Re: curious... AVC vs. AVCHD?

It's all about the standards.

"AVC" means Advanced Video Coding... this is also known as H.264, also known as MPEG-4 Part 10. That's just the video standard, without many bounds on it.

When you select an AVC render, you have a bunch of control over things, but also, some concern about compatibility. Video doesn't just live by itself on a computer or most media players, it needs to be put in a "file wrapper" and probably multiplexed with audio. Classic computer versions of such wrappers are the Windows AVI file formats or Apple's quicktime format. For AVC, the typical file wrappers are derived from the MPEG set of standards. These include the MPEG-2 Transport Stream (.ts, .m2t, and .m2ts files) and the MPEG-4 file wrapper (.mp4). You can select a number of these when you do an AVC render. Or you can simply render a "raw" AVC elemental stream, which doesn't allow any audio to be multiplexed.

AVCHD is a standard that includes AVC, but other things as well. It was originally a simplified version of the Blu-ray standard, to enable DVD and BD-based camcorders, and today it's of course the most popular camcorder format for consumers (there are a few pro versions as well, such as Panasonic's AVCCAM). AVCHD specifies AVC bitrates (up to 18Mb/s for video on DVD/BD, up to 24Mb/s for flash-card based video, and up to 28Mb/s for 1080/60p video under the AVCHD 2.0 spec). It also specified MPEG-2 Transport Stream as the only file wrapper, and AC-3 audio as the only audio format. And the Blu-ray derived directory structure, things like that.

So your choice for rendering depends on what it's for. Vegas has templates for "generic" AVC oriented toward various things (online, devices, Blu-ray, etc), as well as standards-compliant AVCHD options.

-Dave