BrainFlow指令时间

通过做实验，获得以下认识：

• stop stream和 start stream指令的执行时间差不多是2.03秒多，不到2.05秒

• present_stimulus中的这部分代码的执行时间约为stimulus_duration + 0.3~0.6 秒

while now_time < stimulus_duration:
    now_time = timer.getTime()
    # 通过改变对比度来实现闪烁
    for i,block in enumerate(self.block_list):
        block.contrast = np.sin(2 * np.pi * now_time * stimulus_frquencies[i])
    self.win.flip()

• 当以start_stream()--present_stimulus()--stop_stream()方式执行代码：

stimulus_duration
0.8	准备执行start stream	1652406809.61434
数据起始	开始stream 准备执行present stimulus	1652406811.64998	2.035640001297
	start flip	1652406811.64998
	end flip	1652406812.50566	0.855679988861084
	结束闪烁，准备关闭stream	1652406812.50566		数据量
	关闭stream	1652406814.55073	2.04506993293762	2862
0.9	准备执行start stream	1652406814.57498
数据起始	开始stream 准备执行present stimulus	1652406816.60762	2.03263998031616
	start flip	1652406816.60762
	end flip	1652406817.54393	0.936310052871704
	结束闪烁，准备关闭stream	1652406817.54393		数据量
	关闭stream	1652406819.58273	2.03880000114441	2974
1	准备执行start stream	1652406819.59472
	开始stream 准备执行present stimulus	1652406821.62517
	start flip	1652406821.62517
	end flip	1652406822.68821	1.06304001808167
	结束闪烁，准备关闭stream	1652406822.68821		数据量
	关闭stream	1652406824.7225	2.03429007530212	3097
1.1	准备执行start stream	1652406824.72537
	开始stream 准备执行present stimulus	1652406826.76183
	start flip	1652406826.76183
	end flip	1652406827.92962	1.16778993606567
	结束闪烁，准备关闭stream	1652406827.92962		数据量
	关闭stream	1652406829.97415	2.04452991485596	3204
1.2	准备执行start stream	1652406829.97914
	开始stream 准备执行present stimulus	1652406832.01399
	start flip	1652406832.01399
	end flip	1652406833.26952	1.25553011894226
	结束闪烁，准备关闭stream	1652406833.26952		数据量
	关闭stream	1652406835.30174	2.03221988677979	3300
1.3	准备执行start stream	1652406835.30874
	开始stream 准备执行present stimulus	1652406837.33626
	start flip	1652406837.33626
	end flip	1652406838.68086	1.3445999622345
	结束闪烁，准备关闭stream	1652406838.68086		数据量
	关闭stream	1652406840.71767	2.03680992126465	3369
1.4	准备执行start stream	1652406840.72067
	开始stream 准备执行present stimulus	1652406842.75228
	start flip	1652406842.75228
	end flip	1652406844.18768	1.43540000915527
	结束闪烁，准备关闭stream	1652406844.18768		数据量
	关闭stream	1652406846.22736	2.03968000411987	3485
1.5	准备执行start stream	1652406846.23036
	开始stream 准备执行present stimulus	1652406848.26315
	start flip	1652406848.26315
	end flip	1652406849.79622	1.53307008743286
	结束闪烁，准备关闭stream	1652406849.79622		数据量
	关闭stream	1652406851.83311	2.03689002990723	3560
1.6	准备执行start stream	1652406851.83908
	开始stream 准备执行present stimulus	1652406853.87572
	start flip	1652406853.87572
	end flip	1652406855.53883	1.66311001777649
	结束闪烁，准备关闭stream	1652406855.53883		数据量
	关闭stream	1652406857.57411	2.03527998924255	3694
1.7	准备执行start stream	1652406857.57711
	开始stream 准备执行present stimulus	1652406859.61192
	start flip	1652406859.61192
	end flip	1652406861.34773	1.73580980300903
	结束闪烁，准备关闭stream	1652406861.34773		数据量
	关闭stream	1652406863.38401	2.03628015518188	3772