Why capture HDV via HDMI?
Visual frame accuracy, picture quality, and recapturability are only some of the many advantages of HDMI capture.
By Allan Tépper | January 05, 2009
For many reasons explained in my recent article, it makes a lot of sense to capture your HDV footage directly to an editing i-frame cÃ³dec like ProRes422. One of the best way to do that nowadays from HDV is via HDMI. Editing directly from ProRes422 files (as opposed to hybrid editing or native editing, as explained in the prior article,) offers you visually frame-accurate editing, which is critical whenever your project includes:
- Critical multilayer editing
- Independently recorded 48 KHz audio which needs to be lip-synced
If you try to do either of those two things from your raw long-GOP HDV footage directly, you'll find that what you see is rarely what you eventually get. This has nothing to do with choosing to shoot in HDV or not; but it has everything to do with how to post-produce your HDV footage, especially when your production will include either of those two demanding facets mentioned above. (If your production includes neither of those facets, and you are very short on space, then hybrid editing or native editing would work, but you would miss out on some of the other advantages you're about to discover.)
Advantages of capturing via HDMI directly (or via HD-SDI) as opposed to other methods include:
- Avoiding unnecessary D>A (digital>analog) and A>D (analog>digital) conversions by keeping your HD signal as digital (as opposed to capturing via component analog). Click here to see a breathtaking comparison video, courtesy of Convergent Design and JVC Italy. The same HDV 720p25 footage was captured from the same HDV tape both via component analog HD and via HDMI>HD-SDI, and compared. This video is in 1280x720 in WMV. If you are on a Mac and have not done so yet, please download Flip4Mac's free WMV component for QuickTime here, which will allow you to see WMV in your QuickTime Player.
- Taking advantage of the HDV deck's correction circuit (which is unfortunately bypassed via IEEE-1394).
- You can get a more universal HDV player (see details later in the next article, Universal HDV deck, coming January 8th).
- You can save time and space (as opposed to capturing via 1394 and converting later)
- You retain Log & Capture, deck control, original timecode, and (as a result) recapture capability (as opposed to using FCP's HDV-ProRes422 capture preset via 1394, where you sadly lose all of these four features)
In case you didn't know, the HDMI interface was designed to transport uncompressed digital video signals (both standard definition video and full-raster high definition video, either at 1280x720 or at 1920x1080), with optional digital audio. With those features and quality, HDMI rivals both SDI and HD-SDI in many applications. There are differences, but few.
A few years ago, we saw HDMI outputs start appearing on certain DVD players and HDV decks, like JVC's BR-HD50â¦ and more recently on some of Sony's HVR series HDV decks. Several HD camcorder manufacturers have added HDMI outputs, including Canon (consumer only... so far), JVC (consumer only... so far), Panasonic (consumer & professional), and Sony (consumer & professional). Also, several non-linear hardware manufacturers have added an HDMI output for monitoring. At the beginning, these HDMI outputs were destined to be connected exclusively to HDMI monitors, since no video production or post-production device had an HDMI input, until... (see page 2!)
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