Trends in Image Storage
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Feature: What does Data Storage have to do with digital SLRs and camcorders ?
Idea:Everything - as the speed of recording and capacity of data cards is pivotal

Storage of digital image data, the huge amounts of its data streams and the speed with which those streams both can be written and read, has been and continues to be one of the pivotal constraints that determines the overall value and effectiveness of many cameras and camcorders. I can remember just 10 years ago Sony offering to users a Mavica camera that recorded directly to floppy disk. This was followed by Canon, Nikon and a flood of of other digital cameras that could record nearly 1MPixel images to compact flash cards of 8, 16, 32 and a whopping 64MB in capacity.

Meanwhile, video camcorders used tape recording technology - the only media that could effectively cope with the hundreds of megabytes accumulated even with a modest 320 x 240 pixel video image. Lets just do the math:
Total Bytes = 320 x 240 bits/8 bits/byte * 24 frames/sec * 60 sec/min * 20 minutes
Total Bytes = 276,480,000 bytes/20 minutes = 276MB per 20 minutes of video recording
Record at TV screen capacity of about 640 x 480 pixels and the video recording requirements quadruple to over 1GB per 20 minutes of recording. Add in very cold, humid, or dusty conditions and getting "good tape" was no trivial matter.

In short, the challenges of recording the digital images has been as much a daunting task as perfecting image sensors and digital controller chips to orchestrate the whole process. In fact, some would argue that the sensors and digital processors have been more than equal to their tasks. The real limit has been in the capacity and then speed of the storage used in digital cameras and video camcorders. This is why the new storage technologies are of interest, especially for video camcorders.
What you see above is a 256GB SSD - Solid State Drive. It has a capacity of 256GB and has an average access speed of 0.1ms. I have highlighted in yellow some of its other important operating specs. Lets compare this SSD-Solid State Drive to a regular hard disk drive-HDD used in most PCs, and particularly notebooks(but also appearing in some digital cameras). Both drives will use a standard SATA connection to the device, this allows high speed read and write of data at 50 to 70MB/sec. The HDD-Hard Disk Drive will be a 7200RPM, 3.5" drive used in many laptops(better performer is placed first):
Maximum capacity - HDD 1000GB, SSD-850GB - not much difference here
Average Access Time - SSD 0.1ms, HDD-7MS - huge 70x speed advantage to SSD
Transfer Rate - HDD-75MB/sec, SSD-50-65/MB/sec - HDD has 15-20% faster data rate
MTBF - SSD 1Million hours, HDD - .6Million - advantage to SSD but note cautions below
Cost - HDD $1/GB, SSD $10-15/GB - decided advantage to HDD
So in just these five factors one can see the major trade-offs between HDD-Hard Disk Drives and SSD as used in photo equipment. However there are some secondary factors to take into account.

First, the technologies in SSD using Flash memory are relatively new where as HDD technology is at least 40 years old. Thus one should expect faster improvements and cost savings to be found in the SSD devices. Second, there are some performance characteristics harder to quantify comparatively that give additional advantages to SSD. Power consumption for SSD drives is 30-80% lower than HDD giving longer battery life and less heat. The SSD has virtually no noise. And finally the SSD is much better able to stand falls and high G force shocks than a hard disk. That is why SSDs are used in military and industrial applications.

On the downside for Flash-memory based SSD which have been cited throughout this note is the fact that repeated writes to a memory cell in a Flash memory device can lead to write failures. Typically, the failure occurs after 15 million write cycles (for high usage files such as log files, file allocation tables, and other commonly used parts of the file system exceed this over the lifetime of a typical computer). However, new write leveling algorithms are improving this factor.

So SSD disk drives are already appearing in laptops (the expensive option in the new MacBook air and the OLPC-One Laptop Per Child). Likewise in photo equipment both high end camcorders and SLR digital cameras are using SSD. It appears the constraint for wider usage of SSD will be the cost per GB and some other competing technologies like compact flash cards and more importantly SDHC cards popular in many point and shoot cameras, digital SLRs, camcorders and even laptops.

See here for a comparison of SSD versus the popular SDHC memory modules used in many digital cameras and camcorders. Again this trade-off between SDHC and SSD is a cost (advantage of about 8 to 1 for SDHC) versus speed and capacity (advantage of about 4 to 1 in both cases for SSD); however with both technologies have better reliability over HDD based devices.


Expect your digital camera and especially camcorders to add impressive speed and capacity in the next few years through both SSD drives and other technologies. But also expect faster SDHC cards used in both digital cameras and camcorders. What does this mean to you, the photo enthusiast? Camcorders in 1-2 years time that are able to store 100-200GB and the same for Digital SLRs. Watch for more cameras that will be able to to do things like the Casio EX-F1 currently does but at longer intervals and greater base image size.

Thus, expect bracketing and sports clips at 10-30 images per second for larger than 6MPixels and longer than 3-5 second bursts. In sum, there will a lot of performance improvements in digital camera and especially camcorders in the next 1-3 years; much will be in the back end where speed and capacity of recording images will improve by big factors of 50% or more for each new product intro. But expect very fast storage to appear everywhere in electronic products - mobile phones, handhelds, laptops, etc.

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