Ruben Brunk | 370e243 | 2014-10-14 18:33:23 -0700 | [diff] [blame] | 1 | # Copyright 2014 The Android Open Source Project |
| 2 | # |
| 3 | # Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | # you may not use this file except in compliance with the License. |
| 5 | # You may obtain a copy of the License at |
| 6 | # |
| 7 | # http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | # |
| 9 | # Unless required by applicable law or agreed to in writing, software |
| 10 | # distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | # See the License for the specific language governing permissions and |
| 13 | # limitations under the License. |
| 14 | |
| 15 | import its.image |
| 16 | import its.caps |
| 17 | import its.device |
| 18 | import its.objects |
| 19 | import os.path |
Yin-Chia Yeh | 2970012 | 2016-10-10 10:54:07 -0700 | [diff] [blame] | 20 | from matplotlib import pylab |
Ruben Brunk | 370e243 | 2014-10-14 18:33:23 -0700 | [diff] [blame] | 21 | import matplotlib |
| 22 | import matplotlib.pyplot |
| 23 | |
| 24 | def main(): |
| 25 | """Measure jitter in camera timestamps. |
| 26 | """ |
| 27 | NAME = os.path.basename(__file__).split(".")[0] |
| 28 | |
| 29 | # Pass/fail thresholds |
| 30 | MIN_AVG_FRAME_DELTA = 30 # at least 30ms delta between frames |
| 31 | MAX_VAR_FRAME_DELTA = 0.01 # variance of frame deltas |
| 32 | MAX_FRAME_DELTA_JITTER = 0.3 # max ms gap from the average frame delta |
| 33 | |
| 34 | with its.device.ItsSession() as cam: |
| 35 | props = cam.get_camera_properties() |
Yin-Chia Yeh | fbae37b | 2015-02-03 09:42:54 -0800 | [diff] [blame] | 36 | its.caps.skip_unless(its.caps.manual_sensor(props) and |
| 37 | its.caps.sensor_fusion(props)) |
Ruben Brunk | 370e243 | 2014-10-14 18:33:23 -0700 | [diff] [blame] | 38 | |
| 39 | req, fmt = its.objects.get_fastest_manual_capture_settings(props) |
| 40 | caps = cam.do_capture([req]*50, [fmt]) |
| 41 | |
| 42 | # Print out the millisecond delta between the start of each exposure |
| 43 | tstamps = [c['metadata']['android.sensor.timestamp'] for c in caps] |
| 44 | deltas = [tstamps[i]-tstamps[i-1] for i in range(1,len(tstamps))] |
| 45 | deltas_ms = [d/1000000.0 for d in deltas] |
| 46 | avg = sum(deltas_ms) / len(deltas_ms) |
| 47 | var = sum([d*d for d in deltas_ms]) / len(deltas_ms) - avg * avg |
| 48 | range0 = min(deltas_ms) - avg |
| 49 | range1 = max(deltas_ms) - avg |
| 50 | print "Average:", avg |
| 51 | print "Variance:", var |
| 52 | print "Jitter range:", range0, "to", range1 |
| 53 | |
| 54 | # Draw a plot. |
| 55 | pylab.plot(range(len(deltas_ms)), deltas_ms) |
| 56 | matplotlib.pyplot.savefig("%s_deltas.png" % (NAME)) |
| 57 | |
| 58 | # Test for pass/fail. |
| 59 | assert(avg > MIN_AVG_FRAME_DELTA) |
| 60 | assert(var < MAX_VAR_FRAME_DELTA) |
| 61 | assert(abs(range0) < MAX_FRAME_DELTA_JITTER) |
| 62 | assert(abs(range1) < MAX_FRAME_DELTA_JITTER) |
| 63 | |
| 64 | if __name__ == '__main__': |
| 65 | main() |
| 66 | |