else, it's going to save some file space (and RAM/CPU time, as well as disk swap, making your project easier to work with in an editor). Do the math to figure it out, yes.

If the 18fps was 1:1 to 24fps, then you'll need to alter the file to display at 18fps, and then do the frame duping to achieve the 24fps. Aside from computer viewing, no format supports 18fps. Slowing 24 to 18 will not drop frames unless you're using the wrong method. The Avisynth methods being discussed are the proper solutions here. However, there are limits to Avisynth, so I'm not sure which colorspaces and resolutions are supported. You may have to use Premiere Pro or Final Cut Pro to do some of this.

There's no software that can interpret film like you're asking. That would require AI. You'll need to view the film frame by frame, to see if there are any dupes.

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  #5  
10-27-2011, 09:52 PM
JasonCA JasonCA is offline
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Quote:
Originally Posted by kpmedia View Post
If the 18fps was 1:1 to 24fps, then you'll need to alter the file to display at 18fps, and then do the frame duping to achieve the 24fps. Aside from computer viewing, no format supports 18fps. Slowing 24 to 18 will not drop frames unless you're using the wrong method. The Avisynth methods being discussed are the proper solutions here. However, there are limits to Avisynth, so I'm not sure which colorspaces and resolutions are supported. You may have to use Premiere Pro or Final Cut Pro to do some of this.
The problem is I am still not sure if there are duped frames are not? Right now at 24fps, as I told lordsmurf, the video appears fast. Therefore, I think the 24fps digital video needs to be slowed down to 18 fps for it to look normal (like it does on Super 8 film at 18fps).

My argument (or really point since I am discussing and not truly arguing) is this: If the digitized super 8 video 'looks' like the right speed at 24fps, then I would feel more inclined to believe there are duped frames added to pad the video to look right at 24fps. Because, the reality is, the digitized super 8 video should 'look' normal when it's played at 18fps and not normal when played at 24fps. This is not the case.

Instead, the digitized super 8 video truly looks FAST at 24fps. Because of this, I don't see how there could be duped frames? Is my understanding correct here? So to me, the digitized super 8 video looks like it needs to be slowed down to 18fps. I think this is the case, but it's why I am asking? I could very well be wrong. If I slowed it down to 18fps, it would look like the true super 8 frames per second of the film.

I guess I am uncertain how to best verify that the digitized frames look identical to the Super 8 frames? I guess the only true way to do this would be to step through the actual Super 8 film, one frame at a time, and compare it to each digital frame? Is this one way to do it?

How does one detect duped frames? Is a duped frame only when the entire image doesn't change? Is that the best technique to determine if the frame changes?

I suppose this assumes there is no type of flame blending when the 8mm super 8 film was digitized to a video file.

Anyway, I look forward to what lordsmurf has to say to my prior prior response too.

Thanks for the feedback!

Jason
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  #6  
10-27-2011, 10:58 PM
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You're understanding it backwards.
18fps @ 24fps = too fast
18fps + dupe frames @ 24fps = proper speed (does not appear "fast")

More frames makes it slower. That's why frames have to be duped.

If it's too fast, you can't have dupe frames. (Or if it does have duped frames, the video is massively screwed up, but this is unlikely.)

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