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Video scratching

Hi everybody,
bearing in mind I have little idea about v really, can anybody tell me the current state of video scratching or at least random access in video clips in v4?

  • I read somewhere that mjpeg should be used only, but how easy is this to use in v4? Any success stories?
  • Is it feasible to convert all videos to mjpeg, easily?
  • Can you use just built-in objects for playback / random access?

Many thanks for all replies,

Matt

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http://www.loopit.org/

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basically vvvv uses whatever windows provides, so your questions is a generic “how to play videos on windows” question (with all the complications which arise).

if your video plays and scrubs fine in windows, vvvv can do similarily - just connect the SeekPosition and DoSeek pins on the FileStream node.

mjpeg is just one possible codec for the avi file format. it is not provided with a standard windows install - you need to buy the moonlight elecard decoder. with that codec installed, using it is as easy as any other avi file - you can use basically any program dealing with avi files to recompress your movies (virtualdub, vegas, premiere, aftereffects, whatever).

note that v4 can also deal with quicktime, so you can use quicktime codecs as well. from what i know there are some standard quicktime codecs quite capable of scrubbing.

also note that v4 will always stream videos from the hard disk, so if you want to have blazingly fast 60fps scrubbing experiences see the “looping” thread in FAQ AV

concerning quicktime files though you may notice that some of them scrub very well in the quicktime player but still not in vvvv. i guess this is because vvvvs quicktime playback is more a workaround (via directhow, which is not focused on scrubbing but rather playback) than a native quicktime-approach.

has anybody tried placing videos on a ramdisk and filestreaming them from there? maybe that helps.

the other possibilty is to load videos in the texturememory of your graphics card. of course the length is limited to the ram of your card, but depending on what you like to do this is an option, and its lightning fast. you can place for example10x10 videos and scratch each at an individual position and so on.
there are plenty of possibilites to control the playback position of you video, you can build your very own behaviours or use the allready built in options.

how do you plan to scratch the video? by mouse? touchscreen?

i did a little patch that can convert any incomming videostreams in an volumetric dds texture. so you can just load that texture and you got the video in your cards memory. you can even do crazy timeslicing effects in amazingly speed. it isnt finished yet but it i can provide it if you like to try.

I’ve done scratching in vvvv, again with mjpeg, picvideo and morgan are 2 more codecs both no hardware reliant, picvideo being the faster. If your playing back only 1 stream the performance is pretty good, no audio though, so bear that in mind.

check: elektromeier-KhronosProjector

it contains some example how to scratch to a volumetric dds texture, and a generator which generates such a texture out of video. note its still a hack and buggy.