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Wednesday, February 18, 2009

Multimedia Storage

Another good question from a reader. This person works in a military environment with some very particular requirements for how multimedia assets are treated during development. Because of that he's in the position of having to determine how much disk space will be needed during development. He's seeking help to answer ...

Are there formulas you use to determine disk space needs during development of multimedia training?

My first reaction was - just buy more disk space. It's cheap. But the context here does quite allow for that. It's pretty interesting to hear about development in a military environment.
Military multimedia development is contracted to 3 or four different companies who put development teams here on the base to research and develop the courseware using government provided computers, software and networks. Under their contracts everything becomes the property of the government once they receive tasking and begin developing a course (and I do literally mean 'everything'). It's pretty much set up so that each contractor has a 'folder' on the development network - they subdivide within that folder as necessary depending on how many courses they're working on, etc.

The govt prefers that while it is ok to work on your local machine, end of work day or finished items should be kept on the development network. At the moment we use VSS to manage assets - it allows check in and check out and tracks file use. We are just about to move to Adobe's Version Cue.

Additionally, once a course is completed and delivered it's not removed from the network storage - the govt takes over the maintenance and any updating of the course - and on top of that we're required to maintain backward versions of the course. So three months from now if a course is revised in some way we're required to keep the old version as well as the new one. so even our backup storage becomes quite complicated! (requirements state we're to keep 3 back)

Unfortunately for us, the military isn't able to simply add X TB to its storage design. They are required to predict growth, show usage and justify that addition.

So, I have to supply them with storage figures and growth predictions.

I've used various approaches and have based things off of prior work. But in most cases, it is definitely pure guesswork.

I should also add that this is mostly a situation applicable to the development side of the house. Once you have a finished product and it's been cleaned up and put in a 'run time' condition for the LMS, size (while still important) does not become that much of a storage issue.
I know that a lot of this have gone through this kind of thing, especially in large development projects. I'm curious what formulas or general rules of thumb that people have for total development storage requirements. For example -
X minutes of finished video * A MB +
Y minutes of finished audio * B MB +
Z minutes total runtime * C MB
Any such formulas out there?


Jeffrey Kafer Voice overs said...

I can't speak to video, but audio will run you about 5MB per minute when recording at 16bit 44k Mono.

Anonymous said...

Here are some general guidelines that we use for video. Keep in mind that with video there are many compression options and techniques that can have significant impacts on file size, so these are just guidelines.

Uncompressed Video (per minute)
Internet Lo-res (320x240) - 263 MB
Standard Def TV (640x480) - 1.054 GB
HD 720p (1280x720) - 3.164 GB
HD 1080i/1080p (1920x1080) - 7.119 GB

Compressed Video (approx.)
NTSC DV50 - 448 MB/min
HDV 720p - 160 MB/min
DVCProHD 720p - 880 MB/min
DVCProHD 1080i - 1.96 GB/min
Apple ProRes422 720p - 1.25GB/min
H.264 720p (default) - 25 MB/min
H.264 (640X360) - 6.8 MB/min

Tony Karrer said...

This is a good starting point. A big part of the question is:

How much do you keep around during development?

Anonymous said...

The number of assets attributed to development vary by the output in my experience.

Interesting analysis question. I would venture that the best way to answer this in an environment would be to take a sampling of product archives and divide the space by a common variable (perhaps seat hours). By using a large variety of output types and adding a standard growth factor you'll probably be as far ahead as by trying to nail specificity and calculate by the type. It simply varies too much from design to design to get an accurate gauge that way.

I do recommend, however, that a standard storage schema is established. I've seen many inconsistencies in the commercial and government environments that end up causing problems in the long run. An ordered structure can help to clean out some of the stuff that isn't really necessary for the archive (cutting room floor).

The main goal of the structure I use is segregation of working prep, precompiled, and deployment build files. I don't want to see redundant publish or cross pollution between my segregations.

I use this structure:


The build is the customer build as it will be deployed. If I'm adding scorm structure this is preplanned and my publish processes deposit the compiled media or final destination media into the appropriate folder (SWF, FLV, MP3, etc..)

Source is the authoring source. FLA's or other authoring structures go here.

Prep is the media prep. I divide this into two main sections (1) raw (2) prep source. The raw folder contains any logged but unprocessed audio, video, or images. Prep source is any source files I use to process the image, audio, or video. These might be sound forge data files, video source (Premiere / AfterEffects), 3D source, PhotoShop, Fireworks, etc..

I find that it's really helpful to provide a simple top down structure for whole project archive.