What is AVCHD?

AVCHD is yet another video format for recording movies on a camcorder. Just when you thought you'd got a handle on all the abbreviations and acronyms in the world of video and HDTV, Sony and Panasonic roll up with another one.

However, this time, there's a very good reason. Until now, HD camcorders, such as Sony's HDR-HC1 and HDR-HC3 have had to make do with relatively inefficient encoding algorithms for recording and storing video. As these camcorders stream video to tape and the video streams at the same rate as DV video, this hasn't been too much of a problem. But tape, thankfully, is declining rapidly in popularity as a format for video, and is being gradually replaced by DVD, flash media, and, best of all, hard disk. These media store footage differently and DVD and flash media in particular have very limited capacities. Thus, there was a need to come up with a way of encoding video that allowed it to be reasonably highly compressed without losing quality. Step forward AVCHD.

The good news is that it is based on existing standards, namely a variant MPEG-4 known as H.264. The H.264 format will be used in Blu-ray and HD-DVD discs, and in European HDTV broadcasts (US HDTV broadcasts use MPEG-2, the same as regular DVD). It's also supported by Apple's QuickTime software.

AVCHD will allow up to an hour of high definition video to be stored on dual-layer 8cm DVD discs at the standard quality setting, although only 15 minutes at high quality. The Sony HDR-SDR1's hard drive can hold four hours at high quality and eleven hours at standard quality.

The bad news is that there's currently no software available for editing AVCHD, although Adobe, Sonic, and Ulead have all said they will support the format. Apple, as is its habit, is silent on the issue.

Then there's playback. You can hook up a camcorder to your TV and play content back directly, but current DVD players won't play DVD discs recorded in an AVCHD camcorder. Sony says that its forthcoming PlayStation 3 and Blu-ray players will play the discs. And its likely that manufacturers of DVD players will license the software to enable third devices to play back the new format too.