80 lines
2.6 KiB
Objective-C
80 lines
2.6 KiB
Objective-C
//
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// SCCameraSettingUtils.m
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// Snapchat
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//
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// Created by Pinlin Chen on 12/09/2017.
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//
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#import "SCCameraSettingUtils.h"
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#import <SCFoundation/SCLog.h>
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#import <ImageIO/CGImageProperties.h>
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NSNumber *retrieveExposureTimeFromEXIFAttachments(CFDictionaryRef exifAttachments)
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{
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if (!exifAttachments) {
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return nil;
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}
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id value = CFDictionaryGetValue(exifAttachments, kCGImagePropertyExifExposureTime);
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// Fetching exposure time from the sample buffer
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if ([value isKindOfClass:[NSNumber class]]) {
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return (NSNumber *)value;
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}
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return nil;
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}
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NSNumber *retrieveBrightnessFromEXIFAttachments(CFDictionaryRef exifAttachments)
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{
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if (!exifAttachments) {
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return nil;
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}
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id value = CFDictionaryGetValue(exifAttachments, kCGImagePropertyExifBrightnessValue);
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if ([value isKindOfClass:[NSNumber class]]) {
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return (NSNumber *)value;
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}
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return nil;
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}
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NSNumber *retrieveISOSpeedRatingFromEXIFAttachments(CFDictionaryRef exifAttachments)
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{
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if (!exifAttachments) {
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return nil;
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}
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NSArray *ISOSpeedRatings = CFDictionaryGetValue(exifAttachments, kCGImagePropertyExifISOSpeedRatings);
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if ([ISOSpeedRatings respondsToSelector:@selector(count)] &&
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[ISOSpeedRatings respondsToSelector:@selector(firstObject)] && ISOSpeedRatings.count > 0) {
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id value = [ISOSpeedRatings firstObject];
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if ([value isKindOfClass:[NSNumber class]]) {
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return (NSNumber *)value;
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}
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}
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return nil;
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}
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void retrieveSampleBufferMetadata(CMSampleBufferRef sampleBuffer, SampleBufferMetadata *metadata)
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{
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CFDictionaryRef exifAttachments = CMGetAttachment(sampleBuffer, kCGImagePropertyExifDictionary, NULL);
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if (exifAttachments == nil) {
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SCLogCoreCameraWarning(@"SampleBuffer exifAttachment is nil");
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}
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// Fetching exposure time from the sample buffer
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NSNumber *currentExposureTimeNum = retrieveExposureTimeFromEXIFAttachments(exifAttachments);
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if (currentExposureTimeNum) {
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metadata->exposureTime = [currentExposureTimeNum floatValue];
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}
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NSNumber *currentISOSpeedRatingNum = retrieveISOSpeedRatingFromEXIFAttachments(exifAttachments);
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if (currentISOSpeedRatingNum) {
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metadata->isoSpeedRating = (int)[currentISOSpeedRatingNum integerValue];
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}
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NSNumber *currentBrightnessNum = retrieveBrightnessFromEXIFAttachments(exifAttachments);
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if (currentBrightnessNum) {
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float currentBrightness = [currentBrightnessNum floatValue];
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if (isfinite(currentBrightness)) {
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metadata->brightness = currentBrightness;
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} else {
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metadata->brightness = 0;
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}
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}
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}
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