ALE adapter round-trip CDL Values

[reinecke]

Feature Request

New feature

Description

The ALE adapter reads CDL values into the cdl namespaces of clip metadata dictionaries from the ASC_SAT and ASC_SOP fields, however it does not write them back out. It would be helpful to have the ALE adapter round-trip this data. This would also match the EDL adapter behavior.

Context

For how the adapter reads CDL values, look here. For an example of how the EDL adapter writes out this metadata, look here

[Viraj-Rana008]

@reinecke I want to work on this enhancement. So what we need is to append the ASC_SAT and ASC_SOP values in the line list (of _parse_data_line function). In the same format as done in the EDL adapter. Right?

[reinecke]

Hi @Viraj-Rana008 Thanks for your interest! I'd look at the write_to_string function in the adapter.

Note that at the moment, the adapter builds a list of columns that are in the ALE metadata to determine what to output, it also gathers some "special" column names that it will always output.

My approach would be to add some code to detect if the cdl key is present in the clip metadata and add ASC_SOP and ASC_SAT columns if at least one of the clips has it. Then, in val_for_column, I would add handling for generating the ale formatted versions of those.

In the unittests, sample_cdl.ale is a good example of how ALE formats those fields.

Additional note: sample_cdl.ale has a CDL column in it. I'm not sure what software generates that, all the CDL examples I have on-hand use the ASC_SOP and ASC_SAT columns. I see in the parsing code that any values in CDL are overridden with values from ASC_SOP and ASC_SAT - this implies that ASC_SOP and ASC_SAT are considered to be the source of truth. I think the best idea for us when writing is to adhere to the ASC_SOP and ASC_SAT columns. If someone has a use case for writing a CDL column, we can consider that as a separate request.