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iJed · Sep 13, 2003, 07:34 PM

I would like to know what QuickTime compatible codec would be best for playing a high resolution movie at speeds ranging from -100 to 100 times playback rate. Not necessarily that fast but as fast as possible before things screw up. I've written a little Objective-C/Cocoa app to let you select speed by key press. App is available here: http://www.geocities.com/jeddhs/mult...dPlayer101.zip. I want to run this on a G5 1.6 or 1.8GHz.

krove · Sep 13, 2003, 09:20 PM

Apple's new Pixlet codec looks like it fits your need. It was developed by Apple and Pixar.

See the right side-bar:
http://www.apple.com/macosx/panther/

iJed · Sep 13, 2003, 11:29 PM

Originally posted by krove:
Apple's new Pixlet codec looks like it fits your need. It was developed by Apple and Pixar.

See the right side-bar:
http://www.apple.com/macosx/panther/

Maybe it would but I want to run on a final OS/QuickTime version today. I'm not sure how good Pixlet will be at high speed due to its large (assumedly) file size.

qnxde · Sep 14, 2003, 12:26 AM

Anything that doesn't use intra-frame compression should work, I'd try Motion JPEG.

Uncle Skeleton · Sep 14, 2003, 01:00 AM

PhotoJPEG does not decode very fast in my experience. If I were you I would just try a few. Hint: there's a reason corporations like Apple have chosen DV for jobs like this (and since choosing it there have been optimizations for it). I'm hoping Pixlet will be even better (the compression is slightly better, so less disk access), but we'll have to wait and see

iJed · 09:29 AM

Originally posted by Uncle Skeleton:
Hint: there's a reason corporations like Apple have chosen DV for jobs like this (and since choosing it there have been optimizations for it).

Unfortunately DV makes extremely large files. Without an exceedingly fast disk drive DV is more or less useless for my task.

subego · Sep 14, 2003, 11:30 AM

Can you throw in more specifics?

How high-resolution?

Why are you doing this (if there's a reason other than using the script)?

Uncle Skeleton · Sep 14, 2003, 12:11 PM

Originally posted by iJed:
Unfortunately DV makes extremely large files. Without an exceedingly fast disk drive DV is more or less useless for my task.

I thought the G5's hard disks were going to be very fast. Anyway, for seeking backwards, you absolutely can not have inter-frame compression, and besides the mysterious Pixlet, There's not much better compression than DV in that camp. You could try some mpeg-4 codecs (3ivx, divx, Apple mpeg-4) and force a new keyframe at 1/framerate seconds on encoding, but it will take more processor time to decode (probably). Like I said before, try some and see

iJed · Sep 14, 2003, 10:19 PM

Originally posted by subego:

How high-resolution?

I was hoping for about 800*600 but I seriously doubt that this is possible at these extreme frame rates.

Why are you doing this (if there's a reason other than using the script)?

An artist I know just bought a PowerMac G5 and asked me if I could throw him together a small program to playback a movie at different speeds by key press. He has a sort of mat keyboard that you can walk on to change the speed. He already had a similar app for Windows.

iJed · 11:27 PM

Originally posted by Uncle Skeleton:
I thought the G5's hard disks were going to be very fast. Anyway, for seeking backwards, you absolutely can not have inter-frame compression, and besides the mysterious Pixlet, There's not much better compression than DV in that camp. You could try some mpeg-4 codecs (3ivx, divx, Apple mpeg-4) and force a new keyframe at 1/framerate seconds on encoding, but it will take more processor time to decode (probably). Like I said before, try some and see

I don't doubt that the G5 hard disks are lightning fast but they are not fast enough to achieve a 50 times DV data rate. I'm beginning to think that the best way of doing this would be to copy the file into some sort of RAM disk. Maybe QuickTime can play the movie from a buffer in memory. I'll have to look at the APIs...

Thats certainly an interesting idea about the keyframe per frame. I'll have to try this once I get off this slow iBook and back onto my PowerMac.

qnxde · Sep 15, 2003, 01:48 AM

Do what I said and try MJPEG - you'll be pleasantly surprised.

iJed · Sep 15, 2003, 02:37 PM

Originally posted by qnxde:
Do what I said and try MJPEG - you'll be pleasantly surprised.

Yeah I'll be trying this once I get back on my PowerMac G4. I'm currently not at home and my iBook 500 is rather slow to play anything on.

iJed · 05:40 PM

Also what is the difference between motion JPEG type A and B?

I suppose I should probably Google this but I'm too lazy!

Edit: I've just tried MJPEG type A and the difference is truly incredible. On my old iBook, which stutters when playing a small MPEG, I can play a simple movie more than 100 times faster than normal without any stutter or flaws!

Volanges · Sep 16, 2003, 01:51 PM

this codec just came out but I've not used it:

http://www.bitjazz.com/sheervideo/