When using tsMuxer and Avidemux the output video of a BD 1080p feature is a vertical strip with everything on either side of the thin strip missing (H.264 stream @ 128x928 pixels).

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Found a work around.

After Avidemux indexes the stream, it will pop up errors about aspect ratio and not being able to open the file. Edit the '.idx' index file for that video in a text editor and enter the correct resolution and fps * 1000 ("Picture : 1920 x 1080 23976 fps"). Reopen the video in Avidemux.