Is AVCHD useful?

You may have noticed this ad on my sidebar for the Sony HD-RTG1.  I hand picked that ad because it seemed like a great semi-pro video camera.  It is reasonably priced, records HD video to a memory stick, and is small enough to fit in your pocket.  It might not be as professional as a higher end camera, but it seems like a good backup camera or b-camera.  Rob Kelly used it on a recent realty shoot to get extra footage.  The size and convenience makes it perfect to get shots that would otherwise be missed.

The video file format is AVCHD. How does that fit into a pro video producer/editor’s workflow?  It seems to be becoming the consumer format of choice for all the new cameras.  How do we deal with this footage?

On a recent outing Rob shot some footage for me with his HD-RTG1. The clips created have a .MTS extension.  With other video cameras you end up with a folder full of .AVI or .mpg clips.  But with AVCHD cameras you get an entire BDMV folder structure that looks suspiciously similar to that of a BluRay disc.  Just in case I needed it, I copied the whole directory structure to my drive. (well, mostly)

Lets define the rules of the game:

• First off, and I don’t care if you disagree, professional video editing is done on a Mac, not Windows. So to be a useful format there needs to be a way on the Mac of either accessing the clips directly or converting them to work in Final Cut (or Avid).
• Second, it is acceptable to use one format as an acquisition format and another as an editing format. When your source format is highly compressed like h.264 it is basically a requirement that you transcode to a better format for editing.  H.264 is not good for that.  The editing format needs to be high quality to intermix with other professional video sources.  Apple ProRes 422 HQ is a very good, high bandwidth, full 1920×1080 format.  This is my format of choice.  FYI – it does require an intel mac.  The best scenario for retaining quality throughout post is to convert all sources to your editing format prior to editing. By the way, DON’T allow FCP or Avid to convert footage on the fly.  And DON’T use footage in your timeline that has to be rendered to play natively.  This puts too much trust in the default scaler/converter which usually sucks.  It will make your footage look like poo.
• Third, we’re looking for the fastest, most convenient, highest quality converter available. But it also has to be reasonably priced.
• Last, the converter can’t require that we have the camera because we might not always have that camera. Archival of the footage is going to be the original source .MTS files not the converted files which would be much much larger. We need the flexibility and longevity to be able to convert footage whenever we need, even if its after we’ve sold the camera.  Otherwise the file format could become obsolete and worthless.

A Google search revealed that several people have been asking “how do I use this footage.”  One popular response was to burn the BDMV folder to a BluRay disc.  While it’s very cool that this works, that plan is only worthwhile for a consumer who wants to watch home movies.  It’s doesn’t help us use the footage to edit.  Another response had something to do with Nero or some windows crap that is totally irrelevant according to rules 1 and 3.  It’s too annoying to have to load virtual PC to convert the footage, and windows can’t create a ProRes file.  This would mean having to convert the footage twice = NO.

The most popular advice given was to import the footage directly into either iMovie or Final Cut Pro. Skipping iMovie for obvious reasons I’ll focus on Final Cut Pro.  FCP supposedly ingests AVCHD footage via the Log and Transfer tool and converts the footage into either AIC or ProRes. The FCP HD and Broadcast Formats manual suggests that it can take the footage off the camera or off a hard drive as long as you copy the entire file structure.  So far I have not been able to get it to work.  This is possibly because of how I copied the files off the memory stick. Rob’s camera had about a hundred other clips on it that I didn’t want. I only copied off the clips from my shoot. My guestimation is that either the INDEX.BDM file or the PLAYLIST file points to his other footage which I didn’t copy.  FCP interprets the missing files as an invalid directory structure.  At this point I’m not sure what the work around is for that.

What about other methods of accessing or converting the file?  There are two other programs to take a look at.  First, Voltaic is a rather bare bones mac program that converts AVCHD footage to a quicktime file.  It has a batch mode, shows a thumbnail of the clip and some info, and gets the job done for about $35.  The downside is that it’s slow.  My 25 second clip took about 5 minutes to convert on a 2.33 GHz MacBook Pro.  The upside is that you don’t need any of the extra file structure that FCP requires.  Just drag in the .MTS files and you’re good to go.  By default it converted my file to an AIC codec, but under Preferences there is a Use Advanced Export Setting button that will allow you to pick from a large list of formats including Apple ProRes (if you have it installed), and the Elgato Turbo.264 codecs which is good for making footage review copies.

The second program to consider is VLC. VLC will play the MTS files but does not recognize them when you drag and drop then on the icon.  You first have to launch the program, then go to File>Open File… then pick the .MTS file manually.  VLC is free but is a video player and not a converter.  However it can be useful to quickly browse your MTS files since it decodes them for playback in real time.

My conclusion about AVCHD is that it’s similar to the early days of HDV.  I expect that all these bugs will eventually be worked out.  Hopefully Apple will fix Final Cut’s Log and Transfer mode so that it doesn’t require all the extra file structure.  And while the file conversion is a slow process and a bit of a hassle, at least there is a process that works.

Here are some things to keep in mind about using AVCHD in a post production workflow:

• AVCHD is an acquisition format.  Consider it as your source footage.  You can’t edit in that codec or finalize back to that codec.  Your edited master should be a much higher quality codec.
• AVCHD is very highly compressed.  Remember this is HD video compressed down to the 12 – 17 Mbps range.  Compare that to BluRay which has a similar codec and is more in the 25 – 35 Mbps range. Another quality consideration is that lower end AVCHD cameras record at 1440×1080 rather than 1920×1080.  Unfortunately so do many other HD acquisition formats, such as HDCAM.
• The transcoded video files will take up much more hard drive space than the AVCHD files. AVCHD is variable bit rate and therefore it’s difficult to know exactly how much larger the file will be.  An easy quick estimate is 10 times the space but it could be as much as 20 times.
• AVCHD support requires an Intel Mac Pro.  Same goes for Apple ProRes.  But we’re in the ‘out with the old, in with the new’ mode these days.  It’s time to sell off all the old gear and buy new stuff.
• For now, it’s best to copy the entire file structure off the memory stick and not just the .MTS files.
• This technology is new, so expect a few bumps in the process for the next year or so.

To me, the whole point of tapeless is that you get much faster access to the footage.  Copy it over via USB2.0  and start editing right away. With AVCHD the footage has to be converted to be useful, which for now, takes MUCH longer than it would take to just capture the footage in off tape.  Capture is real time - conversion take 5 to 10 times as long. Archival is also an issue.  With taped acquisition you have a built in archive – the tape.  With tapeless you have to work out the archival for yourself.  Think that through and don’t mess it up.  You don’t want to be one hard drive head crash away from losing everything.