Metadata for Google Photos Date, GPS, Caption using ExifTool and FFMPEG

[Bob Rudolph]

I'm successfully uploading scanned older photos and generated video files containing metadata to Google Photos. Google Photos is recognizing the metadata and using it for presentation. I seem to be having metadata success for photo Date, GPS, Caption and for video Date, GPS, examples below. I'm looking for the necessary metadata to show Google Photos video Captions; I believe I have Google Photos photo Captions working well.

I'm hoping others who have also had success with metadata on Google Photos can share the tested metadata that has worked for them. I'm particularly looking for the metadata for video Captions that Google Photos will recognize and present.

Excellent would be for a smart person to start a reference/help doc on the ExifTool and FFMPEG websites on how to feed metadata to Google Photos. Maybe the docs are there and I just can't find them!

The following examples seem to be working for me using ExifTool, FFMPEG and Google Photos. But I'm just a hacker; I'm sure these examples can be improved, refined, optimized, corrected!

Photo Date, GPS, Caption on Google Photos
exiftool -q -overwrite_original -ExifIFD:DateTimeOriginal="19910402 18:00:00" -GPSLatitudeRef=N -GPSLatitude=28.419412 -GPSLongitudeRef=W -GPSLongitude=81.581168 -XMP-dc:Description="Walt Disney World Magic Kingdom on 04/02/1991" MyTestFile_WDW_MagicKingdom.jpg

Video Date, GPS on Google Photos
ffmpeg -i MyTestVideo.mp4 -map_metadata 0 -metadata location=28.419412-81.581168/ -metadata location-eng=28.419412-81.581168/ -c copy MyTestVideoOutput.mp4
exiftool -q -overwrite_original -CreateDate="19910402 18:00:00" -MediaCreateDate="19910402 18:00:00" MyTestVideoOutput.mp4

Looking for metadata for video Captions that Google Photos will recognize and present.