Archive for September 17, 2012

Monday, September 17, 2012

iPhone 5 Speed

Anand Lal Shimpi:

The A6 is the first Apple SoC to use its own ARMv7 based processor design. The CPU core(s) aren’t based on a vanilla A9 or A15 design from ARM IP, but instead are something of Apple’s own creation.

And he has benchmarks:

The fairly low clock speed also points to an increase in IPC (instructions executed per clock) over the Cortex A9 design. As I mentioned in our A6 analysis post, simple voltage/frequency scaling is a very power inefficient way to scale performance. A combination of IPC and frequency increases are necessary. If these results are accurate and the CPU cores are only running at 1GHz, it does lend credibility to the idea of a tangibly wider design.

Update (2012-09-20): Arnold Kim:

The total Geekbench 2 score comes in at 1601. Poole notes that the average score for the iPhone 4S is 629 and the average score for the iPad 3 is 766. A comparison chart of previous iOS devices can be viewed at Geekbench. The numbers seem to validate Apple’s claim that the A6 processor is twice as fast as the A5 and any previous iOS device.

Primate Labs:

Geekbench scores are calibrated using the 2003 entry-level Power Mac G5 as a baseline with a score of 1,000 points.

Update (2012-09-21): Anand Lal Shimpi:

The result is peak theoretical GPU performance that’s near identical to the A5X in the 3rd generation iPad. The main difference is memory bandwidth. The A5X features a 128-bit wide memory interface while the A6 retains the same 64-bit wide interface as the standard A5. In memory bandwidth limited situations, the A5X will still be quicker but it’s quite likely that at the iPhone 5’s native resolution we won’t see that happen.

How Apple Compresses Video Using JPEG, JSON, and <canvas>

David Bloom (via Hacker News):

<video> elements can only be played fullscreen on iPhone, which kind of ruins the desired effect of this inline video.

And on desktop computers, Apple’s Web site needs to work on all major browsers, but Firefox and Opera won’t support h.264 (and there’s no way that Apple would be willing to offer WebM or Theora fallback).

Apple used to solve this problem by sending a separate JPEG image for each frame of video and switching between them. You can see this in action on the Retina MacBook Pro “Features” page—which loads about 5 MB of JPEG images (using lots of separate HTTP requests) just for that 2 second effect.

For iPhone 5, they came up with a new approach that doesn’t require a separate image for each frame.

Apple is also using this approach to allow rotating the EarPods image, QTVR-style. It seems like the leading edge of Web development is always pretty crazy.

Fission 2.0

Paul Kafasis notes the release of Fission 2.0, which has an improved interface (with multiple windows), support for more audio file formats, batch conversion, AAC chapters, and more. The direct and Mac App Store versions are apparently identical except that the Mac App Store doesn’t offer upgrade pricing.