Panasonic’s AVC-intra codec

I’ve been hearing a lot about Panasonic’s new AVC-intra codec lately. It promises to deliver pro-quality HD at smaller file sizes, and uses intra-frame compression (as opposed to inter-frame compression formats such as MPEG-4).
Here are my thoughts on the subject. The intra-frame compression is a definite plus. Whilst working with MPEG-4 compressed footage on The Toilet Guy…, within about 6 months, the files (stored on removable hard disks) had suffered severe corruption. It wasn’t just one or two frames that were affected, it was several seconds. And in some cases the problems weren’t immediately visible, there were sync problems and dropped frames, spurious freeze frames and so on. Not good at all. But even in those cases, there was always the original camera tape to fall back on (way more robust in the long-term). Now Panasonic has been pushing for a tapeless workflow for a long time, but this format is the first instance where they seem to be thinking seriously about the challenges involved in doing so.

There are still other issues to address, such as image quality. I’ve heard that some test footage shot with the HPX3000 camera is looking pretty good. It’s still shy of the Viper camera though, there is no talk about log colour space for example, and it’s got 4:2:2 compression in addition to the H.264 compression as part of the format. The AVC-intra 100 format will also record the full 1920×1080 progressive frame, so you would expect that the resolution is good. All in all, the format has a data-rate of 1GB/min (or 60GB/hour if you prefer).

That’s very reasonable, until you realise you have to store it all on Panasonic’s crappy P2 cards (at least for the duration of the recording).  When I say “crappy”, I mean expensive and small. A single 16GB card will set you back $1000. Yes they are solid state, and they are reusable, but there is no way you will be using them like camera mags, shooting and shelving them, unless you’ve really got a disposable budget* (think about it, that’s $60 per minute of rushes), and even then, there are better ways to protect your data.

You can daisy-chain up to 5 of them together, which will give you up to 80 minutes of sustained shooting. But at some point you’ll have to give them to someone to plug into a laptop and copy onto long-term storage. So in reality, the 10 or so P2 cards you buy are just glorified buffers between the camera and the hard disk.

So the question for me is, if you’re copying them to hard disk (or data tape) anyway, why not uncompress it to a frame-based format such as DPX or Tiff, given that you’re probably going to have to do this at some point to do a DI or online? As of yet, there is no professional grading system that will conform from AVC-intra files as far as I’m aware, and certainly no reliable way to batch convert select frames from movie files by EDL. And if you’re converting to a frame-based format, then ultimately what advantage does AVC-intra offer over any other compression format?

Now I realised I’ve presented a somewhat twisted argument here. Ideally what I’d like to know is how robust the format is if you keep it in its native format for as long as possible. There would be definite advantages to doing so, not least the savings in storage and bandwidth, but would there ultimately be more headaches in the long-run? After all the DPX/Viper workflow of having uncompressed, single-frame files, though not perfect, is a proven one. Can the same be said for AVC-intra?

*Having said that, I have heard of some productions who are doing just that, rationalizing that the cost is comparable to film stock+processing.

Posted: November 7th, 2007
Categories: Opinion
Tags: , , , , , ,
Comment from Phil - 11/28/2007 at 1:25 pm

OK. So now we’re on 32GB cards and soon 64GB (nov 07). That makes them just as effective, if not more so than tapes as you are allready in a file format on a P2 card and save the many hours at realtime ingest rates. I think P2 came out too soon and I agree – what use was a 4GB P2 card? This has poisoned many users away from P2 and rightly so – it’s dammed expensive using 16GB cards compared to tape.
The viper is a designed for the kind of DI process you describe, the Panasonic 3000 is not. I think the 3000 is aimed at the news market just as much as it is anything else, so that’s an SDI and 4:2:2 workflow for most, putting P2 into the mix really does speed up the workflow for studios using a 3000 or 2100 camera from panasonic and P2/AVC I. In ingest time alone those cards will pay for themselves within the first 6 months. Just image using a viper for shooting news and then having to move all those frames in a log colorspace around a news studio – you would be just as much out of your element.
The fact that native AVC 1920×1080 is so close to 2K is the motivating factor for many who choose this lower budget format for documentary and fiction. This causes of course a lot of headaches with regards traditional DI software, colorspace, image conversion etc.
If you do find a piece of software that can convert AVC Intra into DPX files at the full 10 bits, then I would really like to hear about it, as I do believe that the 3000 camera and AVC will be used for this type of work until the newer digital cinema cameras like RED and SI2K become more available to everybody.

Comment from Jack - 11/28/2007 at 4:07 pm

I don’t know of anything specific for doing conversions from AVC Intra, but assuming AVC Intra files can be read by QuickTime Pro, then it should be possible (perhaps by using the Glue tools DPX filter… I mentioned yesterday

Comment from Phil - 11/29/2007 at 7:36 am

Hi Jack,

I’m working in Windows and using SCRATCH. So we’re currently using a AJ-HPM100 and grabbing AVC via SDI with a Bluefish 444 direct to DPX.
Quicktime did come with an AVC Intra codec and the MAC boys use Glue Tools.
Iv’e not yet found a software conversion tool for windows yet, but maybe there’s a workflow with quicktime files and SCRATCH?

Comment from Jack - 11/29/2007 at 9:50 am

Yeah, you should be able to just load the Quicktimes directly into Scratch. From there you can re-export it as DPX

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