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When your frame rate goes down, and the video starts lagging, it is important to be able to analyse where it can come from. Today we’re going to look at some information we can use to troubleshoot this. Roughly, the way our application works is the following: at each pass, we read  a video frame from the disk if needed, decode it and then send it to the GPU (the Graphic card’s CPU) together with all blending and effect operations. Then we ask the graphic card to flush all operations (that is actually processing all pending graphical instructions) and present it to the display. If you look at the bottom of the user interface window in either NuVJ, GrandVJ or MediaMaster, you will notice that there are two numbers constantly updated. Something like: Graph: 400.00 Total: 60.00 These numbers indicate the speed at which the engine does its rendering.

Note: This is an un-edited post originally written by Modemasters (G’day Adelaide!) on VJ Forums, but we thought it might be worth having a copy here. Although focused on the MPD24, it’s a good general overwiew of using GrandVJ with Ableton Live and MIDI controllers. Huge thanks to Modemasters for having done such a clear Tutorial! This tutorial involves using an Akai MPD24 Drum Controller in conjunction with Ableton Live as a host sequencer and ArKaos GrandVJ as a ReWire slave for MIDI synchronised video clip launching. It is assumed that you are familiar with the basic operation of an MPD24, including edit presets and controller parameters, and basic MIDI mapping within Ableton Live.