Splitting and Joining in MPEG-2 ts format problem

[Steev]

I have used Avidemux 2.6.1 and lately 2.6.3 for the most part successfully. I use it to delete the adverts from tv programmes which I like to record. The recorder records in MPEG-2 ts format. Recently Avidemux splits the various sections I want to keep as 'file' and not MPEG-2 ts as it did previously. I have set the output format to 'Mpeg ts muxer (ff)'. When I try to join the files it also comes out as 'file' instead of mpeg-2 ts. I am using Windows 7. Am I missing out on something? What am I doing wrong? Would greatly appreciate and help or advice to get me back on track. Thanks.

[mean]

What does mediainfo say about the generated files ?

[Steev]

Thanks for replying so quickly. The media info about the original file is in media_info1 and for first split part is media_info2. Hope I have given you the right info. Thanks

[Steev]

and media_info2