Requirements: Digital Fusion 3.1, DFX+ 3.1
Flow: N/A
Images: N/A
Archive: N/A

Using the cache to disk option in a large flow can dramatically increase performance of a project inside Digital Fusion. What the cache is actually doing is rendering every tool upstream of the cached tool, and saving the selected cache to disk.

The following is a collection of tips and issues with Cache to Disk.

1. DFX+ does not support disk caches, so do not try using them in this version of the program. Only Digital Fusion supports disk caches.
   
   
2. Don't cache every tool in the flow, just key tools that have upstream areas that need a speed boost.
   
   
3. Generally you will want to cache anything that is processor intensive (glows, blurs, etc.) or very large branches of a flow. You need to be sure that you are finished in that area, as it will lock the tools upstream from the cached tool.
   
   
4. You do not have to prerender to place a disk cache on a tool. You can enable a disk cache and not render. As each frame is processed it will be placed in the cache, at the quality and proxy level of your current interactive frame (unless a cache already exists of that frame of a higher quality).
   
   
5. Network rendering of disk caches is possible, all paths need to be visible to all slaves, including the 'preferences/paths/cache to disk' folder, which is where the cache will be stored. Your flow also needs to be loaded from a drive visible to all slaves i.e. c:\flow.flw would not work for a slave in a remote location, \\computername\c-drive\flow.flw will, provided the c drive is shared.
   
   
6. There is an issue in 3.12a and previous versions, where sending off more than one network cache at a time will not work 100%. Currently, all cache to disk over the network uses the same flow name, and if sending off more than one, there is a possibility of overwriting the next queued flow. So you may end up missing a cache even though you have sent it to network render. To avoid this, just be sure to let the first network cache finish before you send off the second one.
   
   
7. If your cache is empty at a given time, and you are in proxy mode, you will get a proxy frame saved into your cache. If you want Fusion to produce a full quality frame while working interactively, you have to check Hi-Q, and disable proxy. Fusion can only save what it renders. If you pre-render your cache, you can produce a full range of final render quality frames for your cache.
   
   
8. If the cache at time x already has a frame stored in the cache it will only replace that frame if the current mode is of a higher quality than the mode of the software when the frame was saved. in english I mean that a full resolution hi-q frame in the cache will not be replaced by a proxy frame, but a proxy frame will be replaced by a full resolution frame.
   
   
9. Always leave Lock Branch enabled when you create a disk cache. Unlocking the branch will make you crazy. It is possible to unlock the branch, however it will drive you nuts, as the cache and the upstream tools will be different and out of sync. Just not a good idea.
   
10. Always leave RAW files enabled when you create a disk cache. Only the default .raw format files contain the necessary info to handle proxy sizing correctly - anything else, and not only will you likely get proxied frame issues, but you'll get HiQ/non-HiQ problems, you'll lose any extra channels or 16 bit depth info, maybe field problems, etc etc.