iOS 用前置摄像头闪光灯的新值覆盖 EXIF 闪光灯 属性
iOS overwrite EXIF flash property with new value for front camera flash
我正在尝试更改 Exif 词典的 kCGImagePropertyExifFlash 属性。我的应用程序提供前置闪光灯模式，因此我正在尝试更改此 Exif 值。当我使用 ALAssetsLibrary 的 writeImageDataToSavedPhotosAlbum 方法保存 newImageData 时，无论我做什么，它都会删除我设置的值。
如果能提供任何帮助，我将不胜感激。
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:
[self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo]
completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{
if (imageSampleBuffer && !error)
{
CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);
NSDictionary *metadata = [NSDictionary dictionaryWithDictionary:(__bridge NSDictionary *)metadataDict];
CFRelease(metadataDict);
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
if (metadata && imageData)
{
NSMutableDictionary *newMetaData = [NSMutableDictionary dictionaryWithDictionary:metadata];
NSMutableDictionary *exifMetadata = [NSMutableDictionary dictionaryWithDictionary:
[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary]];
if (self.isUsingFrontCamera && exifMetadata)
{
if (self.flashButton.flashMode == On)
{
[exifMetadata setObject:@"On, Fired" forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.flashButton.flashMode == Off)
{
[exifMetadata setObject:@"Off, did not fire" forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.frontFlashAutoDidFire)
{
[exifMetadata setObject:@"Auto, Fired" forKey:(NSString *)kCGImagePropertyExifFlash];
}
}
[newMetaData setObject:exifMetadata forKey:(NSString *)kCGImagePropertyExifDictionary];
NSData *newImageData = [self writeMetadataIntoImageData:imageData metadata:newMetaData];
[ALAssetsLibrary.new writeImageDataToSavedPhotosAlbum:newImageData metadata:nil completionBlock:nil];
}
}
}
- (NSData *)writeMetadataIntoImageData:(NSData *)imageData metadata:(NSDictionary *)metadata
{
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) imageData, NULL);
CFStringRef UTI = CGImageSourceGetType(source);
NSMutableData *data = [NSMutableData data];
CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)data, UTI, 1, NULL);
CGImageDestinationAddImageFromSource(destination, source, 0, (__bridge CFDictionaryRef) metadata);
CGImageDestinationFinalize(destination);
CFRelease(destination);
CFRelease(source);
return data;
}
我明白了；结果 kCGImagePropertyExifFlash 是 NSCFNumber，而不是 NSCFString，这是我的问题。我能够记录闪光灯模式的默认整数值：
- On, Fired 值为 9
- 关，没火是16的值
- 自动，不开火是24的值
- Auto, Fired 的值为 25
- 如果硬件设备不支持闪存，则值为 32
- 不确定任何其他可能的值，可能与闪光灯太热时无法使用有关。
代码：
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:
[self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo]
completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{
if (imageSampleBuffer && !error)
{
CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);
NSDictionary *metadata = [NSDictionary dictionaryWithDictionary:(__bridge NSDictionary *)metadataDict];
CFRelease(metadataDict);
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
if (metadata && imageData)
{
NSMutableDictionary *newMetaData = [NSMutableDictionary dictionaryWithDictionary:metadata];
NSMutableDictionary *exifMetadata = [NSMutableDictionary dictionaryWithDictionary:
[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary]];
if (self.isUsingFrontCamera && exifMetadata)
{
if (self.flashButton.flashMode == On)
{
[exifMetadata setObject:@(9) forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.flashButton.flashMode == Off)
{
[exifMetadata setObject:@(16) forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.flashButton.flashMode == Auto)
{
[exifMetadata setObject:@(24) forKey:(NSString *)kCGImagePropertyExifFlash];
if (self.frontFlashAutoDidFire)
{
[exifMetadata setObject:@(25) forKey:(NSString *)kCGImagePropertyExifFlash];
}
}
}
[newMetaData setObject:exifMetadata forKey:(NSString *)kCGImagePropertyExifDictionary];
[ALAssetsLibrary.new writeImageDataToSavedPhotosAlbum:imageData metadata:newMetaData completionBlock:nil];
}
}
}
当我 运行 在使用相机开发 iOS 应用程序时遇到同样的问题，我查找了一些典型的 EXIF 密钥及其标准 t运行 格式。
这是 EXIF flash 属性 描述：
IFD Exif
Code 37385 (hex 0x9209)
Name Flash
描述
Indicates the status of flash when the image was shot.
Bit 0 indicates the flash firing status, bits 1 and 2 indicate the flash return status, bits 3 and 4 indicate the flash mode, bit 5 indicates whether the flash function is present, and bit 6 indicates "red eye" mode.
Values for bit 0 indicating whether the flash fired.
0 = Flash did not fire
1 = Flash fired
Values for bits 1 and 2 indicating the status of returned light.
00 = No strobe return detection function
01 = reserved
10 = Strobe return light not detected
11 = Strobe return light detected
Values for bits 3 and 4 indicating the camera's flash mode.
00 = unknown
01 = Compulsory flash firing
10 = Compulsory flash suppression
11 = Auto mode
Values for bit 5 indicating the presence of a flash function.
0 = Flash function present
1 = No flash function
Values for bit 6 indicating the camera's red-eye mode.
0 = No red-eye reduction mode or unknown
1 = Red-eye reduction supported
Not all combinations make sense though. The specification defines these combined values:
hex 0000 = Flash did not fire
hex 0001 = Flash fired
hex 0005 = Strobe return light not detected
hex 0007 = Strobe return light detected
hex 0009 = Flash fired, compulsory flash mode
hex 000D = Flash fired, compulsory flash mode, return light not detected
hex 000F = Flash fired, compulsory flash mode, return light detected
hex 0010 = Flash did not fire, compulsory flash mode
hex 0018 = Flash did not fire, auto mode
hex 0019 = Flash fired, auto mode
hex 001D = Flash fired, auto mode, return light not detected
hex 001F = Flash fired, auto mode, return light detected
hex 0020 = No flash function
hex 0041 = Flash fired, red-eye reduction mode
hex 0045 = Flash fired, red-eye reduction mode, return light not detected
hex 0047 = Flash fired, red-eye reduction mode, return light detected
hex 0049 = Flash fired, compulsory flash mode, red-eye reduction mode
hex 004D = Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected
hex 004F = Flash fired, compulsory flash mode, red-eye reduction mode, return light detected
hex 0059 = Flash fired, auto mode, red-eye reduction mode
hex 005D = Flash fired, auto mode, return light not detected, red-eye reduction mode
hex 005F = Flash fired, auto mode, return light detected, red-eye reduction mode
使用十六进制到十进制的转换和 objective-C，这里有一个方法来 t运行slate 调用 :
给出的枚举
[[exifDictionary objectForKey : @"Flash"] integerValue]
进入NSString描述
-(NSString *) translateFlashEnumToNSString: (long) flash
{
switch (flash) {
case 0:
return @"Flash did not fire";
case 1:
return @"Flash did fire";
case 5:
return @"Strobe return light not detected";
case 7:
return @"Strobe return light detected";
case 9:
return @"Flash fired, compulsory flash mode";
case 13:
return @"Flash fired, compulsory flash mode, return light not detected";
case 15:
return @"Flash fired, compulsory flash mode, return light detected";
case 16:
return @"Flash did not fire, compulsory flash mode";
case 24:
return @"Flash did not fire, auto mode";
case 25:
return @"Flash fired, auto mode";
case 29:
return @"Flash fired, auto mode, return light not detected";
case 31:
return @"Flash fired, auto mode, return light detected";
case 32:
return @"No flash function";
case 65:
return @"Flash fired, red-eye reduction mode";
case 69:
return @"Flash fired, red-eye reduction mode, return light not detected";
case 71:
return @"Flash fired, red-eye reduction mode, return light detected";
case 73:
return @"Flash fired, compulsory flash mode, red-eye reduction mode";
case 77:
return @"Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected";
case 79:
return @"Flash fired, compulsory flash mode, red-eye reduction mode, return light detected";
case 89:
return @"Flash fired, auto mode, red-eye reduction mode";
case 93:
return @"Flash fired, auto mode, return light not detected, red-eye reduction mode";
case 95:
return @"Flash fired, auto mode, return light detected, red-eye reduction mode";
default:
return @"Flash mode unsupported";
}
}
调用方法：
NSLog(@"Flash EXIF : %@", [self translateFlashEnumToNSString: [[exifDictionary objectForKey:@"Flash"] integerValue]];
希望对您有所帮助。
对于其他 EXIF 密钥及其描述：http://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/flash.html
我正在尝试更改 Exif 词典的 kCGImagePropertyExifFlash 属性。我的应用程序提供前置闪光灯模式，因此我正在尝试更改此 Exif 值。当我使用 ALAssetsLibrary 的 writeImageDataToSavedPhotosAlbum 方法保存 newImageData 时，无论我做什么，它都会删除我设置的值。
如果能提供任何帮助，我将不胜感激。
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:
[self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo]
completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{
if (imageSampleBuffer && !error)
{
CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);
NSDictionary *metadata = [NSDictionary dictionaryWithDictionary:(__bridge NSDictionary *)metadataDict];
CFRelease(metadataDict);
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
if (metadata && imageData)
{
NSMutableDictionary *newMetaData = [NSMutableDictionary dictionaryWithDictionary:metadata];
NSMutableDictionary *exifMetadata = [NSMutableDictionary dictionaryWithDictionary:
[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary]];
if (self.isUsingFrontCamera && exifMetadata)
{
if (self.flashButton.flashMode == On)
{
[exifMetadata setObject:@"On, Fired" forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.flashButton.flashMode == Off)
{
[exifMetadata setObject:@"Off, did not fire" forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.frontFlashAutoDidFire)
{
[exifMetadata setObject:@"Auto, Fired" forKey:(NSString *)kCGImagePropertyExifFlash];
}
}
[newMetaData setObject:exifMetadata forKey:(NSString *)kCGImagePropertyExifDictionary];
NSData *newImageData = [self writeMetadataIntoImageData:imageData metadata:newMetaData];
[ALAssetsLibrary.new writeImageDataToSavedPhotosAlbum:newImageData metadata:nil completionBlock:nil];
}
}
}
- (NSData *)writeMetadataIntoImageData:(NSData *)imageData metadata:(NSDictionary *)metadata
{
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) imageData, NULL);
CFStringRef UTI = CGImageSourceGetType(source);
NSMutableData *data = [NSMutableData data];
CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)data, UTI, 1, NULL);
CGImageDestinationAddImageFromSource(destination, source, 0, (__bridge CFDictionaryRef) metadata);
CGImageDestinationFinalize(destination);
CFRelease(destination);
CFRelease(source);
return data;
}
我明白了；结果 kCGImagePropertyExifFlash 是 NSCFNumber，而不是 NSCFString，这是我的问题。我能够记录闪光灯模式的默认整数值：
- On, Fired 值为 9
- 关，没火是16的值
- 自动，不开火是24的值
- Auto, Fired 的值为 25
- 如果硬件设备不支持闪存，则值为 32
- 不确定任何其他可能的值，可能与闪光灯太热时无法使用有关。
代码：
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:
[self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo]
completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{
if (imageSampleBuffer && !error)
{
CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);
NSDictionary *metadata = [NSDictionary dictionaryWithDictionary:(__bridge NSDictionary *)metadataDict];
CFRelease(metadataDict);
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
if (metadata && imageData)
{
NSMutableDictionary *newMetaData = [NSMutableDictionary dictionaryWithDictionary:metadata];
NSMutableDictionary *exifMetadata = [NSMutableDictionary dictionaryWithDictionary:
[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary]];
if (self.isUsingFrontCamera && exifMetadata)
{
if (self.flashButton.flashMode == On)
{
[exifMetadata setObject:@(9) forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.flashButton.flashMode == Off)
{
[exifMetadata setObject:@(16) forKey:(NSString *)kCGImagePropertyExifFlash];
}
else if (self.flashButton.flashMode == Auto)
{
[exifMetadata setObject:@(24) forKey:(NSString *)kCGImagePropertyExifFlash];
if (self.frontFlashAutoDidFire)
{
[exifMetadata setObject:@(25) forKey:(NSString *)kCGImagePropertyExifFlash];
}
}
}
[newMetaData setObject:exifMetadata forKey:(NSString *)kCGImagePropertyExifDictionary];
[ALAssetsLibrary.new writeImageDataToSavedPhotosAlbum:imageData metadata:newMetaData completionBlock:nil];
}
}
}
当我 运行 在使用相机开发 iOS 应用程序时遇到同样的问题，我查找了一些典型的 EXIF 密钥及其标准 t运行 格式。
这是 EXIF flash 属性 描述：
IFD Exif
Code 37385 (hex 0x9209)
Name Flash
描述
Indicates the status of flash when the image was shot.
Bit 0 indicates the flash firing status, bits 1 and 2 indicate the flash return status, bits 3 and 4 indicate the flash mode, bit 5 indicates whether the flash function is present, and bit 6 indicates "red eye" mode.
Values for bit 0 indicating whether the flash fired.
0 = Flash did not fire
1 = Flash fired
Values for bits 1 and 2 indicating the status of returned light.
00 = No strobe return detection function
01 = reserved
10 = Strobe return light not detected
11 = Strobe return light detected
Values for bits 3 and 4 indicating the camera's flash mode.
00 = unknown
01 = Compulsory flash firing
10 = Compulsory flash suppression
11 = Auto mode
Values for bit 5 indicating the presence of a flash function.
0 = Flash function present
1 = No flash function
Values for bit 6 indicating the camera's red-eye mode.
0 = No red-eye reduction mode or unknown
1 = Red-eye reduction supported
Not all combinations make sense though. The specification defines these combined values:
hex 0000 = Flash did not fire
hex 0001 = Flash fired
hex 0005 = Strobe return light not detected
hex 0007 = Strobe return light detected
hex 0009 = Flash fired, compulsory flash mode
hex 000D = Flash fired, compulsory flash mode, return light not detected
hex 000F = Flash fired, compulsory flash mode, return light detected
hex 0010 = Flash did not fire, compulsory flash mode
hex 0018 = Flash did not fire, auto mode
hex 0019 = Flash fired, auto mode
hex 001D = Flash fired, auto mode, return light not detected
hex 001F = Flash fired, auto mode, return light detected
hex 0020 = No flash function
hex 0041 = Flash fired, red-eye reduction mode
hex 0045 = Flash fired, red-eye reduction mode, return light not detected
hex 0047 = Flash fired, red-eye reduction mode, return light detected
hex 0049 = Flash fired, compulsory flash mode, red-eye reduction mode
hex 004D = Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected
hex 004F = Flash fired, compulsory flash mode, red-eye reduction mode, return light detected
hex 0059 = Flash fired, auto mode, red-eye reduction mode
hex 005D = Flash fired, auto mode, return light not detected, red-eye reduction mode
hex 005F = Flash fired, auto mode, return light detected, red-eye reduction mode
使用十六进制到十进制的转换和 objective-C，这里有一个方法来 t运行slate 调用 :
给出的枚举[[exifDictionary objectForKey : @"Flash"] integerValue]
进入NSString描述
-(NSString *) translateFlashEnumToNSString: (long) flash
{
switch (flash) {
case 0:
return @"Flash did not fire";
case 1:
return @"Flash did fire";
case 5:
return @"Strobe return light not detected";
case 7:
return @"Strobe return light detected";
case 9:
return @"Flash fired, compulsory flash mode";
case 13:
return @"Flash fired, compulsory flash mode, return light not detected";
case 15:
return @"Flash fired, compulsory flash mode, return light detected";
case 16:
return @"Flash did not fire, compulsory flash mode";
case 24:
return @"Flash did not fire, auto mode";
case 25:
return @"Flash fired, auto mode";
case 29:
return @"Flash fired, auto mode, return light not detected";
case 31:
return @"Flash fired, auto mode, return light detected";
case 32:
return @"No flash function";
case 65:
return @"Flash fired, red-eye reduction mode";
case 69:
return @"Flash fired, red-eye reduction mode, return light not detected";
case 71:
return @"Flash fired, red-eye reduction mode, return light detected";
case 73:
return @"Flash fired, compulsory flash mode, red-eye reduction mode";
case 77:
return @"Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected";
case 79:
return @"Flash fired, compulsory flash mode, red-eye reduction mode, return light detected";
case 89:
return @"Flash fired, auto mode, red-eye reduction mode";
case 93:
return @"Flash fired, auto mode, return light not detected, red-eye reduction mode";
case 95:
return @"Flash fired, auto mode, return light detected, red-eye reduction mode";
default:
return @"Flash mode unsupported";
}
}
调用方法：
NSLog(@"Flash EXIF : %@", [self translateFlashEnumToNSString: [[exifDictionary objectForKey:@"Flash"] integerValue]];
希望对您有所帮助。 对于其他 EXIF 密钥及其描述：http://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/flash.html