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Old 15th April 2013, 20:09   #1  |  Link
zilog jones
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Decimate to target framerate (source not blended/interlaced)

I have some captures of games made with DOSBox.

When DOSBox is capturing, it will create the video with framerate of the current video mode it's emulating, which can be anything from 35-70 fps. Every time the video mode changes, it starts a new AVI.

However, a lot of old DOS games do not run anywhere near these speeds, and many 3D games are really doing more like 15-20 fps, resulting in a video with many duplicate frames but totally inconsistent frame patterns.

I'd like to try and convert them to 30 fps for editing, and eventually maybe YouTube. Since the real framerate is quite low I think this should be achievable without blending frames.

I've got good results with just srestore(30), but it's quite slow and I don't have any blended frames to deal with so maybe there's some faster alternative? Or is there some way to make srestore not look for blended frames?
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Old 16th April 2013, 10:54   #2  |  Link
ajk
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How about just ChangeFPS(30) ?
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Old 24th April 2013, 01:46   #3  |  Link
osgZach
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Would probably just end up with one jerky clip..

Video Capturing on the PC is iffy when it comes to games, but it sounds like you need to use something a little better than a native dosbox capture.. (I use Dxtory) Or you need to be doing this on a more powerful PC.. I don't remember having multiple video files when I recorded some Stargunner footage back when I played with that for a bit.

Or perhaps find out if there are some settings you can change to get a more consistent video from Dosbox.

Last edited by osgZach; 24th April 2013 at 01:49.
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Old 24th April 2013, 02:54   #4  |  Link
poisondeathray
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Maybe TDecimate:

TDecimate(mode=2, rate=30) , or try TDecimate(mode=7, rate=30)
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Old 24th April 2013, 23:02   #5  |  Link
osgZach
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Expounding a little further, since I re-read the question.

I suppose if I were to try this I would do the following steps.

Identify all your arbitrary framerates and decimate them by hand if necesarry, or if there is any kind of sensible pattern, go with that and run it through a decimation filter with the pattern you want.
Save your new files out named in some way to identify their FPS, keep a master sheet, whatever you wanna do.

Find a way to splice them all together, and encode your final movie file; we're keeping track of all the spliced frame ranges here also so we know what timecodes to use on which range of frames. You'll probably have to decide a base framerate (I'd go with the most common framerate you come across, hopefully 30 or 60) for that pesky "AssumeFPS" we have to throw at the top of the timecodes. Any ranges matching your base you won't need to define. But anything deviating you should.

Throw it into an MKV with the timecodes file and pray?

I'm guessing this could be done, perhaps even easier than I make it out to be, but I'm loathe to try it myself. It probably comes down to a middle-ground how accurate you want your decimation to be and how much time you want to spend on it.

The whole idea kind of piques my interest though, so if you care to throw up 2 or 3 different FPS captures (in a sane file size) that are otherwise unmodified, I'd be interested in playing around with them. I know you mentioned video mode changes, so I suspect there may be some scaling to do as well.

Last edited by osgZach; 24th April 2013 at 23:10.
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Old 26th April 2013, 06:16   #6  |  Link
ajk
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If the original material is essentially variable framerate at 15-20fps (depending on complexity of 3D scene), and the target is YouTube, ie. constant 30fps, anything beyond ChangeFPS(30) sounds too elaborate to me
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Old 26th April 2013, 13:46   #7  |  Link
osgZach
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That's true. They'll just re-encode it to 30fps.
Youtube is terrible for game footage anyway.
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