updated 12:00 pm EDT, Thu August 20, 2009
iPhone 3GS May Have 1080p
Despite Apple's claims to the contrary, a test by a forum member at Weiphone suggests the iPhone 3GS may already have enough performance to smoothly play full HD video. By manually copying over videos using file transfer apps on a computer and the iPhone, the community member says he could play up to a 1080p (1920x1080) clip at 30 frames per second at up to a 35Mbps without any lag or stuttering. Although they don't show in the official iPod app, they work using Apple's built-in video player when called by a third-party program.
The playback is potentially sensitive to problems depending on the way the video was encoded but can support many clips encoded in H.264, including podcasts listed at the iTunes Store.
Such performance implies that Apple is intentionally limiting the 3GS to the same 640x480, 1.5Mbps video of the first two iPhone generations despite having the potential to support HD. It appears to confirm a previous device teardown that showed that, by itself, the Samsung ARM chip could decode 720p smoothly at least when running at its full clock speed. Apple downclocks the processor to 600MHz for heat and possible battery concerns but may have the help of the PowerVR SGX graphics core to assist in decoding clips.
What motivation Apple would have to do so isn't evident, but the limitations likely stem from the potential impact on battery life and free space. HD video typically requires much more processing power than standard definition footage and consumes much more space: even at iTunes' typical lower bitrates, a 45-minute TV show in 720p uses about 1.5GB of space. A 1080p version scaled upwards in bitrate would use more than double that amount.
Apple's video cables are also currently limited to component-out for HD instead of the HDMI format usually preferred for external video out.
If officially unlocked, the feature would nonetheless put the iPhone 3GS above even handsets that are known to officially support playing HD video natively, such as the 720p-capable Samsung's i8910 (Omnia HD). It would also give a likely third-generation iPod touch a potential advantage over the Zune HD, whose signature feature is an NVIDIA Tegra processor that supports 720p video without affecting battery life. [via iLounge]