It's no secret that streaming music, video and media-heavy websites are putting a strain on our wireless carriers, and placing bandwidth in short supply. Unlimited data plans from the likes of AT&T have already been phased out, with Verizon Wireless rumored to be following suit. Smart phone users just can't seem to catch a break.
average of 1Mbps — 125KB/s — across some of America's most popular carriers. What this means is that, in terms of streaming, developers don't have all that much bandwidth to play with; cell phone signals are never consistent, and tend to rise and fall depending on your location. Problems are further impacted by factors like congestion, or even the type of cellular radio within your phone.
A great deal of work must be done by developers to ensure their apps can stream comfortably within these confines, while still delivering a consistent experience to consumers in an inherently inconsistent environment. That being said, every app in your phone's market place handles that wireless bandwidth differently — an important factor to consider in conserving your 3G usage.
For a simple example, let's take a look at the audio bitrates for some of the most popular streaming radio and music services available on smart phones today.
|Low Bitrate||High Bitrate||Encoding|
As you can see, most streaming services use similar bitrates on mobile devices, jumping between 64kbps and 128kbps depending on the available bandwidth. Ideally, apps will prefer to stream audio encoded in a lower bitrate whenever possible; a file encoded at 64kbps will not only load faster, but likely tolerate cellular fluctuations and congestion much better than a higher-quality stream. Last.fm, Spotify and Grooveshark, however, all have the option to force a higher quality, 128kbps stream over 3G, should you so desire.
In Pandora's case, you might assume the service's default 64kbps stream would sound worse than a higher-quality 128kbps from Last.fm. You'd be wrong. Pandora encodes its songs using a High-Efficiency AAC codec, compared to the MP3 encoding used with Last.fm. A 64kbps HE-AAC file is said to sound on-par with a 128kbps MP3, providing the same level of quality, but at half the bandwidth.
You probably know where we're going with this. Those of you with sizeable bandwidth caps, might be tempted to opt for a high-quality, MP3-encoded stream, logically assuming that the quality will be better. But in reality, you're actually using more bandwidth than you need when compared to a comparable 64kbps HE-AAC encoded stream. If you're looking to keep the usage down, Pandora, Rhapsody and recent entrant mSpot are all excellent choices for low-bandwidth tunes, yet still manage to sound decent over 3G.
However, things get more difficult when you factor video into this equation. Not only is an audio stream smaller, but also far less complex than accessing your Netflix queue. The extra bandwidth required of streaming video introduces some serious issues when faced with the slow and congested speeds of a 3G network.
To put all this into perspective, Apple has put forth what they call their HTTP Live Streaming specs, which dictates how the quality of video that can be broadcast over a cellular 3G network. These specs apply to any developer looking to include a video streaming app in the App Store, from Netflix to Hulu, and reveal some interesting facts. For example, Apple's guidelines state that a video's audio stream should never have a higher bitrate than 40kbps. Curiously, this is across both 3G and Wifi networks. The reason here is obvious, however — a smaller audio stream means more video can be transmitted, particularly important in the case of the iPad.
As for other platforms, the bitrates and performance of mobile video isn't quite as clear. Both Vimeo and Youtube have their own mobile sites that have been adapted for 3G use, and run reasonably well on Android devices. Without Apple's AT&T-inspired limits, the streaming bitrates for these services are undoubtedly higher, though probably not by much. Verizon's V CAST is a good example of this; at an average bitrate of around 400kbps, an hours worth of television would require 180MB of data. Compared to Apple's limits, it would be trivial to fill a 500MB monthly cap in a matter of hours.
The point here is that not all mobile streaming services are made equal. The so-called estimates that wireless companies use to advertise their mobile data plans are poor representations of real-world use, and if you're not careful, you can burn through your monthly cap faster than you think. While we all would love to live in a world of unlimited data, it's clear that's not exactly possible right now. However, knowledge is power, and knowing how much bandwidth your audio or video streaming apps are pulling from the cloud is your best defence against exorbitant overages on your monthly bill.
Lead image via Flickr user state.