“Your first mistake is converting m2ts files to m4v. Convert to Apple Intermediate Codec before you edit.”
I agree with Rob, this is probably the conversion where the video gets grainy. After I continue I must clarify that Apple Intermediate Codec is video CODEC, not a video format. So first you need to select a video format (you will not find Apple Intermediate Codec here), lets say Quicktime, then you select the video codec like Apple Intermediate Codec or Photo JPEG (or among many many others). By the way, what dimensions the original m2ts video has?. Is it 720×480? 1280×720?. When you convert the m2ts video you need to select the exact dimensions of the video, if not you will be down-scaling or up-scaling the video. Also, in order to know if the footage is progressive or interlace you can investigate which camcorder was used to record the m2ts and what settings where used. You can also check in your video converter, it should tell you somewhere the dimensions of the footage, field type (progressive or interlace), aspect ratio and frame rate of the orinal video. If you are exporting to DVD, I recommend exporting to MPEG2 DVD (this format is ready for DVD playing).
As for help and resources, you have Videmaker.com forums and Videomakers Plus Membership which give you access to tons of tutorials. There is also CreativeCow.net, Lynda.com, the almighty Google and among others. If you want to learn you need to read a lot, view tons of tutorials, read some more, practices a lot and have fun.
