One of the most confusing things about digital video editing is the storage requirement. In this page I will help you better understand just what kind of storage you will need for your video productions.
Finally digital video makers have a range of choices for storing their digital video files. Todays new hard drive and RAID technologies combined with larger, cheaper drives have made desktop video editing more affordable then ever!
You can never have too much storage
DV compressed video requires 13GB per hour of footage. While this may not seem like a big deal to you today, it sure was just a few short years ago. Back in 1998 a 9GB SCSI drive would cost you over $1500! And if you wanted to create great looking video, you had no choice but to invest that kind of money. Today’s Ultra ATA66/100 EIDE drives are almost as fast and they are a fraction of the cost.
For single stream DV (ie Pyro, Edit DV, DV200, DVnow) a single ATA EIDE drive is enough. For home use you can even use a single EIDE drive for your system. Just make sure you have separate partitions for your software and the video.
It’s the throughput that matters
Seek times and RPM and peak transfer rates mean not much for video production. All we care about is sustained throughput. We don’t care about the highest specs of the drive. We only care about the minimum. If the sustained data rate of the drive dips below the required transfer rate for our video, the result is jerky playback, messed up audio and dropped frames. Given today’s technology, there is no excuse for this. When in doubt, get better storage then you think you will need.
A single EIDE drive will get slower as it fills with data
This is because a hard drive is a spinning disk. Back when we all had turntables and records, this was very easy to explain. If you placed a penny on the outer edge of the record, it would travel a much greater distance in a single rotation then a penny placed near the label on the inside of the LP. More distance over the same period of time equals greater speed. Hard drive is the same: a single EIDE drive will get slower as it fills with data.
VideoRAIDs use a special technology called Zone Striping. This matches up the inner tracks of one drive with the outer tracks of the second drive. This is how a 2-drive VideoRAID can achieve 20 megs per second substantiated throughput over the entire capacity of the drive.
Real-Time editing requires REAL storage
This is really the end result of above mentioned. Today’s awesome real-time cards can do great stuff, but only if they have adequate storage. You need 3 times the data rate of a single stream of video to support dual stream editing. DV is a fixed 3.5 megs per second. So Real-Time DV editing requires a sustained data rate of 10.5 megs per second.
Today’s lightning fast ATA100 EIDE drives will support this data rate when they are less then 75% full (Ultra66 drives up to 50% full). As your storage begins getting slower, your video editing system will get sluggish and unresponsive. As your single EIDE drive continues to fill up and get slower, it will eventually effect the output quality of your video.
RAIDs are GREAT for video
RAID stands for Redundant Array of Independent Disks. What it means is that 2 or more drives are grouped and formatted together in order to provide greater storage and performance. There are several different types of RAID. Servers typically use RAID 1 (mirroring) or RAID 5 for data protection. For video we use something called RAID 0 (striping) for speed. The computer sees the striped drives as a single drive and the data is split between the drives, making the sustained throughput much higher. Two 30GB drives striped together result in 60GB of storage.
If you plan on creating your own DVDs, you need plenty of storage
At best quality a single sided 4.7GB DVD holds just under 2 hours of video. To make a 2hr DVD is going to require a very large amount of disk space. Here is a little math exercise that will explain just how much storage you will be needing.
- If you are starting with DV footage, you need 13GB per hour of video.
- This means a 2 hour DVD is 2 x 13 =26GB of footage.
- Add in the extra unused footage and it’s more like 3 x 13 = 39GB.
- Figure that you’ll be adding some extra graphics and audio tracks. Let’s say another 2GB for these.
- Now you need room for the MPEG2 footage for the DVD, that’s 4.7GB more.
- If you plan on creating the DVD in a folder first (we recommend this) that’s another 4.7GB.
- Add it all up and it comes to over 50GB of high speed video storage to make a 2 hour DVD!
Which storage system should you buy
If you want the lowest possible cost, then the FastTrack is by far and away the winner, but please note, you will have to mount and configure the RAID. This is not a terribly difficult procedure, but it does require some effort. You may run into some mechanical, not technical.
Source : http://www.aboutvideoediting.com
Filed under: 1 |
Noor Rochim 
Leave a comment