What video files are most suitable for the timeline? I realize if you have only a single core cpu (as I do) you should make sure to not use too high a resolution but what about Codecs.
Is a video file encoded with mjeg the best for editing in? or .DV or .mpeg2 and what are to be avoided .flv I suppose

The native files off the camera or source. Although I have faster machines, I generally end up using an old Sempron, from memory the lowest speed that offered 64bit OS at the time and 4GB RAM. Low power machine but I use proxies for HDV & Canon T2i / 550D h264.

Have you considered kdenlives proxies, specifically created to allow editing on older machines and or with heavy codecs?

Many NLE's don't offer a proxy workflow within the app? The work around has been to transcode to a less demanding codec and accept whatever quality loss and/or have some kind of automated proxy swap, file remapping scripts or an EDL of some description.

Thanks for the info - never tried proxies yet but will look into it I read this page
http://wiki.treet.tv/Intermediate_Codecs
and it seems DnxHD is good but would be too much for my machine.
ffmpeg supports is so I guess i could try lower bit rates?
ffmpeg -i -vcodec dnxhd -b -an output.mov).

It's just that I have some family vids that could do with editing but were taken a long time ago and they are in mpg form -also sometimes I take vids from internet in .flv form and wonder what I should convert them too for better editing on the timeline

Hi NorthernB, I just wanted to say that I have been using AVCHD files for about a year now with no problems whatsoever. This is, of course, as long as you use Proxies. These just make a low resolution copy of your clips for smoother use in the timeline and monitor. Cut an chop whatever you like but when you render, Kdenlive uses the original AVCHD files.

This does depend on a newish version of Kdenlive etc. which most people are using. Any other problems with these files, just ask, someone might be able to help you.

Rendering artifacts and seeking issues. Is this related to interlaced h264 in an MTS?