我正在开发一个应用程序,需要尽可能多的fps捕获帧缓冲区.我已经弄清楚如何强制
iphone以60 fps捕获
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
方法被称为只有15次,这意味着iPhone降级捕获输出到15 fps.
有没有人面临这样的问题？是否有可能增加捕获帧速率？
更新我的代码：
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];
if (cameraInput == nil) {
NSLog(@"Error to create camera capture:%@",error);
}
// Set the output
AVCaptureVideoDataOutput* videoOutput = [[AVCaptureVideoDataOutput alloc] init];
// create a queue to run the capture on
dispatch_queue_t captureQueue=dispatch_queue_create("captureQueue",NULL);
// setup our delegate
[videoOutput setSampleBufferDelegate:self queue:captureQueue];
// configure the pixel format
videoOutput.videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA],(id)kCVPixelBufferPixelFormatTypeKey,nil];
// Add the input and output
[captureSession addInput:cameraInput];
[captureSession addOutput:videoOutput];
我在这里采用了configureCameraForHighestFrameRate方法https://developer.apple.com/library/mac/documentation/AVFoundation/Reference/AVCaptureDevice_Class/Reference/Reference.html
解决方法
我在iPhone 5上获得了60 fps的采样率,在iPhone 5上采用了120 fps,无论是在捕获输出中进行实时运动检测还是使用AVAssetWriter将帧保存到视频中.
您必须将AVCaptureSession设置为支持60 fps的格式：
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];
}
如果您想使用AVAssetWriter写入一个文件,另外两个评论.不要使用pixelAdaptor,只需要添加样品
[videoWriterInput appendSampleBuffer:sampleBuffer]
其次,当设置assetwriter使用
[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings
sourceFormatHint:formatDescription];
sourceFormatHint在写入速度方面有所不同.
