Getting error adding DCP

Anything and everything to do with DCP-o-matic.
go4shoe
Posts: 5
Joined: Mon Feb 12, 2024 3:52 pm

Getting error adding DCP

Post by go4shoe »

I am trying to add the attached DCP to a project.
I am getting the following error message - Error: Could not find essence type()

Any advice? Thanks.
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carl
Site Admin
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Joined: Thu Nov 14, 2013 2:53 pm

Re: Getting error adding DCP

Post by carl »

There is something wrong with the MXF header in one (or both) of your MXF files so that the asdcplib library cannot find what type it is (JPEG, PCM, timed text etc.).

How did you make the MXFs?
go4shoe
Posts: 5
Joined: Mon Feb 12, 2024 3:52 pm

Re: Getting error adding DCP

Post by go4shoe »

Thanks for the quick response.

I made the DCP package with our software and a customer complained that our package can't be played in DCP-o-matic.

If I add the video and audio MXF files through 'Add file(s)...' I don't get an error message.

Only if I use 'Add DCP...' - I get 'Error: Could not find essence type()'
carl
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Re: Getting error adding DCP

Post by carl »

Adding the MXFs separately will miss out some checks.

Does the DCP play on a DCI projector?
go4shoe
Posts: 5
Joined: Mon Feb 12, 2024 3:52 pm

Re: Getting error adding DCP

Post by go4shoe »

I don't have an information about playback on DCI projectors.

Where in the source code is 'Error: Could not find essence type()' generated?
carl
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Re: Getting error adding DCP

Post by carl »

It happens because this method in asdcplib does not return `RESULT_OK`
go4shoe
Posts: 5
Joined: Mon Feb 12, 2024 3:52 pm

Re: Getting error adding DCP

Post by go4shoe »

There is a bug in your code.

libdcp/src/asset_factory.cc line 65:

if (result != ASDCP::RESULT_OK) {

should be

if ( ASDCP_SUCCESS(result) == false) {

'ASDCP::EssenceType' may return RESULT_FALSE which is KM_DECLARE_RESULT(FALSE,1, "Successful but not true.");

This happens for example when the MXF header is missing an optional value - then ASDCP returns RESULT_FALSE - since no check was performed.

Please consider fixing it.
carl
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Re: Getting error adding DCP

Post by carl »

I'll take a look, but the library relies on finding the type of MXF this way so it might be a bit involved. Given that I don't remember seeing this error before I wouldn't be surprised if other systems also had difficulty when this value is missing.
go4shoe
Posts: 5
Joined: Mon Feb 12, 2024 3:52 pm

Re: Getting error adding DCP

Post by go4shoe »

The way ASDCP's checks work: The last positive return code is returned (or error)

If the last check happens to be a missing optional value - then you get OK_FALSE = 1

My DCPs are missing an optional value that is checked last in ASDCP.

If you browse through ASDCP's source code - almost always they use ASDCP_SUCCESS(result) and not result != ASDCP::RESULT_OK.

If you want I can submit a pull request.
carl
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Re: Getting error adding DCP

Post by carl »

Ah right I see what you mean, sorry. I thought the main picture/sound essence types were not being set. I'll fix the check.