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basic compositing using rvio

Matthew Levine

September 01, 2015 14:26

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We've had a couple of our users ask if they could composite (A over B) two images when encoding from EXR to a movie format (like H.264).  Typically, when you try to create a movie from source images that have a lot of transparency, the images are comp'd over a black background.  My guess is this is probably done by the encoder by default.  However, our users want to specify a different color like gray.  They don't necessarily need to do any real compositing, like providing separate sets of images, but they would like to alter the background color when encoding a movie.  Is this currently possible with rvio?  I didn't see anything obvious while looking through the help.

(EDIT: this is currently done by comping the images in Nuke and then sending them off to rvio, it would excellent to skip that step)

Thanks, 

Matt

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4 comments

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  Jon Morley September 03, 2015 07:43

  Hi Matthew,

  There is not a way to do that in one call of RVIO I am afraid. At least not as I understand your goal. You can create a session file either interactively in RV or programmatically with rvSession.py which could be fed to RVIO for the desired result.

   

  I am not 100% sure I follow, but perhaps the following will work for you:

  1) Create session interactively in RV

  rv <source_with_alpha>.exr solid,red=0.5,green=0.5,blue=0.5,width=<width_of_source>,height=<height_of_source>,start=<start_of_source>,end=<end_of_source>.movieproc -over

  Each term in <>'s should be replaced with the actual value as appropriate for the source you are using. Once RV comes up save the session.

  2) Create the movie with RVIO

  rvio_hw <session_of_two_layers>.rv -o comp.mov

   

  Is that the kind of thing you are looking for?

  Thanks,
  Jon

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  Matthew Levine September 03, 2015 07:43

  Thanks Jon!  That might be good enough for what we need.  We might want to script this up so we can better incorporate it into our pipeline, but I doubt it would be very hard to create this simple session file pragmatically.  I'm sure we can get a TD to do it.  Thanks!

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  Matthew Levine September 03, 2015 07:43

  dyac!  that should read "I doubt it would be very hard to create this simple session file programmatically"

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  Jon Morley September 03, 2015 07:43

  Great Matt!

  Please let us know if you get stuck anywhere.

  Thanks,
  Jon