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drewnoakes / metadata-extractor

Extracts Exif, IPTC, XMP, ICC and other metadata from image, video and audio files
Apache License 2.0
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Canon CR3 files reporting incorrect Focus Distance values #605

Open johnbaro opened 1 year ago

johnbaro commented 1 year ago

Per this sample image, the values below show as zero, whereas the correct values are reported by exiftool

metadata-extractor

[Canon Makernote] Focus Distance Upper - 0
[Canon Makernote] Focus Distance Lower - 0

exiftool

Focus Distance Upper            : 0.95 m
Focus Distance Lower            : 0.94 m

I'd be happy to help out on this given some guidance as to where issue is occurring.

drewnoakes commented 1 year ago

Those tags are defined in:

https://github.com/drewnoakes/metadata-extractor/blob/5754a0d33659e6b1e9d8f35cf24bc03e0fbaf1b6/Source/com/drew/metadata/exif/makernotes/CanonMakernoteDirectory.java#L348-L349

Certain Canon makernote values have logic to present their values in:

https://github.com/drewnoakes/metadata-extractor/blob/5754a0d33659e6b1e9d8f35cf24bc03e0fbaf1b6/Source/com/drew/metadata/exif/makernotes/CanonMakernoteDescriptor.java#L47

It looks like there's no specific handling for those tags, so one idea would be to add them.

However I'm unclear whey we're showing a zero here. The first step would be to run in a debugger and identify what value was read from the backing data. It's possible the code that reads data into the CanonMakernoteDirectory is faulty here.

johnbaro commented 1 year ago

Thanks @drewnoakes, I did run a debugger through and saw they were zero but didn't get further than that due to time.
I'll do a deeper dive shortly.