Storage and bandwidth are important concerns when selling digital goods. Digital content sales tend to involve the transfer of a significant amount of data. Video is especially data intensive, as even with modern compression codecs, file sizes still amount to hundreds of megabytes.
Even a moderately popular video download can quickly consume many gigabytes of bandwidth. Imagine our fictional Cranberry Merchant website decides to sell a short, 20-minute instructional video on Cranberry farming. The video is compressed using a high-performance H.264 codec and is sold as a direct download (as opposed to streaming).
The video quickly becomes a small hit and soon hundreds of amateur Cranberry farmers are clamoring to learn from it. Over 200 downloads were sold in the first day it launched. Each 30-minute, high-definition video file weighs in at 800MB. Video sales consumed 160GB of bandwidth in a single day.
Every web hosting provider offers different bandwidth pricing. Some claim to offer unlimited or several terabytes of bandwidth on their inexpensive shared hosting plan. Buyers beware: it's unlikely these services would allow the relatively simple scenario outlined in the last paragraph without seriously throttling connections or shutting off the hosting account altogether.
More serious hosting providers typically offer a soft capped bandwidth service included in the monthly hosting fees. Beyond this cap, the hosting provider usually charges an overage fee per gigabyte. As of this writing, $0.30 cents per GB is a common charge in these situations. In other cases no bandwidth is included in the hosting plan at all and all bandwidth is charged by the gigabyte. These plans typically hover around the $0.20 cents per GB range.
Let's assume our hosting provider offers 50GB per month in bandwidth, then charges $0.30 cents overage. In a single day our overage usage hit $33.00 and for the rest of the month we'll be paying for all the bandwidth we use. It should be noted, too, that service providers offering plans like this may also struggle to keep up and could end up throttling our customer's download connections if they occur all at once, or take other steps to reduce the load on their networks.
In the alternative example, where we pay for all the bandwidth, our first day of sales would rack up $32.00 in bandwidth fees at $0.20 per GB.
Bandwidth costs have implications for how digital goods are priced. Though most of the time the sale price should easily cover bandwidth charges, it is still very important to understand the pricing structure for our hosting provider. What if in addition to for-sale video products, we also offered several free instructional videos available for download or streaming? The consumption pattern of these videos will likely differ greatly and must be accounted in our costs. If using the same hosting system for website materials, including HTML, image files, and the like, this bandwidth must also be included. Ideally the sale price of our video would be able to subsidize the bandwidth required for the rest of the site.
As we can see, different situations can result in very complex cost structures. Some applications choose to offload heavy content files, like video, to a service like Amazon S3. At the time of writing, S3 charges begin at $0.17 per GB and can go as low as $0.10 for extremely high volume users. This is among the best available. Whether this is the most economical approach depends on a lot of factors, but the difference between $0.10/GB and $0.30/GB overage represents a potential two-thirds cost savings.
We will explore how to offload digital content files to Amazon S3 using Django, including securing them as private download links in the next section.