timestamps-- too many of them

[Hannah Wirtshafter]

Hi all, I have more timestamps than I do TTL pulses, but I also have no dropped frames based on timestamps (all frame intervals are within 10% of expected, and I double checked with suggestions Tank's 2018 neuron paper). What are these extra timestamps? I need to be able to sync frame TSs with TTL pulses. thanks!

[Hannah Wirtshafter]

in doing a little more processing, it looks like there are about the same number of "too large" TTL intervals as there are too many timestamps. Unsure why there should be dropped TTLs?

[DCL]

Hi, we are having the same issues with a v4 miniscope: the CAI movies and the recorded timestamps match each other and the chosen framerate, but the TTLs that are output, although following any change in frame rate, do not match.

In particular, it seems as though a rise is generated for every other frame, and that the "ON" and "OFF" times are identical: could it be that it was intended for the TTL signals to encode frame timing both via rises and decays?

Thanks!

[Hannah Wirtshafter]

Honestly I stopped using the TTLs for anything except syncing the start of the video with the start of my other input. Otherwise I could not figure out their timing 

Excuse my brevity, sent from my iPhone

On Oct 26, 2023, at 10:39 AM, DCL <defenseci...@gmail.com> wrote:



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[Eric Melonakos]

Hi,

The rises and decays of the TTL both signal frame acquisition events.

Hannah, I have seen occasional TTL drops too. They are easy to spot since the TTL is generally very regular (e.g., there will be one 67 ms gap between TTLs in a 30 Hz recording and the rest will be between ~31-35 ms), so I just fill them in with my best guess of when they would have happened and then avoid any analyses of that period of time that need precise timing. In one example I just looked at, the TTL drop didn't coincide with a large timestamp gap in the CSV file, so I'm inclined to think that the actual frame was not dropped, just the TTL. Most of my 2.5+ hr recordings don't have dropped TTLs.

-Eric

[DCL]

Thank you both!