I Need AVCHD Editing Information

[Satchmo]

Let me start by saying I have indeed spent a lot of time looking over the guides here at videohelp. I never cease to be amazed by the amount of talent and willingness to share techniques displayed here. The best resource I have encountered for video editing etc.

Okay, there are few things I don't understand about edtiing AVCHD. First example; my daughter's Insignia NS-DCC5HB09 camcorder footage. This little pocket camcorder serves up avi wrappers with some version of AVCHD file inside of it. It records an amazing amount of hours on a SDHC card. Even at full resolution which is HD(allegedly). She needed to make a five minute video for a school project. She shot about six minutes of video and proceeded to try to do some editing in Windows Movie Maker. Long story short, of course it didn't work. After a LOT of googling, I found a simple tutorial that suggested using Google's Picassa moive mode to transcode the files to wmv so WMM would edit them. It worked but two things stood out. It toook about twentyfive totatl minutes to convert the files. A 4-1 time disadvantage. The files were also double the size of the raw footage files. As you might imagine, I was asking myself why all this fuss and work to edit FIVE STINKING MINUTES OF VIDEO? In a lossier format than the original to boot. And then she still had the time used for joining the clips. Insane.

Questions. Why do I see AVCHD referred to almost exclusively as a "delivery format, not an edting format". Doesn't someone have to edit whatever material is delivered no matter what media it is presented on? I guess I am asking why the need for tonnes of hours of transcoding and possibly re-encoding just to join together a half dozen one minute clips? Is this a deficiency of editing applications or hardware related or both? BTW, my machine features XP 2002 MCE (SP3), 1Gb ram, 2.8 P4. Hardly a powerhouse. I don't mind buying an editor but from what little I can glean from the forums, even some of the pricey NLE apps don't import or export this format very well. And they need horsepower too. This is pertinent for me since my wife and I are going to buy a flash camcorder and wonder if we should be paying close attention to the format and container it uses. Sorry to be so long and I am sure this topic has been covered but I couldn't find a real close match in the search. Thanks.

PS: When I said I don't mind buying and editor I was not really referring to something like one of the pro editors from Adobe like CS4. A thousand plus for my home use is not in the works. I am thinking more in the <150 range if that is possible.

[guns1inger]

A delivery format usually means one that uses heavy temporal compression, long GOPs, and is designed for playback first and foremost. It usually doesn't survive repeated encodes very well, quickly showing artefacts and quality loss. Basically, cameras that use AVCHD for recording do so because it is very space efficient, and because (rightly or wrongly) the camera manufacturers do not expect end users of these camera to do much, if any, editing.

If you do want to edit, you need a fast machine and an editor capable of working with the footage, and very few, if any, can edit it without re-encoding the full the thing (The new videoredo beta can do this, but only does trims, and is not an NLE). Some cameras come with their own application. While not fully featured, they do have the advantage of working with that camera's particular flavour of AVCHD. One AVCHD is not like the next, and not all forms can be read by all editors.

The last good format for editing for the consumer was DV, followed by HDV (high bitrate mpeg-2) when edited with an mpeg-2 aware editor.

[redwudz]

It's correct that AVCHD is not good for editing, as most other highly compressed formats are not. You've found one alternative, convert the format to one easier to edit. To do that quickly, you need a fast computer, preferably multi-core. One problem with highly compressed formats is the spacing of the keyframes. And you normally have to make your cuts on the keyframes to avoid sync and picture breakup problems.

A keyframe or more properly, 'I' frame, is a complete frame of video. The others in between are just partial frames of the difference from the nearest keyframe. That's one way they achieve high compression. With Divx/Xvid, keyframes are about 300 frames apart. Most highly compressed video is similar. That makes frame accurate editing very difficult. Converting to a lossless format like Lagarith or HuffyUV is one alternative as all frames are keyframes. The downside is huge files, on the order of 25GB or more per hour of video. You would need a lot of hard drive space. There are other alternative codecs, but they aren't freeware. And they still need a fast computer and lots of HDD space.

Sorry, there is no easy answer.

[Satchmo]

Thanks guys. I figured it had something to do with the amount of compression but since I am very green with video edting, I hadn't a clue about the key frame spacing. Hopefully the situation will become easier before too many years go by. It seems as if AVCHD of one flavour or another is becoming the norm for flash memory camcorders.