TABLE V.

Computational costs of all Models.

	Index	Methods	Num. of parameters	GFLOPs	Memory usage (bytes)
Previous	1	1D-VGG-16 [6] (PPG only)	1,626,403	2.36G	6,536,192
	2	1D-VGG-16 [6] (four channels)	1,626,691	2.38G	6,537,216
	3	2D DenseNet [8] (2D TFS)	221,303	19.33G	927,744
Ours (1D-Bi-GRU)	5	PPG only	110,696	0.75G	458,240
	4	HR only
	6	PPG + ACC	113,832	0.77G	470,528
	7	HR + ACC
	9	HR + magHR
	8	PPG + HR
	10	HR + magHR + ACC	117,008	0.83G	483,328
	11	PPG + HR + ACC
	12	PPG + HR + ACC + magHR (best model)	120,224	0.89G	496,128