gpr_tools -i GOPR0001.GPR -o GOPR0001.jpg -r 1:1

cashes with:

Could not decode input vc5 bitstream. Error number 20
gpr_tools: /home/zp/code/gpr/source/lib/gpr_sdk/private/gpr.cpp:1735: bool gpr_convert_gpr_to_rgb(const gpr_allocator*, GPR_RGB_RESOLUTION, int, gpr_buffer*, gpr_rgb_buffer*): Assertion `0' failed.
Aborted (core dumped)

Error number 20 is CODEC_ERROR_UNSUPPORTED_FORMAT

The problem is parameters->rgb_resolution == GPR_RGB_RESOLUTION_FULL case havn't been implemented here: https://github.com/gopro/gpr/blob/master/source/lib/vc5_decoder/decoder.c#L201