blocks|key|232320|text|我以前没有尝试过，也许这些是相关的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|232321|AVCaptureConnection+Class+Reference|offset|length|232322|CMTime+Reference中的|unordered-list-item|232323|Set+maximum+frame+rate+with+AVFoundation+in+iOS+5|232324|videoMinFrameDuration和videoMaxFrameDuration+(设置videoMaxFrameDuration)|style|CODE|232325|时需要|232326|232327|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/#DOCUMENTATION/AVFoundation/Reference/AVCaptureConnection_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40009522|1|https://developer.apple.com/library/mac/#documentation/CoreMedia/Reference/CMTime/Reference/reference.html|2|https://stackoverflow.com/questions/8101492/set-maximum-frame-rate-with-avfoundation-in-ios-5^0|0|0|Z|0|0|0|G|1|0|0|1D|2|0|0|L|M|L|1B|L|0|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|14|8|@]|9|@$D|15|E|16|1|17]]|A|$]]|$1|F|3|G|5|H|7|18|8|@]|9|@$D|19|E|1A|1|1B]]|A|$]]|$1|I|3|J|5|H|7|1C|8|@]|9|@$D|1D|E|1E|1|1F]]|A|$]]|$1|K|3|L|5|H|7|1G|8|@$D|1H|E|1I|M|N]|$D|1J|E|1K|M|N]|$D|1L|E|1M|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1N|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|S|$T|$5|U|V|W|A|$X|Y]]|Z|$5|U|V|W|A|$X|10]]|11|$5|U|V|W|A|$X|12]]]]

I haven't try this before, maybe these are related:

<ul>
<li><a href="https://stackoverflow.com/questions/8101492/set-maximum-frame-rate-with-avfoundation-in-ios-5">Set maximum frame rate with AVFoundation in iOS 5</a></li>
<li><code>videoMinFrameDuration</code> and <code>videoMaxFrameDuration</code> in <a href="http://developer.apple.com/library/ios/#DOCUMENTATION/AVFoundation/Reference/AVCaptureConnection_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40009522" rel="nofollow noreferrer">AVCaptureConnection Class Reference</a></li>
<li><a href="https://developer.apple.com/library/mac/#documentation/CoreMedia/Reference/CMTime/Reference/reference.html" rel="nofollow noreferrer">CMTime Reference</a> (needed for setting <code>videoMaxFrameDuration</code>)</li>
</ul>

blocks|key|2887921|text|经过一些修修补补，这个答案分成了两部分：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2887922|如何以60fps捕获帧|offset|length|style|BOLD|2887923|iPhone4s/5.1上的AVCaptureSessionPreset1280x720，帧持续时间设置为：|2887924|connection.videoMinFrameDuration+=+CMTimeMake(1,+60);*
connection.videoMaxFrameDuration+=+CMTimeMake(1,+60);|code-block|syntax|javascript|2887925|给你一个稳定的，超级流畅的捕捉。|2887926|如何将帧捕获到文件中@60fps|2887927|捕获帧是很好的，但您可能想要保留它们。|2887928|正如Brad在评论中指出的那样，将这些帧写入文件是另一回事。遗憾的是，无论我尝试什么配置，通过AVAssetWriter对帧进行编码都会导致捕获速率下降到观察到的~37fps，再多的alwaysDiscardsLateVideoFrames操作也无法改变它。然而，在这种方法中，每一帧都是从AVFoundation复制到你的应用程序，然后再复制回来，这对公交车来说是非常没有意义的，而且非常累人。幸运的是，AVFoundation有一个类可以消除这种往返过程：AVCaptureMovieFileOutput。|CODE|2887929|如果您让AVFoundation为您编写，那么iPhone4S可以捕获帧%2B音频并以60fps*的速度将其编码为.mov文件，而无需费力(约25%25的CPU)。|2887930|虽然60fps的视频捕获是一个很棒的功能，但我还是忍不住感到有点失望，因为AVCaptureMovieFileOutput排除了很多有趣的东西(例如，使用GL着色器的实时效果，没有帧丢失的录制开始/停止)。|2887931|蛋糕/吃掉它|2887932|*59如果您仍在运行iOS+5.0.1|2887933|entityMap^0|0|0|8|0|0|0|0|0|G|0|0|1B|D|2J|T|5N|C|6E|O|0|4|C|0|11|O|0|0|0^^$0|@$1|2|3|4|5|6|7|17|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|18|8|@$D|19|E|1A|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1B|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|1C|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1D|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1E|8|@$D|1F|E|1G|F|G]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1H|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1I|8|@$D|1J|E|1K|F|W]|$D|1L|E|1M|F|W]|$D|1N|E|1O|F|W]|$D|1P|E|1Q|F|W]]|9|@]|A|$]]|$1|X|3|Y|5|6|7|1R|8|@$D|1S|E|1T|F|W]]|9|@]|A|$]]|$1|Z|3|10|5|6|7|1U|8|@$D|1V|E|1W|F|W]]|9|@]|A|$]]|$1|11|3|12|5|6|7|1X|8|@]|9|@]|A|$]]|$1|13|3|14|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|15|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]]|16|$]]

After some tinkering, this answer has split into two parts:

How to capture frames at 60fps 

The AVCaptureSessionPreset1280x720 on the iPhone4s/5.1, with frame durations set to:

<pre><code>connection.videoMinFrameDuration = CMTimeMake(1, 60);*
connection.videoMaxFrameDuration = CMTimeMake(1, 60);
</code></pre>

gives you a stable, super smooth capture. 

How to capture frames into a file @60fps 
Capturing frames is all very well, but presumably you want to keep them. 
As Brad noted in the comments, writing those frames to a file is another story.
Sadly, no matter what configurations I tried, encoding the frames via an <code>AVAssetWriter</code> caused the capture rate to drop to the observed ~37fps and no amount of fiddling with <code>alwaysDiscardsLateVideoFrames</code> could change it. However, in this approach every single frame is copied from AVFoundation to your app, and then back again, which is quite pointless and very wearing for the bus. Luckily, <code>AVFoundation</code> has a class that removes this round trip: <code>AVCaptureMovieFileOutput</code>.

If you let <code>AVFoundation</code> do the writing for you then the iPhone4S can capture and encode frames + audio to a .mov file at 60fps* without breaking a sweat (~25% CPU).

While 60fps video capture is great feature, I can't help but feel a little disappointed as <code>AVCaptureMovieFileOutput</code> rules out a lot of fun things (e.g. realtime effects with GL shaders, recording start/stop without frame loss). 

cake/eat it

*59 if you're still running iOS 5.0.1

I am working on a project where we will be using iPhones as cameras for capturing a scene. When recording we need to record @60fps and not 30fps (as natively supported). So I am working on an app to do this as the iPhone 4S hardware supports 720p@60fps (if you jailbreak your phone you can achieve this).

Does anybody know how to do this in Objective-C on iOS? Today I saw an app out there (slopro) that can record 60fps on non jailbroken phones. Any advice or tips is much appreciated.

Capture 60fps in iPhone app

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在做一个项目，我们将使用iPhones作为捕捉场景的相机。录制时，我们需要录制@60fps，而不是30fps (本机支持)。因此，我正在开发一个应用程序来实现这一点，因为iPhone 4S硬件支持720p@60fps (如果你越狱你的手机就可以做到这一点)。有没有人知道如何在iOS的Objective-C中做到这一...

问在iPhone应用程序中捕获60fps
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