Learning Quartz Composer Part 1
More babysteps with Quartz. I set about trying to make a split-screen effect quartz effect which would replicate any video 9 times within the same screen. (This was to fulfil a request for someone who wanted me to alternate between fullscreen and 9 videos on a video wall made up of 9 screens, where a hardware matrix switcher would usually be used, but couldn’t be on this for some reason.
“Can’t you use 9 billboards and make them 1/3rd the size of the screen and position them accordingly?”
and even offered up an example file.. http://vade.info/9.qtz
Bingo! Coming from traditional video editing land, I hadn’t even been able to grasp that creating a new billboard effectively creates a new image that can be composited. So then, loaded with new brain juice, I set about transforming the patch so it would work within VDMX.
There were a few barriers:
1- For parameters within a Quartz patch to show up as visible, adjustible parameters within VDMX, a process called ‘adding a published input’ needs to be done. The above quartz patch was set-up to take a webcam input and replicate that 9 times. This needed to be changed to a ‘published image input’, which would mean when loaded as a VDMX effect, it would take any movie playing in that VDMX layer, and apply the replication and compostion effect to it. The adding a published input process is documented on the VDMX wiki.
2 - Although the webcam split evenly into 9 screens, when taken into VDMX the 9 clips had plenty of overlaps. This became a tedious process of working in quartz with webcam version, dimension mode on auto-height, adjusting the input parameters for each billboard a certain amount, then adding the VDMX input back in, importing to VDMX and testing what it looked like now. (If anyone has any advice on making composition arrangement in Quartz less painful, love to hear about it! ). Eventually, I managed to make a VDMX effect that can quickly turn any 16:9 clip into the desired 9×16:9 clips, in a 16:9 screen.
And here it is: http://www.skynoise.net/quartz/9screens16_9.qtz
( Dump that into your Quartz FX folder of VDMX and it should show up as an effect for any layer ).
The transitions used in VDMX are available as quartz files to play with in the VDMX composition mode folder. Open them in Quartz, saving under a new name and playing around with them makes it fairly trivial to make new transitions. If you add something else useful from Quartz to them, or wish to have real-time access to any of the parameters of the transitions ( eg opacity / angle, etc ), these parameters can be published as inputs using the above methods, and then they show up as VDMX friendly parameters that can be mouse dragged or audio synced etc.
A Next Batch of Quartz Problems:
Planning to work through these over time, but figured I’d list them here, in case any pointers fly in…
- Is it possible to select an anchor point for rotating a clip in QC? (So that for example, a point well below the screen could be used as the centre of a circle that passed in an arc across the top of the screen.) I found the anchor.qtz example patch which seems more related to anchor points in HTML pages, but maybe there’s a way of using it? And the ‘Image Transform’ effect has a rotation parameter, but no adjustible anchor point?)
- How can a slider transition be adjusted so that both clips move in sync, not just one sliding in over the other?
- Related to the slider sync – how to do seamless tiling? Am guessing once the sliding is figured out, use mirrored images at the edge of an image, to enable a seamless horizontal or vertical scrolling loop?
- Is it possible to include video masks on a layer, not just image still masks? Is it possible to use masks that effectively create blank / alpha channel space around pixels in a layer?
- Some day : separate photoshop layers with adjustible depth of field blur in sync with z depth?
- Some day II : sliders that create exponentially smaller (replicated) slices of a video.
- Some day III : more sliders, that create puzzle slider type FX, but with adjustible zooming and scaling on the pieces – so they stay the same puzzle size, but are more or less zoomed in.
So if you’ve got any advice, suggested reading / plug-ins etc about any of the above – please get in touch.