AVCHD file spanning

The new AVCHD high definition video standard stores video as files rather than tapes. This is very handy for video/asset management, but runs into a problem with very long clips.

With tape based recording, you can just record for as long as the tape goes. For files, as they get large, they have to be split. This is due to underlying limitations with the file system where the clips are saved (i.e. the memory card or hard disk drive on the camera).

You will find that for large AVCHD clips, the camera will split the files at either the 2Gb or 4Gb mark. AVCHD clips are different to other older video standards in that they are very highly compressed. This is achieved by storing a full image (also known as a keyframe or I-frame) only once, then just storing changes from then on, for a large number of frames.

When a file is split there is no keyframe at the start of second (and subsequent) clips. VoltaicHD can convert these subsequent clips, but it may skip a couple of frames as it looks for the first I frame (or keyframe).