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Problems with timecode using multiple recorders and SYS option

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dvision
2018-08-13
2018-08-24
  • dvision

    dvision - 2018-08-13

    I am using multiple recorders with the SYS option for timecode and with chunking. First recorder is not syncing time, the rest are syncing with the fist one, via ntpd (ticking synchronisation). The problem is that after a couple of hours, apparently randomly, one of the recorders refuse to start a new chunk. The following message is shown in the recorder log:

    channel[1] Target tc 01:40:37:18 not found, buffer 01:40:35:22 - 01:40:38:06
    Could not start record - not all target timecodes found
    

    How can I mittigate this?
    Thank you in advance.

    EDIT:
    It seems that the problem is related to jumping with the chunk over midnight. Sorry for missleading you.
    in MAIN log:

    00:06:18.579 IngexRecorderImpl::Stop(), tc 00:06:18:13, post-roll 12
    00:06:18.612 IngexRecorderImpl::Start(), tc 00:06:19:00, pre-roll 0
    channel[0] Target tc 00:06:19:00 not found, buffer 00:06:16:06 - 00:06:18:15
    channel[1] Target tc 00:06:19:00 not found, buffer 00:06:16:06 - 00:06:18:15
    channel[2] Target tc 00:06:19:00 not found, buffer 00:06:16:06 - 00:06:18:15
    Could not start record - not all target timecodes found
    

    In INPUT log:

    input0 index 0 Timecode discontinuity: -2160000 frames missing - current 00:00:00:00, last 23:59:59:24
    00:06:19.072 input0 index 0 duration 22500 reached (total=22500 written=22500 dropped=0)
    

    Is there a logic implemented for this exception when the TC IN is greater than TC OUT?
    Can you please indicate the source file where it should be?
    Thank you in advance.

     

    Last edit: dvision 2018-08-13
  • John Fletcher

    John Fletcher - 2018-08-24

    I think the first problem is that because SYS timecode is not locked to the video, you might get timecode values skipped or repeated occasionally. In your example:

    channel[1] Target tc 01:40:37:18 not found, buffer 01:40:35:22 - 01:40:38:06
    Could not start record - not all target timecodes found
    

    I'm guessing that timecode 01:40:37:18 got skipped.

    In the second problem, I think it might be because you have a pre-roll of zero. The recorder expects the start timecode to be in the buffer but if the start timecode is "now", it might not have got into the buffer yet. (Although I can't remember if chunking mode overrides your pre-roll setting.)

    The "-2160000 frames missing" message at midnight is normal and can be ignored.

     
  • John Fletcher

    John Fletcher - 2018-08-24

    By the way, for the SYS problem, you might get better results if the recorders sync to an accurate time source. I don't know if your SDI is locked to a reference but if you can get NTP from the same reference, that would be ideal.

     

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