Hi

For all those who have Camcorders producing 1080i 50 fps mp4 files.

I use Handbreak to convert 1080i 50fps to 1080p 25fps (de-interlace in "picture settings") using h264 codec.

These pre-formated video files work very well with Kdenlive.

It is my understanding that Blueray works with 25fps. Anyway I could not notice any quality loss. The results are equal to the original.

cheers from OZ

As far as I know Blu Ray specs don't include 25p but only 24p (1080/720), 50/60i (1080i), 50/60p (720p). Please someone correct me if I'm wrong. So, if your mp4 (H.264?) files are hard to edit in Kdenlive and you plan to do heavy color correction/compositing/ecc. and want to lose less quality you should try a first transcode to DNxHD.
Anyway, If you're happy with your workflow I think it's ok. I too use Handbrake a lot (at the end of my workflow) because it's very good, fast and has a very good "decomb" algorithm (a modified port of YADIF which deinterlaces only the fields that need it).
Cheers
Ignazio (from Italy)