问题
Whats the best method to find the image resolution going to be captured using setting AVCaptureSessionPresetPhoto.
I am trying to find the resolution before capturing the image.
回答1:
With the function below, you can programmatically get the resolution from activeFormat before capture begins, though not before adding inputs and outputs:
https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/AVCaptureDevice_Class/index.html#//apple_ref/occ/instp/AVCaptureDevice/activeFormat
private func getCaptureResolution() -> CGSize {
// Define default resolution
var resolution = CGSize(width: 0, height: 0)
// Get cur video device
let curVideoDevice = useBackCamera ? backCameraDevice : frontCameraDevice
// Set if video portrait orientation
let portraitOrientation = orientation == .Portrait || orientation == .PortraitUpsideDown
// Get video dimensions
if let formatDescription = curVideoDevice?.activeFormat.formatDescription {
let dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription)
resolution = CGSize(width: CGFloat(dimensions.width), height: CGFloat(dimensions.height))
if portraitOrientation {
resolution = CGSize(width: resolution.height, height: resolution.width)
}
}
// Return resolution
return resolution
}
回答2:
Here is the a table of all tested camera sessionPreset`s on devices, that support iOS 9
+-----------------------+--------------+---------------------------------+---------------+
| Device | Camera | AVCaptureSessionPreset | Resolution |
+-----------------------+--------------+---------------------------------+---------------+
| iPhone 4S | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 640x480 |
| | | AVCaptureSessionPresetHigh | 640x480 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | not supported |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 3264x2448 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPhone 5/5C/5S/6/6+ | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 1280x960 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 3264x2448 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPhone 6S/6S | | | |
| | FRONT camera | | |
| | | AVCaptureSessionPresetPhoto | 1280x960 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK camera | | |
| | | AVCaptureSessionPresetPhoto | 4032x3024 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPad 2 | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 640x480 |
| | | AVCaptureSessionPresetHigh | 640x480 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | not supported |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 960x720 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
+-----------------------+--------------+---------------------------------+---------------+
| iPad 3 | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 640x480 |
| | | AVCaptureSessionPresetHigh | 640x480 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | not supported |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 2592x1936 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPad 4/Air | | | |
| iPad Mini 1/2/3 | | | |
| iPod 5G | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 1280x960 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 2592x1936 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPad Air 2 | | | |
| iPad Mini 4 | | | |
| iPad Pro | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 1280x960 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 3264x2448 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPod Touch 5 | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 1280x960 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 2592x1936 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
| iPod Touch 6 | | | |
| | FRONT | | |
| | | AVCaptureSessionPresetPhoto | 1280x960 |
| | | AVCaptureSessionPresetHigh | 1280x720 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | not supported |
| | BACK | | |
| | | AVCaptureSessionPresetPhoto | 3264x2448 |
| | | AVCaptureSessionPresetHigh | 1920x1080 |
| | | AVCaptureSessionPresetMedium | 480x360 |
| | | AVCaptureSessionPresetLow | 192x144 |
| | | AVCaptureSessionPreset640x480 | 640x480 |
| | | AVCaptureSessionPreset1280x720 | 1280x720 |
| | | AVCaptureSessionPreset1920x1080 | 1920x1080 |
+-----------------------+--------------+---------------------------------+---------------+
CODE
+ (NSDictionary*) cameraResolutions {
NSString* deviceModel = [self deviceModel];
// iPhone 4S
if ([deviceModel isEqualToString:@"iPhone4,1"]) {
NSString* lFrontCam = @"640x480,480x360,192x144";
NSString* lBackCam = @"3264x2448,1920x1080,1280x720,640x480,480x360,192x144";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
// iPhone 5/5C/5S/6/6+/iPod 6
else if ([deviceModel isEqualToString:@"iPhone5,1"]
|| [deviceModel isEqualToString:@"iPhone5,2"]
|| [deviceModel isEqualToString:@"iPhone5,3"]
|| [deviceModel isEqualToString:@"iPhone5,4"]
|| [deviceModel isEqualToString:@"iPhone6,1"]
|| [deviceModel isEqualToString:@"iPhone6,2"]
|| [deviceModel isEqualToString:@"iPhone7,1"]
|| [deviceModel isEqualToString:@"iPhone7,2"]
|| [deviceModel isEqualToString:@"iPod7,1"]) {
NSString* lFrontCam = @"1280x960,1280x720,640x480,480x360,192x144";
NSString* lBackCam = @"3264x2448,1920x1080,1280x720,640x480,480x360,192x144";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
// iPhone 6S/6S+
else if ([deviceModel isEqualToString:@"iPhone8,1"]
|| [deviceModel isEqualToString:@"iPhone8,2"]) {
NSString* lFrontCam = @"1280x960,1280x720,640x480,480x360,192x144";
NSString* lBackCam = @"4032x3024,1920x1080,1280x720,640x480,480x360,192x144";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
// iPad 2
else if ([deviceModel isEqualToString:@"iPad2,1"]
|| [deviceModel isEqualToString:@"iPad2,2"]
|| [deviceModel isEqualToString:@"iPad2,3"]
|| [deviceModel isEqualToString:@"iPad2,4"]) {
NSString* lFrontCam = @"640x480,480x360,192x144";
NSString* lBackCam = @"1280x720,960x720,480x360,192x144,640x480";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
// iPad 3
else if ([deviceModel isEqualToString:@"iPad3,1"]
|| [deviceModel isEqualToString:@"iPad3,2"]
|| [deviceModel isEqualToString:@"iPad3,3"]) {
NSString* lFrontCam = @"640x480,480x360,192x144";
NSString* lBackCam = @"2592x1936,1920x1080,1280x720,640x480,480x360,192x144";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
// iPad 4/Air/Mini/Mini 2/Mini 3/iPod 5G
else if ([deviceModel isEqualToString:@"iPad3,4"]
|| [deviceModel isEqualToString:@"iPad3,5"]
|| [deviceModel isEqualToString:@"iPad3,6"]
|| [deviceModel isEqualToString:@"iPad4,1"]
|| [deviceModel isEqualToString:@"iPad4,2"]
|| [deviceModel isEqualToString:@"iPad4,3"]
|| [deviceModel isEqualToString:@"iPad4,4"]
|| [deviceModel isEqualToString:@"iPad4,5"]
|| [deviceModel isEqualToString:@"iPad4,6"]
|| [deviceModel isEqualToString:@"iPad4,7"]
|| [deviceModel isEqualToString:@"iPad4,8"]
|| [deviceModel isEqualToString:@"iPod5,1"]) {
NSString* lFrontCam = @"1280x960,1280x720,640x480,480x360,192x144";
NSString* lBackCam = @"2592x1936,1920x1080,1280x720,640x480,480x360,192x144";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
// iPad Air 2/Mini 4/Pro
else if ([deviceModel isEqualToString:@"iPad5,3"]
|| [deviceModel isEqualToString:@"iPad5,4"]) {
NSString* lFrontCam = @"1280x960,1280x720,640x480,480x360,192x144";
NSString* lBackCam = @"3264x2448,1920x1080,1280x720,640x480,480x360,192x144";
NSDictionary* lCamResolutions = @{@"front":lFrontCam,
@"back":lBackCam};
return lCamResolutions;
}
return nil;
}
回答3:
There's probably no way to directly get the camera resolution programmatically before capturing an image.
Apple provides a table for various devices and presets:
Capturing Still Images
回答4:
Can be done in this way:
/* Callback that is called when you activate the capture session. */
- (void) avCaptureInputPortFormatDescriptionDidChangeNotification:(NSNotification *)notification {
CMFormatDescriptionRef formatDescription = nil;
NSArray *ports = [deviceInput ports];
AVCaptureInputPort *usePort = nil;
for (AVCaptureInputPort *port in ports) {
if (usePort == nil || [port.mediaType isEqualToString:AVMediaTypeVideo]) {
usePort = port;
break;
}
}
if (usePort != nil)
formatDescription = usePort.formatDescription;
if (formatDescription != nil) {
/*------------>>>>>>> THIS IS YOUR RESOLUTION */
CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription);
self.frameSize = CGSizeMake(dimensions.width, dimensions.height);
[[NSNotificationCenter defaultCenter] removeObserver:self];
NSLog(@"Capturing with %dx%d", (int)self.frameSize.width, (int)self.frameSize.height);
} else {
NSLog(@"Failed to detect resolution, using default one.");
self.frameSize = CGSizeMake(640.0f, 480.0f);
}
}
- (id) init {
if ((self = [super init])) {
/* Default framesize. */
self.frameSize = CGSizeMake(640.0f, 480.0f);
AVCaptureSession *capSession = [[AVCaptureSession alloc] init];
/* -------->>>>>>> REQUESTED RESOLUTION, CAN BE SOMTHING ELSE */
[capSession setSessionPreset:AVCaptureSessionPresetHigh];
// if (([modelName rangeOfString:@"iPhone 5"].length != 0) || ([modelName rangeOfString:@"iPhone 6"].length != 0)) {
// [capSession setSessionPreset:AVCaptureSessionPresetHigh];
// } else {
// [capSession setSessionPreset:AVCaptureSessionPreset640x480];
// }
//
self.captureSession = capSession;
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(avCaptureInputPortFormatDescriptionDidChangeNotification:)
name:AVCaptureInputPortFormatDescriptionDidChangeNotification object:nil];
}
return self;
}
- (void) dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
if (self.captureSession.isRunning)
[self.captureSession stopRunning];
self.captureSession = nil;
}
- (void) addRawViewOutput
{
/* We setup the output */
AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init];
/* While a frame is processes in -captureOutput:didOutputSampleBuffer:fromConnection: delegate methods
no other frames are added in the queue.
If you don't want this behaviour set the property to NO */
captureOutput.alwaysDiscardsLateVideoFrames = YES;
/*We specify a minimum duration for each frame (play with this settings to avoid having too many frames waiting
in the queue because it can cause memory issues). It is similar to the inverse of the maximum framerate.
In this example we set a min frame duration of 1/10 seconds so a maximum framerate of 10fps. We say that
we are not able to process more than 10 frames per second.*/
//captureOutput.minFrameDuration = CMTimeMake(1, 10);
/*We create a serial queue to handle the processing of our frames*/
dispatch_queue_t queue;
queue = dispatch_queue_create("com.YourApp.cameraQueue", NULL);
[captureOutput setSampleBufferDelegate:self queue:queue];
// dispatch_release(queue);
// Set the video output to store frame in BGRA (It is supposed to be faster)
NSString *key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber *value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
[captureOutput setVideoSettings:videoSettings];
// Register an output
[self.captureSession addOutput:captureOutput];
}
- (bool) startWithDevicePosition:(AVCaptureDevicePosition)devicePosition
{
AVCaptureDevice *videoDevice = [self cameraWithPosition:devicePosition];
if (!videoDevice)
return FALSE;
NSError *error;
AVCaptureDeviceInput *videoIn = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
self.deviceInput = videoIn;
if (!error)
{
if ([[self captureSession] canAddInput:videoIn])
{
[[self captureSession] addInput:videoIn];
}
else
{
NSLog(@"Couldn't add video input");
return FALSE;
}
}
else
{
NSLog(@"Couldn't create video input");
return FALSE;
}
[self addRawViewOutput];
[self resume];
return TRUE;
}
-(void) pause
{
self.paused = YES;
if (self.captureSession.isRunning)
[captureSession stopRunning];
}
-(void) resume
{
if (!self.captureSession.isRunning)
[captureSession startRunning];
self.paused = NO;
}
#pragma mark -
#pragma mark AVCaptureSession delegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection
{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
/* Lock the image buffer */
CVPixelBufferLockBaseAddress(imageBuffer,0);
/* Get information about the image */
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
size_t stride = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t size = CVPixelBufferGetDataSize(imageBuffer);
BGRAVideoFrame frame = {(int)width, (int)height, (int)stride, (int)size, baseAddress};
[delegate frameReady:frame];
/* We unlock the image buffer */
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}
回答5:
Try this code for get maximum Image resolution for device cameras:
- (CMVideoDimensions) getCameraMaxStillImageResolution:(AVCaptureDevicePosition) cameraPosition {
CMVideoDimensions max_resolution;
max_resolution.width = 0;
max_resolution.height = 0;
AVCaptureDevice *captureDevice = nil;
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *device in devices) {
if ([device position] == cameraPosition) {
captureDevice = device;
break;
}
}
if (captureDevice == nil) {
return max_resolution;
}
NSArray* availFormats=captureDevice.formats;
for (AVCaptureDeviceFormat* format in availFormats) {
CMVideoDimensions resolution = format.highResolutionStillImageDimensions;
int w = resolution.width;
int h = resolution.height;
if ((w * h) > (max_resolution.width * max_resolution.height)) {
max_resolution.width = w;
max_resolution.height = h;
}
}
return max_resolution;
}
- (void) printCamerasInfo {
CMVideoDimensions res;
res = [self getCameraMaxStillImageResolution:AVCaptureDevicePositionBack];
NSLog(@" Back Camera max Image resolution: %d x %d", res.width, res.height);
res = [self getCameraMaxStillImageResolution:AVCaptureDevicePositionFront];
NSLog(@" Front Camera max Image resolution: %d x %d", res.width, res.height);
}
来源：https://stackoverflow.com/questions/19422322/method-to-find-devices-camera-resolution-ios