DVD intervals for screen capture
October 27, 2004 9:27 AM   Subscribe

We are in need of an application which will allow us to advance a Digital Video Disk to specific intervals (0:00:00) for the purpose of screen capture.

( Macintosh Operating System, Ten point Three point Five ) This delight possibly and preferably would be Free or for Sharing, though we have nefarious means at our disposal should there be a Fee for such Fun.

( VideoLAN Client does not appear to offer such a feature, of course we very well could be guilty of oversight. )

This application would be put to use gathering intertitles from a selected set of films dated between 1914 and 1926 in order to digitize the typefaces. While we don't mind watching the pictures and noting the times of intertitle occurrences, we do mind sitting in front of a computer terminal in agony whilst attempting to 'scrub' blindly to the proper places.

Yes, yes. That is all.
posted by tenseone to Computers & Internet (14 answers total)
DVD Player within MacOS X will do this, using an Applescript which is included with the player.

Look in the scripts menu when DVD Player is launched.
posted by tomierna at 10:00 AM on October 27, 2004

Apple-Shift-Zero isn't doing it for you? It's a built in AppleScript in the Scripts menu in DVD Player in 10.3.5.
posted by bcwinters at 10:04 AM on October 27, 2004

Oops, didn't see that previous response when I previewed. At least now you have the keyboard shortcut, too ;)
posted by bcwinters at 10:07 AM on October 27, 2004

Yes, thank you. Though Digital Video Disk Player disables all screen capture devices—as far as I know—unless there is way around this tragedy.
posted by tenseone at 10:13 AM on October 27, 2004

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posted by tenseone at 10:14 AM on October 27, 2004

I use mplayer to do screen grabs. You can specify where you want the grabbing to start and end, how many frames you want, etc. It's a command-line based program. Not 100% sure of it's availability for OSX because I don't do OSX but since it's available for most unices and windows I think there probably is an OSX version, or it'll compile under OSX.

If you're interested I could post an example of how one might use mplayer to do this. I use it to extract, say, 10 frames from a movie clip so that I can tell what's in it without watching.
posted by RustyBrooks at 12:23 PM on October 27, 2004

Oh, thank you, Mr Brooks! We do have mplayer installed, though we have never used it for more than viewing a troublesome .avi or some other such nonsense.

Any examples you would be willing to share would be most, most appreciated.

If we can establish a technique for finding positions within a DVD without the arduous task of locating the bits by hand, though still being able to gather screen captures, we shall be forever indebted.
posted by tenseone at 12:52 PM on October 27, 2004

extract, say, 10 frames

It just occurred to us (surprisingly) that this seems perfect, as we only need one frame at a time (an instance of an intertitle) from about twenty positions on the disk.
posted by tenseone at 1:01 PM on October 27, 2004

mplayer -osdlevel 0 -nosound -frames 10 -sstep 120 -vo jpeg myfile.avi -jpeg outdir=/path/to/output

This example would take one sample every 120 seconds, for a total of 10 frames, from myfile.avi, output to /path/to/output.

To do this from a dvd, I believe you use a file name like dvd://2 which, in this case, would be the second title on the dvd. I haven't really tried this with a dvd lately so I don't remember exactly.

Good luck, let us know how it goes.
posted by RustyBrooks at 1:20 PM on October 27, 2004

It occurs to me that this might not be *exactly* what you need. For example it's going to start at frame 0 and go every 120 seconds in this case. There might be a way to start at a particular spot, I'll browse around and take a look. If not, say you wanted the frame at 40:17 (2417 seconds into the movie):

mplayer -osdlevel 0 -nosound -frames 2 -sstep 2417 -vo jpeg dvd://2 -jpeg outdir=/tmp

This would give you the first frame and the frame at 40:17, you could discard the first one. There is probably a more elegant way to do it than that.
posted by RustyBrooks at 1:24 PM on October 27, 2004

ah, the -ss option. So -ss 40:17:00 seeks to, well, 40:17:00 and starts from there.

Mplayer is the exact thing to use for all your video needs, imho. I watch movies on it (it plays EVERYTHING fairly well), encode and re-encode things with it (it can re-encode anything it can play and usually does a good job. It's terrific at 2-pass encoding of DVD's to AVI for example, or converting anything to an avi). As mentioned here it's good at grabbing frames. I use it to identify the codec, etc in random movie files. Although there are probably some graphical interfaces for it out there, I tend to write little scripts that do this and that, which is to some's taste, and not to others.
posted by RustyBrooks at 1:29 PM on October 27, 2004

Apparently, the MPlayer unsupported binary for MacOS X is a ridiculously pared-down and low-rent version of the cli tool.

Though while it refuses to open DVDs, it appears that it may, just may, open a TS_VIDEO folder. Fortunately, all the material we are working with is unencrypted, unfortunately it will take a few hours to copy the TS_VIDEO folders from six-or-so DVDs. (We are half to three-fourths tempted to simply convert these DVDs to .avis and skip all the fuss.)

This is no doubt the proper direction: as we can see that this pseudo-MPlayer will allow seeking, once we feed it a format it enjoys.

We do wish we were more knowledgeable about these sorts of things so we could install MPlayer from source. It seems that fink has every component of the 'real' MPlayer available, save the actual application itself.

Thank you again, Mr Brooks, we do believe that we are certainly on the right track!
posted by tenseone at 3:21 PM on October 27, 2004

any reason you can't mount the dvd's in a dvd-rom drive and read the ts_video folder from there?

Not being in front of your computer it's not easy to tell why it is that it won't read it for you. There are lots of options for mplayer to tell it what dvd://1 refers to (the device and what not) but I've got 0 experience with macs.

Compiling from source may not be too bad if you're lucky. At least give it a shot. Download the source, unpack it, cd into that directory, and do a
and if that doesn't fail try a
and if that doesn't fail, make install and you're home free.

If it does fail, well, I can't help you too much there ;)
posted by RustyBrooks at 8:51 PM on October 27, 2004

Oh my, thank you ever so much!!

While we were not able to install all the proper libraries to accomplish a direct frame to jpeg (ignorance and frustration), we are able to advance the DVD to an exact frame and pause. This is more than perfect as-is, for we can simply take a screen capture at that point in time.

Thank you again, we are so pleased that we brought this conundrum to AskMetafilter and that you were willing to go out of your way to help. MPlayer is certainly our new found friend.
posted by tenseone at 9:09 AM on October 28, 2004

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