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.MXF OP1a with captions won't transfer to .MP4 with sidecar captions

Forum|Forum|8 months ago
May 27, 2025
5 replies
131 views

Hello Community

I have a lot of MXF OP1a files with embedded 708 captions and I need to convert them to MP4 files with sidecar captions file.

When I do it through Premiere, some files are imported with the captions -it takes a little while to load- and some others without the captions. I know all of them have captions because they have played several times.

I have done it before using only Media Encoder, because it's faster and I have a lot of files. But now it's not creating the sidecar captions file from the embedded captions. I have checked the settings, both in ME and PR, but it doesn't seem to work.

I'm working with Media Encoder 25.2 (Build 141) and Premiere Pro 25.2.3 (Build 4).

My computer is a 11th Gen Intel(R) Core(TM) i7-11700 @ 2.50GHz 2.50 GHz, with 32 Gb or RAM and the GPU is a AMD Radeon Pro W5500 and Intel UHD Graphics 750.

I would really appreciate any help you can give me.

G

gian.delgadoaspiazuAuthor

Participating Frequently

Thank you so much! I figured it out. Media Encoder, and Premiere Pro need a bit of time to completely read the file including the captions. If the read is not complete, it will only export audio and video but no captions file.

Gian Delgado-Aspiazu

TV Producer
Rogers
4 Mt. Bernard Ave. Corner Brook, NL A2H 6T2

gian.delgadoaspiazu@rci.rogers.com
m 709.640.1017
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Stan Jones

Community Expert

@gian.delgadoaspiazu,

Thanks for posting back! This will help someone else.

Stan

G

gian.delgadoaspiazuAuthor

Participating Frequently

I already figured it out. Apparently both Media Encoder and Premiere Pro need some time to "read" the file, and the last thing they do is "read" the captions. If the file is not completely "read" or loaded, it will assume there are no captions in it. Premiere Pro has a progress bar indicating that is still reading the captions; but Media Encoder doesn't.

It would be a good idea to add one, especially for those working with several files at a time, or those like me that archive in a high capacity but slow speed hard drive where captions take even longer to load.

Thanks a lot for your input!

Gian Delgado-Aspiazu

Stan Jones

Community Expert

@gian.delgadoaspiazu,

You appear to have the preference setting for "import embedded captions" correct, otherwise none of them would import. Some not importing is odd. Do the same files always fail?

And I'm assuming that you are doing what Warren suggests and that this works?

Is there a bug reported on the Media Encoder failure?

Stan

Warren Heaton

Community Expert

You should be able to add the MXF to a Premiere Pro Timeline to get the Captions Track from the MXF and then export that as an SRT or other captions sidecar file format (File > Export > Captions).

Export the MP4 as it's own file to the same location as the captions file.

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