AVCapture capturing and getting framebuffer at 60 fps in iOS 7

Question

I'm developping an app which requires capturing framebuffer at as much fps as possible. I've already figured out how to force iphone to capture at 60 fps but ``` - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection ``` method is being called only 15 times a second, which means that iPhone downgrades capture output to 15 fps. Has anybody faced such problem? Is there any possibility to increase capturing frame rate? Update my code: ``` camera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; if([camera isTorchModeSupported:AVCaptureTorchModeOn]) { [camera lockForConfiguration:nil]; camera.torchMode=AVCaptureTorchModeOn; [camera unlockForConfiguration]; } [self configureCameraForHighestFrameRate:camera]; // Create a AVCaptureInput with the camera device NSError *error=nil; AVCaptureInput* cameraInput = [[AVCaptureDeviceInput alloc] initWithDevice:camera error:&error]; i…

Accepted Answer

I am getting samples at 60 fps on the iPhone 5 and 120 fps on the iPhone 5s, both when doing real time motion detection in captureOutput and when saving the frames to a video using AVAssetWriter.

You have to set thew AVCaptureSession to a format that supports 60 fps:

```
AVsession = [[AVCaptureSession alloc] init];

AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *capInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
if (capInput) [AVsession addInput:capInput];

for(AVCaptureDeviceFormat *vFormat in [videoDevice formats] ) 
{
    CMFormatDescriptionRef description= vFormat.formatDescription;
    float maxrate=((AVFrameRateRange*)[vFormat.videoSupportedFrameRateRanges objectAtIndex:0]).maxFrameRate;

if(maxrate>59 && CMFormatDescriptionGetMediaSubType(description)==kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
    {
        if ( YES == [videoDevice lockForConfiguration:NULL] ) 
        {
           videoDevice.activeFormat = vFormat;
           [videoDevice setActiveVideoMinFrameDuration:CMTimeMake(10,600)];
           [videoDevice setActiveVideoMaxFrameDuration:CMTimeMake(10,600)];
           [videoDevice unlockForConfiguration];
           NSLog(@"formats  %@ %@ %@",vFormat.mediaType,vFormat.formatDescription,vFormat.videoSupportedFrameRateRanges);
        }
     }
}

prevLayer = [AVCaptureVideoPreviewLayer layerWithSession: AVsession];
prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer: prevLayer];

AVCaptureVideoDataOutput *videoOut = [[AVCaptureVideoDataOutput alloc] init];
dispatch_queue_t videoQueue = dispatch_queue_create("videoQueue", NULL);
[videoOut setSampleBufferDelegate:self queue:videoQueue];

videoOut.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey: @(kCVPixelFormatType_32BGRA)};
videoOut.alwaysDiscardsLateVideoFrames=YES;

if (videoOut)
{
    [AVsession addOutput:videoOut];
    videoConnection = [videoOut connectionWithMediaType:AVMediaTypeVideo];
}
```

Two other comment if you want to write to a file using AVAssetWriter. Don't use the pixelAdaptor, just ad the samples with

```
[videoWriterInput appendSampleBuffer:sampleBuffer]
```

Secondly when setting up the assetwriter use

```
[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo
                                   outputSettings:videoSettings 
                                 sourceFormatHint:formatDescription];
```

The sourceFormatHint makes a difference in writing speed.

AVCapture capturing and getting framebuffer at 60 fps in iOS 7

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