Cannot read metadata from HEIC files

[jblum66]

Hi,

The software digikam (v8.7.0) uses Exiv2 internally to decode the metadata. Unfortunately, Exiv2 seems to have a problem with my HEIF photos. This prevents Digikam from retrieving GPS information from the image metadata. According to a digikam developer, it generates an exception:

digikam.metaengine: Exiv2 ( 3 ) :  Directory Image: Next pointer is out of bounds; ignored.
digikam.metaengine: Exiv2 ( 3 ) :  Upper boundary of data for directory Photo, entry 0x927c is out of bounds: Offset = 0x0000030a, size = 65564, exceeds buffer size by 815 Bytes; truncating the entry
digikam.metaengine: Exiv2 ( 3 ) :  Offset of directory Photo, entry 0xa404 is out of bounds: Offset = 0x00010326; truncating the entry
digikam.metaengine: Exiv2 ( 3 ) :  Directory Image, entry 0x8825 Sub-IFD pointer 0 is out of bounds; ignoring it.

It's a photo taken by a Poco F7 Ultra in HEIF/HEIC format.

This exception comes from the EXV container created by ExifTool 13.40.
Exiv2 wouldn't find any metadata directly in the image.

digikam bug link: https://bugs.kde.org/show_bug.cgi?id=511467

I tried myself Exiv2 for the first time. I'm using the EXE binary file for Windows:

exiv2.exe -v -Qd  H:\xxx\IMG_20251011_222520.HEIC

File 1/1: H:\xxx\IMG_20251011_222520.HEIC
File name       : H:\xxx\IMG_20251011_222520.HEIC
File size       : 936139 Bytes
MIME type       : image/heic
Image size      : 4096 x 3072
H:\xxx\IMG_20251011_222520.HEIC: No Exif data found in the file

IMG_20251011_222520.zip

[jblum66]

Is it relative to #2162 ?

[clanmills]

Good find, @jblum66 Very nice cat and decent bottle of wine. macOS Preview.app doesn't report the metadata in this file either!

I don't think this is #2162 because the fix for that was in exiv2 v0.27.7 with which I've reproduced your issue.

I have located the Exif metadata using brute force. I looked for the TIFF marker "||*\0" and used dd to extract it. Exif metadata is a TIFF file embedded your file. It's at offset 764426

659 rmills@rmillsm4:~/Downloads $ dmpf  IMG_20251011_222520.HEIC | grep 'II\*'
 0xbaa00   764416: ..,.Exif__II*_.___._..._.___.___  ->  ff e1 2c 99 45 78 69 66 00 00 49 49 2a 00 08 00 00 00 10 00 99 99 02 00 84 00 00 00 ce 00 00 00
661 rmills@rmillsm4:~/Downloads $ dd bs=1 skip=764426 count=1000000 if=IMG_20251011_222520.HEIC of=magic.tiff 2>/dev/null
661 rmills@rmillsm4:~/Downloads $ exiftool magic.tiff  | grep GPS
GPS Latitude Ref                : North
GPS Speed                       : 0
GPS Altitude Ref                : Above Sea Level
GPS Processing Method           : network
GPS Speed Ref                   : km/h
GPS Longitude Ref               : East
GPS Time Stamp                  : 20:25:09
GPS Date Stamp                  : 2025:10:11
GPS Altitude                    : 221.2 m Above Sea Level
GPS Date/Time                   : 2025:10:11 20:25:09Z
GPS Latitude                    : 48 deg 47' 19.11" N
GPS Longitude                   : 2 deg 2' 20.46" E
GPS Position                    : 48 deg 47' 19.11" N, 2 deg 2' 20.46" E
662 rmills@rmillsm4:~/Downloads $ exiftool magic.tiff  | grep GPS
637 rmills@rmillsm4:~/Downloads $ 

It's here in infe record [50]

692 rmills@rmillsm4:~/Downloads $ tvisitor -pRU IMG_20251011_222520.HEIC | grep -i exif
        1029 |       21 | infe |   50 | .__._2__Exif_ 2 0 0 1 0 50 0 0 69 120 105 102 0
693 rmills@rmillsm4:~/Downloads $

There's no doubt about this. I ran exiftool -v5 IMG_20251011_222520.HEIC and that's where Phil Harvey found the Exif data.

Although I worked on this code, my C++/Xcode/debugging skills are rusty and insufficient to dig deeper into this matter.

[jblum66]

They publish a workaround in my Digikam bug https://bugs.kde.org/show_bug.cgi?id=511467 to bypass the problem in MakerNotes, and it works!