Hopefully, KA-Lite will provide a low-resolution video compilation.Ī quick back-of-the-envelope calculation shows a few possible configurations of low-cost servers, starting at around $48. Serving low-resolution videos will reduce the required WiFi bandwidth and lower the demand on the Pi's CPU, thereby increasing the number of clients that can be served concurrently. Thus, transcoding the videos into lower resolution formats and reducing the unnecessarily-high audio quality will result in lower space requirements, as well as lower streaming rate. Many low-cost smartphones and tablets will not support such resolutions anyway (e.g., the Indian Aakash low-cost tablet has a 800x480 screen). While a few of the videos do require high-resolution (for example, a video clip displaying crowded Excel spreadsheets), many others do not. This brings us to a further cost reduction option: Many of KA-Lite's videos are high-resolution (1280x720) with CD-quality audio (44.1 KHz, stereo).
Assuming users are all concurrently streaming MP4 videos, this is impressive, especially noting that a few of the KA-Lite videos are encoded at around 2 Mbit/sec. The post mentioned that the Pi was able to serve 35 simultaneous wireless users. In a blog post yesterday, KA-Lite wrote about running a configuration similar to ours, but without the Wikipedia component. A primary school, for example, will be happy with a small subset that does not include the high-school-level-and-above material.
In our original prototype, we used a 64 GB card to hold all of KA-Lite's 4,000+ videos as well as a Kiwix database. The 64 GB SD card, which runs at about $50, is the most expensive component of our server. Many schools, however, will not need all 4,000 videos. To reduce the cost even further, we can use a lower-capacity SD Card. Less memory, however, will translate to fewer concurrent clients and possibly sluggish performance. If you only want to run a wireless server without a wire-line (Ethernet) option, then model A should suffice. Model A lacks the Ethernet port and has only one USB port instead of two, as well as only half the memory (256 MB vs. Model A costs $25, which is $10 less than the Model B. In our original server, we used the Raspberry Pi Model B, which costs $35. While $99 is cheap enough (about Nu 5,300), we can make our box even more affordable. To read more about this initiative (and find out what Sherig means), check out our project page. We recently put KA-Lite, together with Kiwix and other educational resources, on a single Raspberry Pi.
The most common software for serving offline Wikipedia articles is Kiwix. Our recent post about the $99 Khan Academy wireless server made quite a splash, leading to mentions on the official Raspberry Pi blog, comments by the good folks of KA-Lite, and then a few other places.Īnother major resource for education is Wikipedia.