Editing HDV

Posted on by Larry

[ This article was first published in the December, 2007, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]

I have been somewhat vocal in discussing some of the problems in working with HDV. However, there are lots of different opinions on this point. Recently, Iain Anderson gave me permission to reprint this:

I heartily recommend editing HDV footage natively. A number of people have expressed the opinion that long-GOP MPEG footage is inherently hard to work with. It’s not — it’s very much the same as editing with DV, and Unlimited RT works just as well. You certainly don’t need to render every edit.


I recently cut a short film in HDV on a MacBook Pro, and it was a painless experience which produced high quality results. I used FCP6, which did make the process somewhat easier. As the film was part of the 48 Hour Film Project, I had less than a day for editing and delivery to mini DV tape. A shame to see all the HD quality disappear at the end, but the process worked well.


The advantages of HDV:


1. No extra hardware needed to import footage. Any machine capable of running the current version of Final Cut Pro can cut HDV. It’s painless to edit, and while effects can take time to render, the vast majority of effects work with Unlimited RT just like SD footage. The only issue I had with rendering was when overlaying several streams of video with feathered cropping.


2. No transcoding needed. You can’t get better quality by recompressing. In fact, you can make it much worse. DVCPRO HD, for NTSC frame rates, uses a different frame size (1280×1080) to HDV (1440×1080). If you have to transcode, ProRes 422 or AIC are better choices.


3. Low data rate. It’s HD with the DV space/data rate requirements of ~13GB an hour, while transcoding at least triples your data rate and space requirements. We’ve just about hit the point where you’ll be able to keep all the HDV you ever shoot permanently online by buying a cheap hard drive every few years.


4. Easier media management. When you capture HDV natively, footage is automatically split into separate files based on when you started each recording session. No more huge files from students capturing files in hour-long blocks and easy deletion of bad footage.


5. Near-instant HD screeners. HDV footage needs no recompression to go onto an HDDVD, and every current Mac can play HD-DVD’s made with DVD Studio Pro burnt to regular DVD discs. This is incredibly powerful; it’s about the only way to deliver HD footage without expensive hardware. You will need to conform HDV footage to do this, however, bringing us to…


The drawbacks of HDV:


1. The 4:2:0 colors. Not ideal, but the same as PAL DV. If you’ve shot in HDV, the damage has already been done, but it’s really not that bad. The latest Sony XDCAM EX uses the same colour space. This doesn’t have to limit the quality of your colour correction, though — see 3 below.


2. Long conform times when finished. This is an issue only when you’ve finished your edit and need to export back to HDV. The conforming process takes about as long as a slow render, say, a few times real time. If you’re not finishing to HDV, not a problem. While you’re editing, not a problem.


3. Recompressing to HDV can introduce artifacts and is slow. True if you’re colour correcting or applying other filters, but there’s a fantastic solution built in to FCP 6. Choose Sequence Settings, and look under the Render Control tab. Change the render codec to Apple ProRes 422. Specifically for HDV and XDCAM HD/EX, this feature renders effects to ProRes instead of HDV. No quality loss, no extra time spent recompressing during editing.


For Larry Jordan’s (slightly differing) opinion, click here.


But don’t miss Graeme Nattress’s comment on Larry’s page:

[Should you convert HDV to DVCPro HD?] No. Never! Why? Adding compression on top of compression is just bad. DVCproHD is way too compressed. It’s full of artifacts even straight of a varicam. To add that compression on top of HDV just makes a mess.


Answer – edit HDV native – it’s easy on a decent mac, and then just change the compression right at the end of editing to “uncompressed”, do a final render before going out to master tape. Again, you’d never use HDV as a master – even one compression back to HDV looks awful.


Only use DVCproHD if that’s what you shot, or are going back to DVCProHD tape. If you’re recording live from SDI, uncompressed HD, or Photo JPEG 75%, are much superior.

HDV isn’t perfect, but I’m constantly amazed by the quality I get out of my HV 20 for the price and how easy it is to deal with. It’s possible that the poor opinion of HDV PQ in the industry is partly due to the PAL/NTSC divide. Here in Australia, we only have to record 25 frames per second at the same data rate that NTSC models have to record 30 frames. Those 20% extra frames per second might be pushing the compression just a bit too far.

Larry replies: Thanks, Iain, for allowing me to share this.


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