HDMI in HDV and AVCHD Camcorders
 

We just published a white paper on HDMI technology found in the HDV and AVCHD camcorders and decks. See www.convergent-design.com

Mike Schell
Convergent Design

Thanks Mike - interesting stuff. I've a question: how do you connect the HD-Connect MI with a PC? I read it's a coaxial cable hooked up to the HD/SD-SDI BNC, but which PC port does it go to? Some special capture card?

Hi Piotr-
You'll need an HD-SDI capture card. Blackmagic Design or AJA make these sorts of cards.

Best-
Mike

If so, please explain to me what's the point in spending $6xx on the HD-Connect MI PLUS another $1000 on a HD SDI capture card, when I can feed HDMI directly using the $249 Intensity card? What are the advantages that cost so much?

TIA

Piotr

HD/SDI has advantages over HDMI, notably integration with practically all high-end equipment (monitors, capture cards, decks, you name it) and, on a more practical level, BNC connections which ensure the cable stays connected during camera moves etc. With HDMI you'll need to do the old "rubber-band round your camera tied to the connector" routine, like with FireWire...

In terms of signal quality, as far as I'm aware, no difference (well, that's not strictly speaking true, HD/SDI will, I believe do 10-bit as opposed to HDMI's max of 8 bits - is that right? - plus you can use dual-HD/SDI to transport 4:4:4 1920x1080 HD, for instance to an HDCamSR Deck, which you can't do with HDMI). But as far as 1440x1080 4:2:2 8-bit, I believe they are identical.

Not sure about HDMI when it comes to TC sync, Genlock, SMPTE and that sort of stuff - Mike (or anyone else!), any info to impart on that?

So basically, for Indie's HDMI is a much cheaper solution, but the pros will want HD/SDI to fit into their current workflow, ensure their expensive kit is not redundant and, possibly to allow for higher quality capture for chroma-key work and VFX.

1440x1080 4:2:2 @ 8-bit still rocks a load though, and it's also worth noting that quality-wise, if you're going from an HDMI source, conversion to HD/SDI will certainly not bring any image benefits - a lot of the benefits I stated above are true only for native HD/SDI systems...

Unless I am mistaken, HDMI 1.3 supports 4:2:2 and 4:4:4 RGB or YCbCr at 8, 10, 12, and 16 bits, and up to 1080p60 at 12 bits. Because the 1.3 spec was released only in June, it seems unlikely that's the version Sony supports in the V1.

The HD-SDI stream from the HD-Connect MI box is actually 1920x1080i 4:2:2. The 1440 line length is automatically upsampled before being output from the HDV deck / camcorder. (While the HD-SDI stream is actaully 10-bits, you only get 8-bits of effective resolution). The HD-SDI stream will include embedded audio and time-code, so you can easily make dubs to HDCAM decks. The box does not include genlock, but you don't need this feature for dubbing or ingest into an NLE.

The HD-Connect MI box is a great solution for existing HD/SD-SDI based users (Avid, Final Cut Pro, Quantel, Media100, etc) as it is a simple solution and you don't have to install drivers and deal with any potential conficts in your system.

The other compelling application is live capture of never-compressed video straight from your camera. The long length of the HD-SDI cable means you don't have to drag your deck or NLE system next to the camera.

Mike Schell

Hi Lawrence-
You are correct, the latest HDMI spec does support "deep color" as well as greater bandwidth. But from the point of view of existing HDV and AVCHD cameras, the best you'll get is 1920x1080i YCbCr 4:2:2 8-bit, which is actually transmitted over HD-SDI at 10-bit resolution, but the lower 2 bits are set to zero.

Mike Schell
Convergent Design

One point that is in favor of the HDMI flavor is that the cost of a HD HDMI capable monitor is a lot lower than a HD SDI monitor. Cabling is an issue with HDMI but INTELIX for instance now has a HDMI over Cat5 solution.

Certainly an argument could be made that HD SDI is going to get you a more pro setup, and Mike as done a good job of outlining the advantages, I think the hdmi solution might get you close in terms of some features, but with a much lower entry price point. Connecting a AVCHD or HDV camcorder with HDMI to a consumer HDMI display and say a BlackMagic Intensity card is probably going to be a much more economical solution. IF you are looking for timecode, and deck control or interfacing with a HD SDI switcher, then HD SDI is probably the way to go. Panasonic looks ready to release a 5 HD SDI/ 1 DVI live switcher for about 8 thousand dollars, so if the HD SDI monitor issue could be resolved the balance could be shifted back to HD SDI from a cost standpoint.

Sharyn

Likely the idea of a $6000 product came long before anyone thought of a $250 card. And, such a card could be made as a ExpressCard for laptops.

While there will be some who care about recording direct from the camcorder -- the vast majority of HDMI use will be in post.

Two questions.

First, is RGB (which is limited to 8-bits) or YCrCb (which can support 10-bits) commonly used?

Second, since this is a V1 forum, if HDMI is only 1920x1080, why would Sony down res to 1440x1080 then up res to 1920x1080 for HDMI, as some people here have claimed?

Is RGB/YcRcB commonly used for...?

The HDMI out occurs BEFORE the HDV compression stage, but after the "resolution reduction" from 1920x1080p to 1440x1080. This part of the signal processing. Why this was done, I don't have an explanation. But this is how Sony is doing it. I'd assume it's because it's post DSP but pre-compression.

HDMI is not ONLY 1920x1080. It carries any digital resolution or frame-rate.

Are TVs, Camcorders, DVRs RGB or YCrCb?

So where do they up res it? The reduction is a separate module from the image processing (according to the Sony block diagram).

P.S.
AJA doesn't have an HDMI card. Other than Black Magic, are there any HDMI imput cards?