[Feature]: Add num samples to `ImageSeries` when external mode is used

[h-mayorquin]

What would you like to see added to PyNWB?

@bendichter Here is the time alignment view of Neurosift from an nwbfile that contains an ImageSeries with external video:

It should be noticeable that the information of time duration is missing for the ImageSeries. The reason is that the length can be estimated when there are timestampsor when there is a staring_time, rateand crucially num_samples (data.shape[0]). But here, the later is missing.

It would be great to have this added to the schema. Note that the starting_frame is not enough to determine the number of frames available for a single ImageSeries in external mode.

Weakly related to this other issue where some guidelines were given: https://github.com/NeurodataWithoutBorders/pynwb/issues/1433

Is your feature request related to a problem?

No response

What solution would you like?

Adding num_samples in the schema for this object or modify the data attribute in the case of external series so shape[0] reflects the number of samples.

Do you have any interest in helping implement the feature?

Yes.

Code of Conduct

• [X] I agree to follow this project's Code of Conduct
• [X] Have you checked the Contributing document?
• [X] Have you ensured this change was not already requested?

[oruebel]

I transferred the issue to the schema repo since this issue is about making changes to the schema

[h-mayorquin]

543 same probably