ios - What`s the compression ratio of NSData from AVCaptureStillImageOutput? -


use jpegstillimagensdatarepresentation: method can nsdata avcapurestillimageoutput, can write data file.

nsdata * imagedata = [avcapturestillimageoutput jpegstillimagensdatarepresentation:imagesamplebuffer];

just imagesamplebuffer turn nsdata. can compression radio in method, or there index measure this?

just uiimagejpegrepresentation(uiimage* image, 1.0) this, has 1.0 measure compression radio image.

you can control compression (0-1) used avcapturestillimageoutput.

[stillimageoutput setoutputsettings:@{avvideocodeckey : avvideocodecjpeg, avvideoqualitykey:@1.0}];

see avcaptureoutput.h , avvideosettings.h: avvideoqualitykey supported on ios 6.0 , later , may used when avvideocodeckey set avvideocodecjpeg. avvideoqualitykey nsnumber (0.0-1.0, jpeg only)

you can verify key works looking @ size of data different values. default value don't think it's 1.0 because when set 1.0 size bumps bit , didn't setup tripod attempt take same pic....


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