[FFmpeg-user] MP4 from MXP - Material Package Only

[DeBacker, Bart]

We are currently using ffmpeg to extract a lower resolution MP4 file from our MXF OP1A standard hi-res files. This is the command:

ffmpeg -i hires.mxf  -s 960x540 -preset veryfast  -framerate 29.97 -f mp4 lowres.mp4

This works, except that the proxy is sometimes up to 15 frames longer than what Premiere Pro shows for the hires.  Digging deeper we found that the Source Package start timecode is up to 15 frames ahead of the Materia Package timecode (as shown by MediaInfo).  It seems Premiere Pro, and other tools we use, are looking at the Material Package, but ffmpeg is extracting the entire Source Package.

Is there a way to tell ffmpeg to just extract the Materia Package?  The difference varies so we can’t simply seek 15 frames in each time.  It also seems ffprobe outputs the Material Package timecode, but I am unable to output the Source Package timecode, so we can’t calculate the difference.

Thanks