What Flash does to iPhone battery performance

Battery performance across mobile devices is something of an interest point for me. I think it’s largely due to the fact that almost everything in this industry conforms to Moore’s Law (doubling in speed / performance every 12 months), expect for battery performance.

Any increase in efficiency is quickly sucked-up to assure the performance of power-hungry innovations such as 3G/4G radios, backlight touchscreens, wifi, more powerful processors etc. As a result, battery performance hasn’t shifted much in the last few years. In fact, poor battery life remains one of the most common criticisms of the iPhone. Most smartphones will struggle to give you more than a day of power. I remember by old 6-series Nokias lasting 4-5 days.

I was interested to read Steve Jobs’ recent post, defending Apple’s decision not to support flash across the Touch, iPhone and iPad.

In it he reference’s the drain on power resource for the iPhone from decoding video at a software level (as performed by Flash).”

“To achieve long battery life when playing video, mobile devices must decode the video in hardware; decoding it in software uses too much power. Many of the chips used in modern mobile devices contain a decoder called H.264 – an industry standard that is used in every Blu-ray DVD player and has been adopted by Apple, Google (YouTube), Vimeo, Netflix and many other companies.

Although Flash has recently added support for H.264, the video on almost all Flash websites currently requires an older generation decoder that is not implemented in mobile chips and must be run in software. The difference is striking: on an iPhone, for example, H.264 videos play for up to 10 hours, while videos decoded in software play for less than 5 hours before the battery is fully drained.”


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