Video: Finally High Profile H.264

Section by Brian Klug

There are a few things different with video capture on the iPhone 5 thanks to improvements to both the ISP inside Apple’s A6 SoC, and also software UI changes. First off, because the iPhone 5 display is now 16:9, there’s no cropped view by default or aspect-correct view with letterboxing for video capture. Instead the iPhone 5 video capture window takes an iPad-like approach with transparent UI elements for preview and shooting video.

What’s new is the ability to take still images at 1920x1080 while recording video by tapping a still image capture button that appears while recording. This is a feature we’ve seen onboard a ton of other smartphones and works the same way here. Note that you can’t magically get a wider field of view or the whole CMOS area while shooting video, it’s essentially dumping one frame from video capture as a JPEG instead of into an H.264 container.


In addition the iPhone 5’s tweaked Sony CMOS still uses a smaller center region for video capture. The difference in field of view is pretty big, but nothing that users haven’t already dealt with in the past.

The iPhone 5 brings two main things to video capture. The first is improved electronic image stabilization tweaks and improvements to ISP. The difference is visible but not too dramatic unless you know what you’re looking for. I would wager most users won’t notice a huge step forward from the 4S but if you’re using an iPhone 4 this will be a marked improvement.

The other improvement is video encoding. The iPhone 5 now shoots rear facing 1080p30 video at 17 Mbps H.264 high profile with CABAC. This is a huge step in encoding from the relatively absurd 22–24 Mbps baseline H.264 that the iPhone 4S would shoot at 1080p30. The result is vastly more quality per bit on the iPhone 5, for a big reduction in storage space per minute of video. I did some digging around and found that the A6 uses an Imagination Technologies PowerVR VXE380 for encoding and VXD390 for decoding, which is what I thought was in the previous SoC as well but perhaps wasn’t clocked high enough for encode at high profile. This brings the iPhone 5’s encoder on paper up to match what I see other smartphones running their 1080p video at as well (17 Mbps high profile).

On the front facing camera Apple is shooting 720p30 at 11 Mbps H.264 baseline, as opposed to the VGA at 3.5 Mbps that the 4S shot. Interestingly enough both front and rear shooting modes still are just mono audio, 64 kbps AAC. I would’ve liked to see stereo here since almost all the competition is shooting stereo, and it’d put those 3 microphones to use.


To get a feel for video quality, I stuck my iPhone 4S and iPhone 5 in my dual camera bracket with pistol grip and made a series of three videos. I then combined them and put them side by side for ease of comparison. I’ve uploaded the result to YouTube, but you can also grab the original videos (548 MB zip) if you’d like from the site directly without the transcode.

Overall the most dramatic improvement is the front facing camera, which is obviously night and day. Better image stabilization is noticeable while I’m walking around being intentionally shaky, but nothing hugely dramatic. The main rear facing video improvement seems to be an increase in sharpness (watch the power lines and wires in the native resolution version) and slightly wider field of view. That’s to say nothing of the fact that this quality comes at a bitrate that’s lower than the previous version but with better encode settings.

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  • A5 - Tuesday, October 16, 2012 - link

    Double the browsing time while moving to LTE and roughly the same in everything else despite double the performance is pretty impressive. Reply
  • rarson - Thursday, October 18, 2012 - link

    I'm pretty sure they mentioned about a million times that "this is the new paradigm blah blah blah, where if you use heavy processing power more often, the battery life will diminish faster" (I'm paraphrasing here). I'm fine with that. The iPhone 5 shows some pretty impressive battery life in light workloads and doesn't actually do all that bad in heavy workloads despite how much number crunching it's doing, even though it might actually tank the battery life down to less-than-4S levels.

    It's a tradeoff: you get more power or longer battery life, depending on how you use it. The article paints this as a bad thing, but I disagree; it's obviously making much more efficient use of the hardware. Because of that, I definitely think the battery life overall is better, even though sometimes it might be worse. And you're still getting a lot more number crunching for the watts used.
    Reply
  • Center - Tuesday, October 16, 2012 - link

    In the intro, the screen specs on the iphone 5 is listed as 1136x960.. should be 1136x640.

    But great article as always, Anandtech!
    Reply
  • Krysto - Tuesday, October 16, 2012 - link

    I hope we'll see the same kind of thorough review of Samsung's Exynos 5 Dual chip, Anand. Reply
  • ltcommanderdata - Tuesday, October 16, 2012 - link

    Isn't TI supposed to become the first shipping Cortex A15 SoC? I expect Anandtech to thoroughly review the first Cortex A15 SoC. There shouldn't be a need to go into the same detail (on the CPU side) for every subsequent one unless preliminary tests show something significantly different. Reply
  • Kidster3001 - Monday, October 22, 2012 - link

    Samsung and Qualcomm do not ship generic ARM chips. They purchase licenses to use the ARM instruction set, not the chip design. Their chips are highly customized and perform differently.

    Using your logic to just review the first A15 class chip and consider the rest to be comparable is similar to just reviewing the first new car to be released every year and assume the rest will be comparable.

    btw, TI is getting out of the business. I doubt they will ship first, or ever.
    Reply
  • A5 - Tuesday, October 16, 2012 - link

    Considering the fact that Krait got several articles here, I'd imagine that whatever the first shipping A15 chip is will get significant coverage. Reply
  • Wurzelsepp - Tuesday, October 16, 2012 - link

    Great review, you really have to give Apple credit for building an amazing SoC.

    It's interesting to see how well the Adreno competes with SGX-543MP3, the new Nexus 4 with this GPU is going to be amazing.
    Reply
  • Krysto - Tuesday, October 16, 2012 - link

    One thing both the iPhone and the Intel Atom processors will keep lacking for a year from now, will be OpenGL ES 3.0 support. Apple might bring it to the new iPad 4 this spring, but the iPhone won't have it until the next iPhone, in the fall of 2013, obviously. Same with Intel, they won't be supporting it at least until end of 2013.

    In the meantime both Adreno 320 and Mali T604 are supporting it, and will come out this fall.
    Reply
  • darwinosx - Tuesday, October 16, 2012 - link

    A year from now and something 'coming out this fall". Right. Reply

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