Canon CR3 files reporting incorrect Focus Distance values

[johnbaro]

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]

Those tags are defined in:

metadata-extractor/Source/com/drew/metadata/exif/makernotes/CanonMakernoteDirectory.java

Lines 348 to 349 in 5754a0d

	public static final int TAG_FOCUS_DISTANCE_UPPER = OFFSET + 19;
	public static final int TAG_FOCUS_DISTANCE_LOWER = OFFSET + 20;

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

metadata-extractor/Source/com/drew/metadata/exif/makernotes/CanonMakernoteDescriptor.java

Line 47 in 5754a0d

public String getDescription(int tagType)

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]

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.