kdenlive offers a broard support of audio and video formats.
Here is a list of supported formats:

DV is the standard for traditional low-resolution MiniDV camcorders.
Technicaly, DV is a slightly compressed video and raw sound.
Kdenlive offers a broard DV support:

HDV is a recording format for use in high-definition camcorders.
Technically, HDV offers mpeg2 compressed video with compressed audio.
Kdenlive offers a board support:

AVCHD is a new video format for high-definition tapeless camcorders recording to memory sticks and hard drive.
Technicaly, AVCHD is a complex mpeg4 video stream, referred as MPEG-4 AVC/H.264.

Kdenlive should support AVCHD camcorders, but this is an experimental feature. If you plan buying an AVCHD camcorder, you should try to download non-compressed footage from Internet. Do not invest in an AVCHD camcorder without prior testing using Kdenlive.
Technically, h264 is a highly compressed mpeg4 format. h264 requires a modern single-core or dual-core computer. Kdenlive is able to read and decode h264 interactively using a multithreaded library using two or more cores if needed. Again, multi-core decoding is an experimental feature, which may not work well.
At the present level of Kdenlive, we do not recommend investing in an AVCHD camcorder. If you have the choice, invest in an HDV camcorder.
Tapeless formats support
Kdenlive supports mpeg, avi, mp4 and mov formats and many others.
Audio formats
Kdenlive supports most audio formats for reading, mixing and exporting:
Flash support
Kdenlive can read, edit and export Flash video.
Open standards
Kdenlive supports most open-standards formats: ogg, vorbis and matrovska (experimental).
Non-destructive formats support
Kdenlive offers experimental support for non-destructive audio and video codec, including:
In the next releases, we hope to offer better support for non-destructive formats, including interactive decoding and encoding on dual-core computers. DIRAC and FFMPEG teams work hard to provide working solutions. Stay tuned.
Image formats
Kdenlive includes a powerfull slideshow features to create animated slideshows. Kdenlive can display images using any common image format, including:
A set of predefined export settings
Kdenlive team is aware that choosing the right export settings is sometimes hard. Therefore we provide a set of pre-defined settings to help you: