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actigraph / GT3X-File-Format

Documentation of the ActiGraph .gt3x file format
MIT License
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Is file format of .GT3X (upper case) the same as .gt3x (lower case)? #21

Open vincentvanhees opened 2 years ago

vincentvanhees commented 2 years ago

I recently learnt that the ActiGraph Center Point service generates .GT3X files, with the extension in upper case. When I replace it by lower case extension I am able to process the file as if it was a .gt3x file.

Can you confirm that .gt3x and .GT3X are the same file format? Or are there subtle differences in the format that users need to be aware of?

joe-nguyen-actigraph commented 2 years ago

The gt3x or GT3X extension doesn't really give much to go on as far as differences in the files. Looking at the contents inside is the best way to tell the difference. For example, the devices used in the NHANES study has an eeprom.bin, alongside log.bin and epoch.bin. The newer devices such as wGT3X-BT, GT9X, and CPIW don't have an eeprom.bin. The GT3X/gt3x is just a fancy way of saying it's a zip file.

vincentvanhees commented 2 years ago

Thanks for clarifying. In that case my question becomes:

CPIW files with serial numbers starting with CPW are not listed in the README. Do they have a unique format or is their format identical to for example the serial numbers starting with CLE or TAS?

joe-nguyen-actigraph commented 2 years ago

CPW serial prefixes are different. The files are exported with agdc extension. Still just a zip file with a log.bin inside. The records are somewhat different. The log.bin has some new record types with the record numbers below in decimal:

Also, some of the previous record numbers have been re-purposed. Amongst other differences, the raw data isn't calibrated on the device and is stored non-calibrated. Thus, the agdc file has calibration constants included to be applied post data collection. As far as I know, I don't believe we've put out any public facing info about CPW serial prefixes.

vincentvanhees commented 2 years ago

Thanks, the only reason I am asking is because apparently your customers are able to download those files and then one of them asked me whether R package read.gt3x can process these files.