Camera Time Synchronization

omarhassan · September 16, 2025, 10:33am

Hi,

I am running a multi_camera.py python sample script with four ZED X stereo cameras. The cameras are running at 1080p@30FPS. I modified the script with a small addition to print timestamp difference from four cameras and removed the image visualization log and when I print their differences, I find that the timestamp difference is usually not less than 1/fps i.e. it is around 0.07 - 0.12. Which leads me to believe that the frames are not synchronized. For reference, I have attached the script I am running. Also, here is hardware and software I am using:

Hardware:

1x ZED BOX Orin NX 16GB, 1 TB, No GPS
4x ZED X Stereo Camera No polarizer, 2.2mm focal length
4x GMSL2 Fakra Extension Cable M-F, 10 meter

Software:

Jetson Linux v36.3.0
Jetpack 6.0
Camera Driver: stereolabs-zedbox-duo_1.3.1-LI-MAX96712-all-ZEDBOX-L4T36.3.0_arm64
SDK: 5.0.5

multi_camera.py (4.2 KB)

Myzhar · September 16, 2025, 1:45pm

Hi @omarhassan

GMLS2 data is serialized. The timestamp is assigned to each data frame when it’s fully received by the deserializer.
For this reason, data samples from multiple cameras cannot have the same timestamp, even if they have been acquired at the same moment.
We guarantee that the cameras are synchronized by triggering them all with the same electronic signal. This guarantees that the synchronization accuracy is around 15 µsec.

As long as the timestamp difference between consecutive frames is lower than the grab period (T=1/FPS sec) you can consider the frames as synchronized.
In your case, the maximum time period is 33.3 msec, 0.0333 sec

According to what I’ve said above, this is not expected.
At first sight, your code does not guarantee that you are comparing the timestamps of frames acquired in the same grab period.

Can you please send the output of a run of the code?

omarhassan · September 16, 2025, 2:52pm

Hi,

Thank you for your reply! I modified the attached script a bit so that its easy to explain what I mean. Here is the code snippet I am using to print the timestamp in multi_camera.py main():

def min_pairwise_diffs(timestamps):
    n = len(timestamps)
    result = []
    for i in range(n):
        diffs = []
        for j in range(n):
            if i != j:  # skip self-difference
                diffs.append(abs(timestamps[i] - timestamps[j]))
        result.append(min(diffs) if diffs else 0)
    return result

...

def main():
    ...
    ts_tmp = []
    while True:
        if len(timestamp_list) < 4:
            continue
        if ts_tmp == timestamp_list:
            continue
        ts_tmp = timestamp_list.copy()
        
        print(f'Timestamp list (nanoseconds): ', np.array(timestamp_list))
        print(f'Timestamp difference (seconds): ', np.array(min_pairwise_diffs(timestamp_list))*10**-9)
        print('*'*50)
        time.sleep(0.001)

Here is a truncated output from the code:

Timestamp list (nanoseconds):  [1758033682911583294 1758033682874305028 1758033682766571680
 1758033682820550342]
Timestamp difference (seconds):  [0.03727827 0.03727827 0.05397866 0.05375469]
**************************************************
Timestamp list (nanoseconds):  [1758033682911583294 1758033682874305028 1758033682963142355
 1758033682820550342]
Timestamp difference (seconds):  [0.03727827 0.03727827 0.05155906 0.05375469]
**************************************************
Timestamp list (nanoseconds):  [1758033682911583294 1758033682874305028 1758033682963142355
 1758033683017637610]
Timestamp difference (seconds):  [0.03727827 0.03727827 0.05155906 0.05449526]
**************************************************
Timestamp list (nanoseconds):  [1758033682911583294 1758033683075227144 1758033682963142355
 1758033683017637610]
Timestamp difference (seconds):  [0.05155906 0.05758953 0.05155906 0.05449526]
**************************************************
Timestamp list (nanoseconds):  [1758033683109941548 1758033683075227144 1758033682963142355
 1758033683017637610]
Timestamp difference (seconds):  [0.0347144  0.0347144  0.05449526 0.05449526]
**************************************************
Timestamp list (nanoseconds):  [1758033683109941548 1758033683075227144 1758033683151827935
 1758033683017637610]
Timestamp difference (seconds):  [0.0347144  0.0347144  0.04188639 0.05758953]
**************************************************
Timestamp list (nanoseconds):  [1758033683109941548 1758033683075227144 1758033683151827935
 1758033683219826680]
Timestamp difference (seconds):  [0.0347144  0.0347144  0.04188639 0.06799874]
**************************************************
Timestamp list (nanoseconds):  [1758033683109941548 1758033683268744341 1758033683151827935
 1758033683219826680]
Timestamp difference (seconds):  [0.04188639 0.04891766 0.04188639 0.04891766]
**************************************************
Timestamp list (nanoseconds):  [1758033683305391098 1758033683268744341 1758033683151827935
 1758033683219826680]
Timestamp difference (seconds):  [0.03664676 0.03664676 0.06799874 0.04891766]
**************************************************
Timestamp list (nanoseconds):  [1758033683305391098 1758033683268744341 1758033683356756264
 1758033683219826680]
Timestamp difference (seconds):  [0.03664676 0.03664676 0.05136517 0.04891766]
**************************************************
Timestamp list (nanoseconds):  [1758033683305391098 1758033683268744341 1758033683356756264
 1758033683419597557]
Timestamp difference (seconds):  [0.03664676 0.03664676 0.05136517 0.06284129]
**************************************************
Timestamp list (nanoseconds):  [1758033683305391098 1758033683466001247 1758033683356756264
 1758033683419597557]
Timestamp difference (seconds):  [0.05136517 0.04640369 0.05136517 0.04640369]
**************************************************
Timestamp list (nanoseconds):  [1758033683516215399 1758033683466001247 1758033683356756264
 1758033683419597557]
Timestamp difference (seconds):  [0.05021415 0.04640369 0.06284129 0.04640369]
**************************************************
Timestamp list (nanoseconds):  [1758033683516215399 1758033683466001247 1758033683560046843
 1758033683419597557]
Timestamp difference (seconds):  [0.04383144 0.04640369 0.04383144 0.04640369]
**************************************************
Timestamp list (nanoseconds):  [1758033683516215399 1758033683466001247 1758033683560046843
 1758033683613501455]
Timestamp difference (seconds):  [0.04383144 0.05021415 0.04383144 0.05345461]
**************************************************
Timestamp list (nanoseconds):  [1758033683516215399 1758033683651080627 1758033683560046843
 1758033683613501455]
Timestamp difference (seconds):  [0.04383144 0.03757917 0.04383144 0.03757917]
**************************************************
Timestamp list (nanoseconds):  [1758033683711340906 1758033683651080627 1758033683560046843
 1758033683613501455]
Timestamp difference (seconds):  [0.06026028 0.03757917 0.05345461 0.03757917]
**************************************************
Timestamp list (nanoseconds):  [1758033683711340906 1758033683651080627 1758033683769897608
 1758033683613501455]
Timestamp difference (seconds):  [0.0585567  0.03757917 0.0585567  0.03757917]
**************************************************
Timestamp list (nanoseconds):  [1758033683711340906 1758033683651080627 1758033683769897608
 1758033683809751672]
Timestamp difference (seconds):  [0.0585567  0.06026028 0.03985406 0.03985406]
**************************************************
Timestamp list (nanoseconds):  [1758033683711340906 1758033683843422617 1758033683769897608
 1758033683809751672]
Timestamp difference (seconds):  [0.0585567  0.03367095 0.03985406 0.03367095]
**************************************************
Timestamp list (nanoseconds):  [1758033683912435763 1758033683843422617 1758033683769897608
 1758033683809751672]
Timestamp difference (seconds):  [0.06901315 0.03367095 0.03985406 0.03367095]
**************************************************
Timestamp list (nanoseconds):  [1758033683912435763 1758033683843422617 1758033683968019055
 1758033683809751672]
Timestamp difference (seconds):  [0.05558329 0.03367095 0.05558329 0.03367095]
**************************************************
Timestamp list (nanoseconds):  [1758033683912435763 1758033683843422617 1758033683968019055
 1758033684001012218]
Timestamp difference (seconds):  [0.05558329 0.06901315 0.03299316 0.03299316]
**************************************************
Timestamp list (nanoseconds):  [1758033683912435763 1758033684050385254 1758033683968019055
 1758033684001012218]
Timestamp difference (seconds):  [0.05558329 0.04937304 0.03299316 0.03299316]
**************************************************
Timestamp list (nanoseconds):  [1758033684121197916 1758033684050385254 1758033683968019055
 1758033684001012218]
Timestamp difference (seconds):  [0.07081266 0.04937304 0.03299316 0.03299316]
**************************************************
Timestamp list (nanoseconds):  [1758033684121197916 1758033684050385254 1758033684161957130
 1758033684001012218]
Timestamp difference (seconds):  [0.04075921 0.04937304 0.04075921 0.04937304]
**************************************************
Timestamp list (nanoseconds):  [1758033684121197916 1758033684050385254 1758033684161957130
 1758033684195506919]
Timestamp difference (seconds):  [0.04075921 0.07081266 0.03354979 0.03354979]
**************************************************
Timestamp list (nanoseconds):  [1758033684121197916 1758033684255335600 1758033684161957130
 1758033684195506919]
Timestamp difference (seconds):  [0.04075921 0.05982868 0.03354979 0.03354979]
**************************************************
Timestamp list (nanoseconds):  [1758033684318397700 1758033684255335600 1758033684161957130
 1758033684195506919]
Timestamp difference (seconds):  [0.0630621  0.05982868 0.03354979 0.03354979]
**************************************************
Timestamp list (nanoseconds):  [1758033684318397700 1758033684255335600 1758033684353611897
 1758033684195506919]
Timestamp difference (seconds):  [0.0352142  0.05982868 0.0352142  0.05982868]
**************************************************
Timestamp list (nanoseconds):  [1758033684318397700 1758033684255335600 1758033684353611897
 1758033684389891857]
Timestamp difference (seconds):  [0.0352142  0.0630621  0.0352142  0.03627996]
**************************************************
Timestamp list (nanoseconds):  [1758033684318397700 1758033684459751720 1758033684353611897
 1758033684389891857]
Timestamp difference (seconds):  [0.0352142  0.06985986 0.0352142  0.03627996]
**************************************************
Timestamp list (nanoseconds):  [1758033684515236928 1758033684459751720 1758033684353611897
 1758033684389891857]
Timestamp difference (seconds):  [0.05548521 0.05548521 0.03627996 0.03627996]
**************************************************
Timestamp list (nanoseconds):  [1758033684515236928 1758033684459751720 1758033684550920100
 1758033684389891857]
Timestamp difference (seconds):  [0.03568317 0.05548521 0.03568317 0.06985986]
**************************************************
Timestamp list (nanoseconds):  [1758033684515236928 1758033684459751720 1758033684550920100
 1758033684594573970]
Timestamp difference (seconds):  [0.03568317 0.05548521 0.03568317 0.04365387]
**************************************************
Timestamp list (nanoseconds):  [1758033684515236928 1758033684667571794 1758033684550920100
 1758033684594573970]
Timestamp difference (seconds):  [0.03568317 0.07299782 0.03568317 0.04365387]
**************************************************
Timestamp list (nanoseconds):  [1758033684708371840 1758033684667571794 1758033684550920100
 1758033684594573970]
Timestamp difference (seconds):  [0.04080005 0.04080005 0.04365387 0.04365387]
**************************************************
Timestamp list (nanoseconds):  [1758033684708371840 1758033684667571794 1758033684752982958
 1758033684594573970]
Timestamp difference (seconds):  [0.04080005 0.04080005 0.04461112 0.07299782]
**************************************************
Timestamp list (nanoseconds):  [1758033684708371840 1758033684667571794 1758033684752982958
 1758033684793804894]
Timestamp difference (seconds):  [0.04080005 0.04080005 0.04082194 0.04082194]
**************************************************
Timestamp list (nanoseconds):  [1758033684708371840 1758033684867090407 1758033684752982958
 1758033684793804894]
Timestamp difference (seconds):  [0.04461112 0.07328551 0.04082194 0.04082194]
**************************************************
Timestamp list (nanoseconds):  [1758033684905982454 1758033684867090407 1758033684752982958
 1758033684793804894]
Timestamp difference (seconds):  [0.03889205 0.03889205 0.04082194 0.04082194]
**************************************************
Timestamp list (nanoseconds):  [1758033684905982454 1758033684867090407 1758033684946454330
 1758033684793804894]
Timestamp difference (seconds):  [0.03889205 0.03889205 0.04047188 0.07328551]
**************************************************
Timestamp list (nanoseconds):  [1758033684905982454 1758033684867090407 1758033684946454330
 1758033684990530134]
Timestamp difference (seconds):  [0.03889205 0.03889205 0.04047188 0.0440758 ]
**************************************************
Timestamp list (nanoseconds):  [1758033684905982454 1758033685070604481 1758033684946454330
 1758033684990530134]
Timestamp difference (seconds):  [0.04047188 0.08007435 0.04047188 0.0440758 ]
**************************************************
Timestamp list (nanoseconds):  [1758033685094363320 1758033685070604481 1758033684946454330
 1758033684990530134]
Timestamp difference (seconds):  [0.02375884 0.02375884 0.0440758  0.0440758 ]
**************************************************
Timestamp list (nanoseconds):  [1758033685094363320 1758033685070604481 1758033685136045220
 1758033684990530134]
Timestamp difference (seconds):  [0.02375884 0.02375884 0.0416819  0.08007435]
**************************************************
Timestamp list (nanoseconds):  [1758033685094363320 1758033685070604481 1758033685136045220
 1758033685186542262]
Timestamp difference (seconds):  [0.02375884 0.02375884 0.0416819  0.05049704]
**************************************************
Timestamp list (nanoseconds):  [1758033685287630301 1758033685282458769 1758033685136045220
 1758033685186542262]
Timestamp difference (seconds):  [0.00517153 0.00517153 0.05049704 0.05049704]
**************************************************
Timestamp list (nanoseconds):  [1758033685287630301 1758033685282458769 1758033685327335079
 1758033685186542262]
Timestamp difference (seconds):  [0.00517153 0.00517153 0.03970478 0.09591651]
**************************************************
Timestamp list (nanoseconds):  [1758033685287630301 1758033685282458769 1758033685327335079
 1758033685407649690]
Timestamp difference (seconds):  [0.00517153 0.00517153 0.03970478 0.08031461]
**************************************************
Timestamp list (nanoseconds):  [1758033685477166437 1758033685282458769 1758033685327335079
 1758033685407649690]
Timestamp difference (seconds):  [0.06951675 0.04487631 0.04487631 0.06951675]
**************************************************
Timestamp list (nanoseconds):  [1758033685477166437 1758033685478151910 1758033685327335079
 1758033685407649690]
Timestamp difference (seconds):  [0.00098547 0.00098547 0.08031461 0.06951675]
**************************************************
Timestamp list (nanoseconds):  [1758033685477166437 1758033685478151910 1758033685527871230
 1758033685407649690]
Timestamp difference (seconds):  [0.00098547 0.00098547 0.04971932 0.06951675]
**************************************************
Timestamp list (nanoseconds):  [1758033685477166437 1758033685478151910 1758033685527871230
 1758033685617838035]
Timestamp difference (seconds):  [0.00098547 0.00098547 0.04971932 0.08996681]
**************************************************
Timestamp list (nanoseconds):  [1758033685666992888 1758033685661817323 1758033685527871230
 1758033685617838035]
Timestamp difference (seconds):  [0.00517557 0.00517557 0.08996681 0.04397929]
**************************************************
Timestamp list (nanoseconds):  [1758033685666992888 1758033685661817323 1758033685731733924
 1758033685617838035]
Timestamp difference (seconds):  [0.00517557 0.00517557 0.06474104 0.04397929]
**************************************************
Timestamp list (nanoseconds):  [1758033685666992888 1758033685661817323 1758033685731733924
 1758033685810233626]
Timestamp difference (seconds):  [0.00517557 0.00517557 0.06474104 0.0784997 ]
**************************************************
Timestamp list (nanoseconds):  [1758033685862998680 1758033685661817323 1758033685731733924
 1758033685810233626]
Timestamp difference (seconds):  [0.05276505 0.0699166  0.0699166  0.05276505]
**************************************************
Timestamp list (nanoseconds):  [1758033685862998680 1758033685878454331 1758033685731733924
 1758033685810233626]
Timestamp difference (seconds):  [0.01545565 0.01545565 0.0784997  0.05276505]
**************************************************
Timestamp list (nanoseconds):  [1758033685862998680 1758033685878454331 1758033685928823336
 1758033685810233626]
Timestamp difference (seconds):  [0.01545565 0.01545565 0.05036901 0.05276505]
**************************************************
Timestamp list (nanoseconds):  [1758033685862998680 1758033685878454331 1758033685928823336
 1758033686005735178]
Timestamp difference (seconds):  [0.01545565 0.01545565 0.05036901 0.07691184]
**************************************************
Timestamp list (nanoseconds):  [1758033686062595567 1758033685878454331 1758033685928823336
 1758033686005735178]
Timestamp difference (seconds):  [0.05686039 0.05036901 0.05036901 0.05686039]
**************************************************
Timestamp list (nanoseconds):  [1758033686062595567 1758033686082154363 1758033685928823336
 1758033686005735178]
Timestamp difference (seconds):  [0.0195588  0.0195588  0.07691184 0.05686039]
**************************************************
Timestamp list (nanoseconds):  [1758033686062595567 1758033686082154363 1758033686117285677
 1758033686005735178]
Timestamp difference (seconds):  [0.0195588  0.0195588  0.03513131 0.05686039]
**************************************************
Timestamp list (nanoseconds):  [1758033686062595567 1758033686082154363 1758033686117285677
 1758033686204415139]
Timestamp difference (seconds):  [0.0195588  0.0195588  0.03513131 0.08712946]
**************************************************
Timestamp list (nanoseconds):  [1758033686261309354 1758033686082154363 1758033686117285677
 1758033686204415139]
Timestamp difference (seconds):  [0.05689422 0.03513131 0.03513131 0.05689422]
**************************************************
Timestamp list (nanoseconds):  [1758033686261309354 1758033686277875569 1758033686117285677
 1758033686204415139]
Timestamp difference (seconds):  [0.01656622 0.01656622 0.08712946 0.05689422]
**************************************************
Timestamp list (nanoseconds):  [1758033686261309354 1758033686277875569 1758033686317026185
 1758033686204415139]
Timestamp difference (seconds):  [0.01656622 0.01656622 0.03915062 0.05689422]
**************************************************
Timestamp list (nanoseconds):  [1758033686261309354 1758033686277875569 1758033686317026185
 1758033686402594315]
Timestamp difference (seconds):  [0.01656622 0.01656622 0.03915062 0.08556813]
**************************************************
Timestamp list (nanoseconds):  [1758033686455951036 1758033686277875569 1758033686317026185
 1758033686402594315]
Timestamp difference (seconds):  [0.05335672 0.03915062 0.03915062 0.05335672]
**************************************************

In the output, the timestamp list is getting updated one element at a time through grab_run thread. I understand that timestamp list is updating sequentially and it does not represent the same grab_period for all cameras however, I expect that at least one element of timestamp difference be less than 0.03333 (if any two cameras match grab_period, their timestamp should be close enough). But as you can see from the output, that is not the case, most of the time. Also, is there any built-in function in the SDK to check grab_period for the camera to match camera frames better? As you mentioned in GMSL2 case, the timestamps are not matching.

Myzhar · September 16, 2025, 3:07pm

@omarhassan I’ve found the issue:

timestamp_list[index] = zed_list[index].get_timestamp(sl.TIME_REFERENCE.CURRENT).data_ns

if you use sl.TIME_REFERENCE.CURRENT you retrieve the system timestamp at the moment when you call the function.

You must use sl.TIME_REFERENCE.IMAGE to retrieve the latest data grab timestamp.

omarhassan · September 16, 2025, 3:29pm

By changing the reference in get_timestamp function, I get somewhat predictable outputs:

Timestamp list (nanoseconds):  [1758035389649059000 1758035389582349000 1758035389449227000
 1758035389549186000]
Timestamp difference (seconds):  [0.06671  0.033163 0.099959 0.033163]
**************************************************
Timestamp list (nanoseconds):  [1758035389649059000 1758035389582349000 1758035389649227000
 1758035389549186000]
Timestamp difference (seconds):  [0.000168 0.033163 0.000168 0.033163]
**************************************************
Timestamp list (nanoseconds):  [1758035389649059000 1758035389582349000 1758035389649227000
 1758035389749295000]
Timestamp difference (seconds):  [0.000168 0.06671  0.000168 0.100068]
**************************************************
Timestamp list (nanoseconds):  [1758035389649059000 1758035389782424000 1758035389649227000
 1758035389749295000]
Timestamp difference (seconds):  [0.000168 0.033129 0.000168 0.033129]
**************************************************
Timestamp list (nanoseconds):  [1758035389815690000 1758035389782424000 1758035389649227000
 1758035389749295000]
Timestamp difference (seconds):  [0.033266 0.033129 0.100068 0.033129]
**************************************************
Timestamp list (nanoseconds):  [1758035389815690000 1758035389782424000 1758035389849331000
 1758035389749295000]
Timestamp difference (seconds):  [0.033266 0.033129 0.033641 0.033129]
**************************************************
Timestamp list (nanoseconds):  [1758035389815690000 1758035389782424000 1758035389849331000
 1758035389949243000]
Timestamp difference (seconds):  [0.033266 0.033266 0.033641 0.099912]
**************************************************
Timestamp list (nanoseconds):  [1758035389815690000 1758035389982404000 1758035389849331000
 1758035389949243000]
Timestamp difference (seconds):  [0.033641 0.033161 0.033641 0.033161]
**************************************************
Timestamp list (nanoseconds):  [1758035389815690000 1758035389982404000 1758035390015753000
 1758035389949243000]
Timestamp difference (seconds):  [0.133553 0.033161 0.033349 0.033161]
**************************************************
Timestamp list (nanoseconds):  [1758035390049029000 1758035389982404000 1758035390015753000
 1758035389949243000]
Timestamp difference (seconds):  [0.033276 0.033161 0.033276 0.033161]
**************************************************
Timestamp list (nanoseconds):  [1758035390049029000 1758035389982404000 1758035390015753000
 1758035390149481000]
Timestamp difference (seconds):  [0.033276 0.033349 0.033276 0.100452]
**************************************************
Timestamp list (nanoseconds):  [1758035390049029000 1758035390182384000 1758035390015753000
 1758035390149481000]
Timestamp difference (seconds):  [0.033276 0.032903 0.033276 0.032903]
**************************************************
Timestamp list (nanoseconds):  [1758035390049029000 1758035390182384000 1758035390215726000
 1758035390149481000]
Timestamp difference (seconds):  [0.100452 0.032903 0.033342 0.032903]
**************************************************
Timestamp list (nanoseconds):  [1758035390249048000 1758035390182384000 1758035390215726000
 1758035390149481000]
Timestamp difference (seconds):  [0.033322 0.032903 0.033322 0.032903]
**************************************************
Timestamp list (nanoseconds):  [1758035390249048000 1758035390182384000 1758035390215726000
 1758035390348983000]
Timestamp difference (seconds):  [0.033322 0.033342 0.033322 0.099935]
**************************************************
Timestamp list (nanoseconds):  [1758035390249048000 1758035390382797000 1758035390215726000
 1758035390348983000]
Timestamp difference (seconds):  [0.033322 0.033814 0.033322 0.033814]
**************************************************
Timestamp list (nanoseconds):  [1758035390249048000 1758035390382797000 1758035390415700000
 1758035390348983000]
Timestamp difference (seconds):  [0.099935 0.032903 0.032903 0.033814]
**************************************************
Timestamp list (nanoseconds):  [1758035390415691000 1758035390382797000 1758035390415700000
 1758035390348983000]
Timestamp difference (seconds):  [9.0000e-06 3.2894e-02 9.0000e-06 3.3814e-02]
**************************************************
Timestamp list (nanoseconds):  [1758035390415691000 1758035390582321000 1758035390415700000
 1758035390348983000]
Timestamp difference (seconds):  [9.0000e-06 3.3271e-02 9.0000e-06 3.3271e-02]
**************************************************
Timestamp list (nanoseconds):  [1758035390415691000 1758035390582321000 1758035390415700000
 1758035390549050000]
Timestamp difference (seconds):  [9.0000e-06 3.3271e-02 9.0000e-06 3.3271e-02]
**************************************************
Timestamp list (nanoseconds):  [1758035390415691000 1758035390582321000 1758035390615718000
 1758035390549050000]
Timestamp difference (seconds):  [0.133359 0.033271 0.033397 0.033271]
**************************************************
Timestamp list (nanoseconds):  [1758035390682379000 1758035390582321000 1758035390615718000
 1758035390549050000]
Timestamp difference (seconds):  [0.066661 0.033271 0.033397 0.033271]
**************************************************
Timestamp list (nanoseconds):  [1758035390682379000 1758035390582321000 1758035390615718000
 1758035390782405000]
Timestamp difference (seconds):  [0.066661 0.033397 0.033397 0.100026]
**************************************************
Timestamp list (nanoseconds):  [1758035390682379000 1758035390782310000 1758035390615718000
 1758035390782405000]
Timestamp difference (seconds):  [6.6661e-02 9.5000e-05 6.6661e-02 9.5000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035390682379000 1758035390782310000 1758035390782495000
 1758035390782405000]
Timestamp difference (seconds):  [9.9931e-02 9.5000e-05 9.0000e-05 9.0000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035390882310000 1758035390782310000 1758035390782495000
 1758035390782405000]
Timestamp difference (seconds):  [9.9815e-02 9.5000e-05 9.0000e-05 9.0000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035390882310000 1758035390782310000 1758035390782495000
 1758035390949538000]
Timestamp difference (seconds):  [0.067228 0.000185 0.000185 0.067228]
**************************************************
Timestamp list (nanoseconds):  [1758035390882310000 1758035390949222000 1758035390782495000
 1758035390949538000]
Timestamp difference (seconds):  [0.066912 0.000316 0.099815 0.000316]
**************************************************
Timestamp list (nanoseconds):  [1758035390882310000 1758035390949222000 1758035390982368000
 1758035390949538000]
Timestamp difference (seconds):  [0.066912 0.000316 0.03283  0.000316]
**************************************************
Timestamp list (nanoseconds):  [1758035391048988000 1758035390949222000 1758035390982368000
 1758035390949538000]
Timestamp difference (seconds):  [0.06662  0.000316 0.03283  0.000316]
**************************************************
Timestamp list (nanoseconds):  [1758035391048988000 1758035390949222000 1758035390982368000
 1758035391149230000]
Timestamp difference (seconds):  [0.06662  0.033146 0.033146 0.100242]
**************************************************
Timestamp list (nanoseconds):  [1758035391048988000 1758035391149209000 1758035390982368000
 1758035391149230000]
Timestamp difference (seconds):  [6.662e-02 2.100e-05 6.662e-02 2.100e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035391048988000 1758035391149209000 1758035391215837000
 1758035391149230000]
Timestamp difference (seconds):  [1.00221e-01 2.10000e-05 6.66070e-02 2.10000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035391282462000 1758035391149209000 1758035391215837000
 1758035391149230000]
Timestamp difference (seconds):  [6.6625e-02 2.1000e-05 6.6607e-02 2.1000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035391282462000 1758035391149209000 1758035391215837000
 1758035391349334000]
Timestamp difference (seconds):  [0.066625 0.066628 0.066625 0.066872]
**************************************************
Timestamp list (nanoseconds):  [1758035391282462000 1758035391349043000 1758035391215837000
 1758035391349334000]
Timestamp difference (seconds):  [0.066581 0.000291 0.066625 0.000291]
**************************************************
Timestamp list (nanoseconds):  [1758035391282462000 1758035391349043000 1758035391415753000
 1758035391349334000]
Timestamp difference (seconds):  [0.066581 0.000291 0.066419 0.000291]
**************************************************
Timestamp list (nanoseconds):  [1758035391482403000 1758035391349043000 1758035391415753000
 1758035391349334000]
Timestamp difference (seconds):  [0.06665  0.000291 0.066419 0.000291]
**************************************************
Timestamp list (nanoseconds):  [1758035391482403000 1758035391515675000 1758035391415753000
 1758035391349334000]
Timestamp difference (seconds):  [0.033272 0.033272 0.066419 0.066419]
**************************************************
Timestamp list (nanoseconds):  [1758035391482403000 1758035391515675000 1758035391415753000
 1758035391515690000]
Timestamp difference (seconds):  [3.3272e-02 1.5000e-05 6.6650e-02 1.5000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035391482403000 1758035391515675000 1758035391615697000
 1758035391515690000]
Timestamp difference (seconds):  [3.32720e-02 1.50000e-05 1.00007e-01 1.50000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035391715651000 1758035391715682000 1758035391615697000
 1758035391515690000]
Timestamp difference (seconds):  [3.10000e-05 3.10000e-05 9.99540e-02 1.00007e-01]
**************************************************
Timestamp list (nanoseconds):  [1758035391715651000 1758035391715682000 1758035391615697000
 1758035391715690000]
Timestamp difference (seconds):  [3.1000e-05 8.0000e-06 9.9954e-02 8.0000e-06]
**************************************************
Timestamp list (nanoseconds):  [1758035391715651000 1758035391715682000 1758035391815845000
 1758035391715690000]
Timestamp difference (seconds):  [3.10000e-05 8.00000e-06 1.00155e-01 8.00000e-06]
**************************************************
Timestamp list (nanoseconds):  [1758035391915644000 1758035391915735000 1758035391815845000
 1758035391715690000]
Timestamp difference (seconds):  [9.10000e-05 9.10000e-05 9.97990e-02 1.00155e-01]
**************************************************
Timestamp list (nanoseconds):  [1758035391915644000 1758035391915735000 1758035391815845000
 1758035391915968000]
Timestamp difference (seconds):  [9.1000e-05 9.1000e-05 9.9799e-02 2.3300e-04]
**************************************************
Timestamp list (nanoseconds):  [1758035391915644000 1758035391915735000 1758035392015708000
 1758035391915968000]
Timestamp difference (seconds):  [9.100e-05 9.100e-05 9.974e-02 2.330e-04]
**************************************************
Timestamp list (nanoseconds):  [1758035391915644000 1758035391915735000 1758035392015708000
 1758035392115683000]
Timestamp difference (seconds):  [9.1000e-05 9.1000e-05 9.9973e-02 9.9975e-02]
**************************************************
Timestamp list (nanoseconds):  [1758035392115632000 1758035391915735000 1758035392015708000
 1758035392115683000]
Timestamp difference (seconds):  [5.1000e-05 9.9973e-02 9.9924e-02 5.1000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035392115632000 1758035392115664000 1758035392015708000
 1758035392115683000]
Timestamp difference (seconds):  [3.2000e-05 1.9000e-05 9.9924e-02 1.9000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035392115632000 1758035392115664000 1758035392215677000
 1758035392115683000]
Timestamp difference (seconds):  [3.2000e-05 1.9000e-05 9.9994e-02 1.9000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035392115632000 1758035392115664000 1758035392215677000
 1758035392315962000]
Timestamp difference (seconds):  [3.20000e-05 3.20000e-05 1.00013e-01 1.00285e-01]
**************************************************
Timestamp list (nanoseconds):  [1758035392315589000 1758035392115664000 1758035392215677000
 1758035392315962000]
Timestamp difference (seconds):  [0.000373 0.100013 0.099912 0.000373]
**************************************************
Timestamp list (nanoseconds):  [1758035392315589000 1758035392315646000 1758035392215677000
 1758035392315962000]
Timestamp difference (seconds):  [5.7000e-05 5.7000e-05 9.9912e-02 3.1600e-04]
**************************************************
Timestamp list (nanoseconds):  [1758035392315589000 1758035392315646000 1758035392415674000
 1758035392315962000]
Timestamp difference (seconds):  [5.7000e-05 5.7000e-05 9.9712e-02 3.1600e-04]
**************************************************
Timestamp list (nanoseconds):  [1758035392315589000 1758035392315646000 1758035392415674000
 1758035392482349000]
Timestamp difference (seconds):  [5.7000e-05 5.7000e-05 6.6675e-02 6.6675e-02]
**************************************************
Timestamp list (nanoseconds):  [1758035392482313000 1758035392315646000 1758035392415674000
 1758035392482349000]
Timestamp difference (seconds):  [3.60000e-05 1.00028e-01 6.66390e-02 3.60000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035392482313000 1758035392582336000 1758035392415674000
 1758035392482349000]
Timestamp difference (seconds):  [3.6000e-05 9.9987e-02 6.6639e-02 3.6000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035392482313000 1758035392582336000 1758035392615945000
 1758035392482349000]
Timestamp difference (seconds):  [3.6000e-05 3.3609e-02 3.3609e-02 3.6000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035392482313000 1758035392582336000 1758035392615945000
 1758035392682287000]
Timestamp difference (seconds):  [0.100023 0.033609 0.033609 0.066342]
**************************************************
Timestamp list (nanoseconds):  [1758035392715643000 1758035392582336000 1758035392615945000
 1758035392682287000]
Timestamp difference (seconds):  [0.033356 0.033609 0.033609 0.033356]
**************************************************
Timestamp list (nanoseconds):  [1758035392715643000 1758035392749026000 1758035392615945000
 1758035392682287000]
Timestamp difference (seconds):  [0.033356 0.033383 0.066342 0.033356]
**************************************************
Timestamp list (nanoseconds):  [1758035392715643000 1758035392749026000 1758035392783316000
 1758035392682287000]
Timestamp difference (seconds):  [0.033356 0.033383 0.03429  0.033356]
**************************************************
Timestamp list (nanoseconds):  [1758035392715643000 1758035392749026000 1758035392783316000
 1758035392882322000]
Timestamp difference (seconds):  [0.033383 0.033383 0.03429  0.099006]
**************************************************
Timestamp list (nanoseconds):  [1758035392915617000 1758035392749026000 1758035392783316000
 1758035392882322000]
Timestamp difference (seconds):  [0.033295 0.03429  0.03429  0.033295]
**************************************************
Timestamp list (nanoseconds):  [1758035392915617000 1758035392948928000 1758035392783316000
 1758035392882322000]
Timestamp difference (seconds):  [0.033295 0.033311 0.099006 0.033295]
**************************************************
Timestamp list (nanoseconds):  [1758035392915617000 1758035392948928000 1758035393016109000
 1758035392882322000]
Timestamp difference (seconds):  [0.033295 0.033311 0.067181 0.033295]
**************************************************
Timestamp list (nanoseconds):  [1758035392915617000 1758035392948928000 1758035393016109000
 1758035393082352000]
Timestamp difference (seconds):  [0.033311 0.033311 0.066243 0.066243]
**************************************************
Timestamp list (nanoseconds):  [1758035393115575000 1758035392948928000 1758035393016109000
 1758035393082352000]
Timestamp difference (seconds):  [0.033223 0.067181 0.066243 0.033223]
**************************************************
Timestamp list (nanoseconds):  [1758035393115575000 1758035393148928000 1758035393016109000
 1758035393082352000]
Timestamp difference (seconds):  [0.033223 0.033353 0.066243 0.033223]
**************************************************
Timestamp list (nanoseconds):  [1758035393115575000 1758035393148928000 1758035393215771000
 1758035393082352000]
Timestamp difference (seconds):  [0.033223 0.033353 0.066843 0.033223]
**************************************************
Timestamp list (nanoseconds):  [1758035393115575000 1758035393148928000 1758035393215771000
 1758035393282327000]
Timestamp difference (seconds):  [0.033353 0.033353 0.066556 0.066556]
**************************************************
Timestamp list (nanoseconds):  [1758035393315597000 1758035393148928000 1758035393215771000
 1758035393282327000]
Timestamp difference (seconds):  [0.03327  0.066843 0.066556 0.03327 ]
**************************************************
Timestamp list (nanoseconds):  [1758035393315597000 1758035393349133000 1758035393215771000
 1758035393282327000]
Timestamp difference (seconds):  [0.03327  0.033536 0.066556 0.03327 ]
**************************************************
Timestamp list (nanoseconds):  [1758035393315597000 1758035393349133000 1758035393415635000
 1758035393282327000]
Timestamp difference (seconds):  [0.03327  0.033536 0.066502 0.03327 ]
**************************************************
Timestamp list (nanoseconds):  [1758035393315597000 1758035393349133000 1758035393415635000
 1758035393482323000]
Timestamp difference (seconds):  [0.033536 0.033536 0.066502 0.066688]
**************************************************
Timestamp list (nanoseconds):  [1758035393515605000 1758035393349133000 1758035393415635000
 1758035393482323000]
Timestamp difference (seconds):  [0.033282 0.066502 0.066502 0.033282]
**************************************************
Timestamp list (nanoseconds):  [1758035393515605000 1758035393548945000 1758035393415635000
 1758035393482323000]
Timestamp difference (seconds):  [0.033282 0.03334  0.066688 0.033282]
**************************************************
Timestamp list (nanoseconds):  [1758035393515605000 1758035393548945000 1758035393616040000
 1758035393482323000]
Timestamp difference (seconds):  [0.033282 0.03334  0.067095 0.033282]
**************************************************
Timestamp list (nanoseconds):  [1758035393515605000 1758035393548945000 1758035393616040000
 1758035393682368000]
Timestamp difference (seconds):  [0.03334  0.03334  0.066328 0.066328]
**************************************************
Timestamp list (nanoseconds):  [1758035393715596000 1758035393548945000 1758035393616040000
 1758035393682368000]
Timestamp difference (seconds):  [0.033228 0.067095 0.066328 0.033228]
**************************************************
Timestamp list (nanoseconds):  [1758035393715596000 1758035393748955000 1758035393616040000
 1758035393682368000]
Timestamp difference (seconds):  [0.033228 0.033359 0.066328 0.033228]
**************************************************
Timestamp list (nanoseconds):  [1758035393715596000 1758035393748955000 1758035393815686000
 1758035393682368000]
Timestamp difference (seconds):  [0.033228 0.033359 0.066731 0.033228]
**************************************************
Timestamp list (nanoseconds):  [1758035393715596000 1758035393748955000 1758035393815686000
 1758035393849125000]
Timestamp difference (seconds):  [0.033359 0.033359 0.033439 0.033439]
**************************************************
Timestamp list (nanoseconds):  [1758035393915602000 1758035393748955000 1758035393815686000
 1758035393849125000]
Timestamp difference (seconds):  [0.066477 0.066731 0.033439 0.033439]
**************************************************
Timestamp list (nanoseconds):  [1758035393915602000 1758035393948932000 1758035393815686000
 1758035393849125000]
Timestamp difference (seconds):  [0.03333  0.03333  0.033439 0.033439]
**************************************************
Timestamp list (nanoseconds):  [1758035393915602000 1758035393948932000 1758035394015761000
 1758035393849125000]
Timestamp difference (seconds):  [0.03333  0.03333  0.066829 0.066477]
**************************************************
Timestamp list (nanoseconds):  [1758035393915602000 1758035393948932000 1758035394015761000
 1758035394049231000]
Timestamp difference (seconds):  [0.03333 0.03333 0.03347 0.03347]
**************************************************
Timestamp list (nanoseconds):  [1758035394115562000 1758035393948932000 1758035394015761000
 1758035394049231000]
Timestamp difference (seconds):  [0.066331 0.066829 0.03347  0.03347 ]
**************************************************
Timestamp list (nanoseconds):  [1758035394115562000 1758035394149037000 1758035394015761000
 1758035394049231000]
Timestamp difference (seconds):  [0.033475 0.033475 0.03347  0.03347 ]
**************************************************
Timestamp list (nanoseconds):  [1758035394115562000 1758035394149037000 1758035394215778000
 1758035394049231000]
Timestamp difference (seconds):  [0.033475 0.033475 0.066741 0.066331]
**************************************************
Timestamp list (nanoseconds):  [1758035394115562000 1758035394149037000 1758035394215778000
 1758035394249059000]
Timestamp difference (seconds):  [0.033475 0.033475 0.033281 0.033281]
**************************************************
Timestamp list (nanoseconds):  [1758035394282242000 1758035394149037000 1758035394215778000
 1758035394249059000]
Timestamp difference (seconds):  [0.033183 0.066741 0.033281 0.033183]
**************************************************
Timestamp list (nanoseconds):  [1758035394282242000 1758035394349077000 1758035394215778000
 1758035394249059000]
Timestamp difference (seconds):  [0.033183 0.066835 0.033281 0.033183]
**************************************************
Timestamp list (nanoseconds):  [1758035394282242000 1758035394349077000 1758035394449000000
 1758035394249059000]
Timestamp difference (seconds):  [0.033183 0.066835 0.099923 0.033183]
**************************************************
Timestamp list (nanoseconds):  [1758035394282242000 1758035394349077000 1758035394449000000
 1758035394449419000]
Timestamp difference (seconds):  [0.066835 0.066835 0.000419 0.000419]
**************************************************
Timestamp list (nanoseconds):  [1758035394482253000 1758035394349077000 1758035394449000000
 1758035394449419000]
Timestamp difference (seconds):  [0.032834 0.099923 0.000419 0.000419]
**************************************************
Timestamp list (nanoseconds):  [1758035394482253000 1758035394549106000 1758035394449000000
 1758035394449419000]
Timestamp difference (seconds):  [0.032834 0.066853 0.000419 0.000419]
**************************************************
Timestamp list (nanoseconds):  [1758035394482253000 1758035394549106000 1758035394449000000
 1758035394615675000]
Timestamp difference (seconds):  [6.6853e-02 6.6511e-02 5.8000e-05 5.8000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035394482253000 1758035394549106000 1758035394615617000
 1758035394615675000]
Timestamp difference (seconds):  [6.6853e-02 6.6511e-02 5.8000e-05 5.8000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035394682359000 1758035394549106000 1758035394615617000
 1758035394615675000]
Timestamp difference (seconds):  [6.6684e-02 6.6511e-02 5.8000e-05 5.8000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035394682359000 1758035394749092000 1758035394615617000
 1758035394615675000]
Timestamp difference (seconds):  [6.6684e-02 6.6733e-02 5.8000e-05 5.8000e-05]
**************************************************
Timestamp list (nanoseconds):  [1758035394682359000 1758035394749092000 1758035394615617000
 1758035394848996000]
Timestamp difference (seconds):  [0.066733 0.066733 0.066742 0.099904]
**************************************************
Timestamp list (nanoseconds):  [1758035394682359000 1758035394749092000 1758035394815533000
 1758035394848996000]
Timestamp difference (seconds):  [0.066733 0.066441 0.033463 0.033463]
**************************************************
Timestamp list (nanoseconds):  [1758035394882256000 1758035394749092000 1758035394815533000
 1758035394848996000]
Timestamp difference (seconds):  [0.03326  0.066441 0.033463 0.03326 ]
**************************************************
Timestamp list (nanoseconds):  [1758035394882256000 1758035394949115000 1758035394815533000
 1758035394848996000]
Timestamp difference (seconds):  [0.03326  0.066859 0.033463 0.03326 ]
**************************************************
Timestamp list (nanoseconds):  [1758035394882256000 1758035394949115000 1758035394815533000
 1758035395015520000]
Timestamp difference (seconds):  [0.066723 0.066405 0.066723 0.066405]
**************************************************
Timestamp list (nanoseconds):  [1758035394882256000 1758035394949115000 1758035395015837000
 1758035395015520000]
Timestamp difference (seconds):  [0.066859 0.066405 0.000317 0.000317]
**************************************************
Timestamp list (nanoseconds):  [1758035395082194000 1758035394949115000 1758035395015837000
 1758035395015520000]
Timestamp difference (seconds):  [0.066357 0.066405 0.000317 0.000317]
**************************************************

From the documentation:

“When requesting the TIME_REFERENCE.IMAGE timestamp, the UNIX nanosecond timestamp of the latest grabbed image will be returned.
This value corresponds to the time at which the entire image was available in the PC memory. As such, it ignores the communication time that corresponds to 2 or 3 frame-time based on the fps (ex: 33.3ms to 50ms at 60fps).”

But I am still confused in how I can get the synchronized frames as timestamps are not exact. For clarification, in my application, I am grabbing and publishing frames from cameras own separate thread to a different process through IPC. I want to be able to synchronize the frames in the other process which is going to be receiving these frames asynchronously. Since timestamps are not matching, what other way would you recommend I do the synchronization?

Myzhar · September 17, 2025, 10:05am

The four frames with a timestamp difference of less than a grab period all belong to the same capture trigger.