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Old 27th December 2008, 22:03   #21  |  Link
chornobyl
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Encode the video and then corrupt or somehow delete the data for an I frame.
I don't know any easy way of doing this, aside from downloading a file through a torrent, and only letting it finish about 50%.
I think i do know how to do this stuff. Firs of all take some file(avi for example) encoded with some modern codec, and mark all frames as keyframes. Then play from arbitrary position back and forth. With rare keyframes this works much more interesting.
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Old 28th December 2008, 03:33   #22  |  Link
Zarxrax
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Originally Posted by chornobyl View Post
Firs of all take some file(avi for example) encoded with some modern codec, and mark all frames as keyframes.
How would one go about doing this?
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Old 28th December 2008, 17:05   #23  |  Link
chornobyl
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I know this isnt too smart but: i open file with VirtualDub, in import file dialor set RederiveKeyframes and change fourcc to something stupid like cvid(cinepak). Then change fcc back to "true" codec.
Also its possible to edit index with hexedit but i dunno how to do that.
Found that with x264vfw result is not impressive(it often outputs black screen with such totrures), wmv or xvid gives better result

Last edited by chornobyl; 28th December 2008 at 17:10.
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Old 29th December 2008, 20:50   #24  |  Link
Zarxrax
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Costs money, but: http://www.digieffects.com/products/damageintro.html
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Old 29th December 2008, 22:05   #25  |  Link
sumawo13
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I compressed part of a DVD in MeGUI to x264 using RAWAVC and made an Avisynth script to open the resulting .264 stream in VirtualDub using FFmpegSource(). When I seek in VirtualDub I get the desired effect, however, when I compress it looks fine.
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Old 30th December 2008, 01:29   #26  |  Link
Zarxrax
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I was just messing around in a hex editor and managed to get the desired effect pretty well. Basically first of all just cut the clip down so it is only the part you want. Then I opened it up in a hex editor, found the data relating to the first frame, and overwrote parts of it.
This hex editor works quite well: http://www.gero-net.de/avihex/
It has a function to jump to the beginning of an avi file.
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Old 30th December 2008, 09:50   #27  |  Link
Shinigami-Sama
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Originally Posted by chornobyl View Post
I know this isnt too smart but: i open file with VirtualDub, in import file dialor set RederiveKeyframes and change fourcc to something stupid like cvid(cinepak). Then change fcc back to "true" codec.
Also its possible to edit index with hexedit but i dunno how to do that.
Found that with x264vfw result is not impressive(it often outputs black screen with such totrures), wmv or xvid gives better result
this is because AVC does not belong together with VFW

also I second the hex editor
they're always a good option
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interlacing and telecining should have been but a memory long ago.. unfortunately still just another bizarre weapon in the industries war on image quality.
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Old 30th December 2008, 17:58   #28  |  Link
Reimar
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Additional options are using a fuzzer to damage the file, e.g. http://caca.zoy.org/wiki/zzuf which you can use to help at the same time fixing bugs. Keep in mind that different decoders will treat damaged files very differently.
Another well-know issue that can be used is non-matching idcts for en- and decoding or disabling the inloop filter for H.264 (once saw a video where this caused the sky to go pink...)
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