Feature idea: slate info metadata file

[Tramm Hudson]

I had an idea for a new feature in Magic Lantern: a slate meta-data record in the EXIF or in a separate file. I'm already thinking about recording the lens data into a time-synced file, so it would be fairly easy to also have a menu that allows selecting "Scene", "Shot", "Take", etc, with an auto-incrementing take counter after each clip is recorded.

Another additional feature would be the ability to add a rating to the clip after recording and review so that good takes are easier to find while importing a card full of scenes.

The question is how would this sort of meta-data interface with FCP or other tools? Is there a standard format for logging these data?

[Zeke Kamm]

Hi Tramm,

Wish I could answer your question, but instead would just like to say that I would LOVE to have this feature. Very handy.

Maybe this is a bit lower tech than you were thinking, but even if it just put out a txt or Excel file that listed the scene / shot / take and a quality rating along with the file name, that would work fine for me. I could just refer to that list when I sit down to edit.

[Bob Thompson]

Hi Tramm

Try downloading a free copy of Microsoft expression media and see if you could implement any features that could enhance their catalogs.

The software works very well, you only need to drop a clip on the app and it grabs the 1st frame of the video and a lot of the "exiff data"

bob

[Tramm Hudson]

Originally Posted by Bob Thompson

[...] you only need to drop a clip on the app and it grabs the 1st frame of the video and a lot of the "exiff data"

The .THM file created along with the movie is a normal jpeg, just renamed. It has all of the normal EXIF fields, although I don't think some of them can be trusted. For instance, the exposure and fnumber are "Infinite", while the iso and shutter are 0. The date appears to be correct.

I don't see any easy way to change the EXIF fields that are written, so I was thinking of a text file that had timestamps, shutter, iso, aperture, lens info and the scene/shot/take and rating info. This way the new parameters can be written as they are changed while recording.

I've created two issues for it: Slates and Lens meta-data recording

[Jim Froom]

Because there are so many editing programs, I think keeping it simple is best.
A txt file with the information in it would probably be a good first step. Then maybe some other programmers could take and do something more with it for the different usages.

I'm pretty confident that there are so many different work flows, that it would a fulltime job for a year to make something work universally, and I'm not even sure that's possible.

The CSV file format would be cool. That way you could have your headers (ie field names) and then the data underneath which would allow people to use the data in other automated fashions in the future.

[Peer Landa]

Originally Posted by Tramm Hudson

I had an idea for a new feature in Magic Lantern: a slate meta-data record in the EXIF or in a separate file. I'm already thinking about recording the lens data into a time-synced file, so it would be fairly easy to also have a menu that allows selecting "Scene", "Shot", "Take", etc, with an auto-incrementing take counter after each clip is recorded.

If you can do that, can you also do SMPTE time-code... maybe possibly perhaps...?

If so, I'll put your picture up on my wall -- my new hero.

-- peer

[Jay Bloomfield]

Originally Posted by Tramm Hudson

Is there a standard format for logging these data?

There is no standard format for passive metadata across OSes, video wrappers and NLEs. Adobe CS4 uses XMP:

XMP metadata in Creative Suite 4 Production Premium | Adobe Developer Connection

[Jeremy Nicholl]

It would be VERY nice to have a way to embed copyright/rights/ownership data in the same way we can in still images. Dodgy clients will of course try to rip it out as they do with stills, but it would still be good to be able to embed it in the first place.

[Al Bogdan]

Tramm,

With all that lens data available, would it be possible to take the lens focal length and the focus distance and calculate DOF? It would be nice to be able to just glance down or press a button and see what the current DOF is in inches.

[Tramm Hudson]

Originally Posted by Al Bogdan

With all that lens data available, would it be possible to take the lens focal length and the focus distance and calculate DOF? It would be nice to be able to just glance down or press a button and see what the current DOF is in inches.

There are only two problems with that. The first is measurement in inches rather than cm. The second is that there is no floating point support and right now my code doesn't have the ability to do arbitrary integer division to implement a fixed point version of the normal formula:



I've added an enhancement request for later: DOF display

[Mike Demmers]

Lookup table.

Shouldn't need many values.

-Mike

[Zeke Kamm]

Originally Posted by Tramm Hudson

There are only two problems with that. The first is measurement in inches rather than cm. The second is that there is no floating point support and right now my code doesn't have the ability to do arbitrary integer division to implement a fixed point version of the normal formula:



I've added an enhancement request for later: DOF display

You guys make my brain hurt.

[Tramm Hudson]

Originally Posted by Tramm Hudson

[...]right now my code doesn't have the ability to do arbitrary integer division to implement a fixed point version of the normal formula:



I've added an enhancement request for later: DOF display

And I just checked in the new code based on the wikipedia formulas. 0.1.6 will have support for depth of field computations and a dedicated "Focus" menu with displays and controls for things like focus stacking.

We are now linking in an integer math library so that it is possible to do such luxuries as integer division and modulus. Still no floating point, so all of this is being done in fixed-point unsigned integers. There will be 32-bit overflows if you try to use the DOF computations with a 1200 mm lens; a bug report will need to be created if this matters to anyone...

[Tramm Hudson]

Originally Posted by Jim Froom

The CSV file format would be cool. That way you could have your headers (ie field names) and then the data underneath which would allow people to use the data in other automated fashions in the future.

Here a commit that implements logging. It writes to a movie.csv file with the lens meta data and a small header:

Start: 2009/07/31 19:59:23
Lens: EF70-200mm f/4L USM
ISO,Shutter,Aperture,Focal_Len,Focus_Dist
800,30,4.0,70,65535
800,30,4.0,70,388
800,30,4.0,70,306
800,30,4.0,70,233
800,30,4.0,70,174
800,30,4.0,70,158
800,30,4.0,70,146
800,30,4.0,70,146
800,30,4.0,70,146
800,30,4.0,70,158
800,30,4.0,70,233
800,30,4.0,70,65535
800,30,4.0,75,65535
800,30,4.0,98,65535
800,30,4.0,135,65535
800,30,4.0,172,65535
800,30,4.0,200,65535
800,30,4.0,200,65535
800,30,4.0,200,65535
800,30,4.0,154,65535
800,30,4.0,84,65535
800,30,4.0,70,65535
800,30,4.0,70,65535

The frame number computation isn't working yet. Nor are the files correctly named. Focus distance of 0xFFFF == Infinity or beyond.