|Originally Posted by alvinmc|
If you'd indulge a neophyte here...
I've been waiting for a HDD HD camera, and this one seems to be a great first-to-market effort by Sony.
Can you offer a simple layman's explanation of what AVCHD is? I'm concerned about compatability issues (such as Blu-Ray vs HDDVD)
1. are there compatability issues in saving to a PC HDD? In other words, if saved to a computer HDD, and then from there output to a PJ (Infocus 7210 in my case, @ 720p max resolution), would you retain the 1080i resolution? (I guess this presupposes your computer will output @ 1080i, perhaps another subject...)
2. Would I be correct in assuming the only way to convert to a DVD and retain the resolution would be to have an HDDVD burner? (I have an HDDVD player, & not interested in Blu-Ray)
Good questions! Please bear in mind that I'm a signal-processing guy, not a specific expert on codecs and transport formats. With that in mind:
AVCHD stands for "Advanced Video Coding, High Definition". Internally, it uses AVC/H.264/MPEG4 (all the same thing) compression for the video. The multichannel audio stream is compressed and stored using Dolby Digital 5.1 (AC3). Sony and Matsushita (Panasonic) created a new, only slightly different file/transport format for this and decided to call it AVCHD. Very confusing thing to do, in my opinion. The format is only slightly different than other "mainstream" MPEG4 transport formats, and including the codec name as part of the transport stream name is, well, not something I would have done.
Your question #1:
Let's break compatibility down a bit -
(A) Using a Windows box to store/scale/convert/render 1080i AVCHD isn't trivial in the least. It requires pretty much the very latest CPU, RAM, disk and video card technologies to be able to keep up in realtime while still doing all the other things that a Windows box has to do internally. When I say "latest" I do in fact mean CPU's like Intel's dual-core (Conroe) or quad-core (Kentsfield) with FAST DDR2 memory and SATA-3 or SATA 3GB disks. Both ATI and NVIDIA have capable video chipsets now at the high end of their offerings. (note to AMD fanatics - they may have something that will work as well, I just don't know as much about them)
(B) You can either have the PC render the video and output to the native projector format, or use a pass-through if the projector has ability to convert formats internally. Experience shows that using the PC is normally a much higher quality solution, although the conversion yet again adds to the processing load.
(C) There currently aren't any straightforward AVC-compatible players for Windows Media Center, or really any very good ones for HTPC use at all. That will change, but in the meantime one possible (if technically complicated) solution might be to use Elecard's MPEG decoder and H.264 plug-in with someone else's player.
Your question #2:
AVCHD is most directly compatible with Blu-Ray, sorry. Sony packages a utility with the camera that will burn AVCHD directly to standard DVD-format disks that can be played (they claim) in any Blu-Ray player. Using standard DVD media will limit runtime to around 20 minutes for single-layer disks at the highest quality 15Mbps setting. I don't know yet if the utility supports dual-layer DVD media. If so, you can double that to roughly 40 minutes.
Converting to HDDVD may become possible in the future, but it'll be tricky business. Here's why:
(A) HDDVD uses the VC-1 compression "standard". The spec claims compatibility with AVC, but you may run into undiscovered country.
(B) A transcode from AVC to HDDVD-native VC-1 would be the most compatible, but there would be losses since AVC and VC-1 are only cousins, not directly compatible.
These are the facts as I currently know 'em. If anyone has solid info please feel free to correct me.