CODEWITHSUNDEEP
iosavfoundationavcapture
Zy Zhao
Zy Zhao

Reputation: 188

AVFoundation I use setActiveVideoMinFrameDuration didn't work

I use AVCaptureVideoDataOutput in my demo ,for take photos in loop (like scanner) without sound, so i set fps to low Level

[device setActiveVideoMinFrameDuration:CMTimeMake(1, 1)];
[device setActiveVideoMaxFrameDuration:CMTimeMake(1, 1)];

In my code, then do this

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
   fromConnection:(AVCaptureConnection *)connection
{
     NSLog(@"date");
}

for check is it work, I found it print 24 times in a second,not 1 times 1 second

PS: the device edition is iPhone 5C and iOS 8.12

Upvotes: 5

Views: 2753

Answers (2)

Mussa Charles
Mussa Charles

Reputation: 4452

SWIFT

For those who are looking for an elegant Swifty solution, here is what I got from the latest official documentation

The following code example illustrates how to select an iOS device’s highest possible frame rate:

func configureCameraForHighestFrameRate(device: AVCaptureDevice) {

 var bestFormat: AVCaptureDevice.Format?
 var bestFrameRateRange: AVFrameRateRange?

 for format in device.formats {
     for range in format.videoSupportedFrameRateRanges {
         if range.maxFrameRate > bestFrameRateRange?.maxFrameRate ?? 0 {
             bestFormat = format
             bestFrameRateRange = range
         }
     }
 }

 if let bestFormat = bestFormat, 
    let bestFrameRateRange = bestFrameRateRange {
     do {
         try device.lockForConfiguration()

         // Set the device's active format.
         device.activeFormat = bestFormat

         // Set the device's min/max frame duration.
         let duration = bestFrameRateRange.minFrameDuration
         device.activeVideoMinFrameDuration = duration
         device.activeVideoMaxFrameDuration = duration

         device.unlockForConfiguration()
     } catch {
         // Handle error.
     }
 }
}

Reference: Apple Official Documentation

Upvotes: 0

一有新人
一有新人

Reputation: 326

I just met the same problem.You should take a look at the function explanation about setActiveVideoMinFrameDuration or setActiveVideoMaxFrameDuration. Apple says:

On iOS, the receiver's activeVideoMinFrameDuration resets to its default value under the following conditions:
- The receiver's activeFormat changes
- The receiver's AVCaptureDeviceInput's session's sessionPreset changes
- The receiver's AVCaptureDeviceInput is added to a session

So, you should call setActiveVideoMinFrameDuration and setActiveVideoMaxFrameDuration after changing activeFormat,sessionPreset and AVCaptureSession's addInput.

Upvotes: 21

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