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/*
* Copyright 2017 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#import "AVCaptureSession+DevicePosition.h"
BOOL CFStringContainsString(CFStringRef theString, CFStringRef stringToFind) {
return CFStringFindWithOptions(theString,
stringToFind,
CFRangeMake(0, CFStringGetLength(theString)),
kCFCompareCaseInsensitive,
nil);
}
@implementation AVCaptureSession (DevicePosition)
+ (AVCaptureDevicePosition)devicePositionForSampleBuffer:(CMSampleBufferRef)sampleBuffer {
// Check the image's EXIF for the camera the image came from.
AVCaptureDevicePosition cameraPosition = AVCaptureDevicePositionUnspecified;
CFDictionaryRef attachments = CMCopyDictionaryOfAttachments(
kCFAllocatorDefault, sampleBuffer, kCMAttachmentMode_ShouldPropagate);
if (attachments) {
int size = CFDictionaryGetCount(attachments);
if (size > 0) {
CFDictionaryRef cfExifDictVal = nil;
if (CFDictionaryGetValueIfPresent(
attachments, (const void *)CFSTR("{Exif}"), (const void **)&cfExifDictVal)) {
CFStringRef cfLensModelStrVal;
if (CFDictionaryGetValueIfPresent(cfExifDictVal,
(const void *)CFSTR("LensModel"),
(const void **)&cfLensModelStrVal)) {
if (CFStringContainsString(cfLensModelStrVal, CFSTR("front"))) {
cameraPosition = AVCaptureDevicePositionFront;
} else if (CFStringContainsString(cfLensModelStrVal, CFSTR("back"))) {
cameraPosition = AVCaptureDevicePositionBack;
}
}
}
}
CFRelease(attachments);
}
return cameraPosition;
}
@end