Capture HDMI to Portable Hard Drive
 

It would seem that HV20 users would be salivating for a portable hard drive that connected to the camera via HDMI. This way you could capture full HD resolution footage from the camera on the go and without a tape.
Do you think anyone will figure out how to do this?
Would it be prohibitively expensive to make?

Note that it would be uncompressed, not just full resolution (1920x1080), which would mean a LOT of space.
It's not clear yet if the HDMI output is actually pre-HDV compression or other processing (even the 1440 vs 1920 res scaling), so you might not actually gain anything vs firewire, see other threads...

also are other threads earlier about capturing via firewire to drives (works but not perfect as doesn't start/stop w/ button.)

It would be very, very expensive today, think mini-Wafian. The video would have to be compressed somehow though as you'd have to have a crazy multi-drive raid or expensive flash memory array to save uncompressed as far as I know.

The cheap way to go is build/buy a PC and portable-ize it yourself. Probably could build something like that for $1000-$2000.

I searched this forum but didn't find any info about people doing this with the HV20. My guess is that it would work, but maybe somebody could run their HV20 through the paces on this front and let us know.

Sony has a HDD out specifically built for this task that connects via firewire and DOES start/stop with the cam. It records in parallel the tape, and you can even edit right on it. It's NOT cheap though!

http://www.amazon.com/HVR-DR60-Recor.../dp/B000IF9OVS

I have posted about this earlier, but HDMI is nothing more than a fire wire or other digital interface once you have the material on tape. Once on tape the original signal has been heavily compressed and no matter what you do, you can not get back the uncompressed material. IMO HDMI is getting to be a hype for people who do not understand what it is for, same as with 24P, which is also a hype 'to get the filmic look'.

LCD message says "HDMI OUT 1920x1080i"
 

I have the HV20 connected to a projector right now (only 720p) but the PLAY/OUT SETUP2 menu screen says "HDMI OUT 1920x1080i". This suggests that the camera thinks it's uncompressed or "pre-HDV". Maybe it goes from HDV back to 1920 by 1080i for playback, but what about live capture?

Pat

http://www.millcon.nl/Harm/HDMI.jpg

Hope this explains it somewhat.

Harm, I always understood what you just mentioned to be true... the recording on tape is always HDV standard (1440x1080 4:2:0 colorspace) and when feeding that 'recording" through the HDMI output it is blown up to 1980 x 1080..etc.

But ....for "live" feed through the HDMI output to a hard drive the question still remains...is it true 4:2:2 with little to no processing (avoiding the HDV compression)?? I have read several different people's theories on this but nothing conclusive.

I have also read that even with the uprezzed footage from tape through he HDMI the colorspace is somehow at 4:2:2. Some have questioned that and made statements like "how can you get information that was never there to begin with"..etc.

It is sort of confusing for a lot of us when he says this and she says that etc. and to top it off we get no specific information from the manufacturer about this. What I "think" i always understood was HDMI supports 1980x1080 and 4:2:2 colorspace. So I have to believe that is exactly what is being fed through that type of output.

edit: Ok you posted while I was typing. So my question to you is...is it still compressed during a live feed? I have read where others have done their own test and said the colorspace is 4:2:2. How can they get that out of 4:2:0?

By the way...hello ya'll...been lurkin here for a while...sorry for the late introduction.

Ian,

When I made this chart or whatever you want to call it, I wanted to confirm that I was not mistaken or misrepresenting things, so I contacted David Newman, who IMO is one of the most knowledgeable guys around here, and in essence he confirmed this was in general an accurate description of HDMI. He noticed that the data rate I mentioned was too high and should be around 120 MB/s, since the signal from HDMI is only 4:2:2 and not 4:4:4.

Furthermore, David told me that the Sony cameras with HDMI first compress the signal to 1440x1080, then prior to outputting convert it back to 1920x1080 and then put it on the HDMI channel. I do not know about the Canon cameras and how their HDMI works.

I hope I have been relatively clear.

Oh yes you were abundantly clear and the chart was very decriptive thanks. I jumped in this thread because I agreed with keith's statement about users salivating for a portable hard drive to use with HDMI...and I agreed with your peception about peoples lack of understanding (understandably) when it comes to HDMI (me included). My original staement was to feed off both your statements to see if we could get any more information on this camera in particular.
Yeah, I read about how Sony implements their footage through HDMI. And I also thought 200 MBps was kind of high.. 120 with 4:2:2 is what I remember.

Ian,

As you I have often wondered how it could be possible that HDMI does NOT carry a price tag of $ 3.000, which happens to be the main difference between the Canon A1 and G1, and where the difference is the HD-SDI interface and still deliver the same functionality? I just don't get it. It seems like a major USP to me. Still the capabilities of HDMI are the same as HD-SDI in theory. I would be interested to hear practical experiences from users.

It would be worthwhile to have some of the experts here chime in and give their expert opinions, since a lot of people here are anxious to get this cleared up. Does HDMI give out a 4:2:2 signal and how does the up-converting work when starting with a 4:2:0 tape recorded signal?

Much of this discussion is over my head but.... does this mean there might be a potential advantage to capturing video from my HV20 via an HDMI capture card (like Black Magic) as opposed to using firewire?

Besides the fact, that the Cannon G1 offers additional features like genlock capability, the price difference between the A1 and G1 is caused more by product politics than technical requirements. Consumer HDMI ports are cheaper to implement than SDI ports (done with dedicated ICs or FPGAs), but the price difference between both type of interfaces should not exceed $ 600. External HDMI to SDI converters are now available for $ 500.

if the recording via HDMI works it would be possible to record at the same time on tape?
And I ask myself if someone has already buy an intesity card to do some test...

There have been more than one report of the Intensity being incompatible with the HV20 at this time, at least for the 1080i stream.

Would you be so kind to post some link about that?

We've been discussing this over in the Cineform software showcase forum.

If you have any of the HDV camcorders with an HDMI port, you can hook those up live to a card like the BlackMagic Intensity (PCI Express) in a desktop, or a PCI Express enclosure connected to a laptop vie an ExpressCard (http://www.mobl.com/expansion/produc...ressbox1.html).

From here if you have any of the Cineform software packages, you can encode directly to Cineform at data rates the laptop hard drive can handle, in real time.

If you have AspectHD you're stuck with 1440x1080, but if you get NEO HD, ProspectHD and up, you get 1920x1080 10-bit. (Not that the HV20 is outputting 10-bit over the HDMI, but 8-bit uncompressed is nothing to pout about).

EDIT: One should note that this is a solution that is available today. Ideally, BlackMagic will produce the Intensity as an ExpressCard, then the solution will be more portable, and not require an enclosure.

-Steve

4:2:0 is 4:2:2, just alternately "omits" half the chroma "2:2" signal every frame. So a 4:2:0 signal half the time is "4:0:2" and then "4:2:0". A regular system will read a 4:2:0 as 4:2:2 I believe and really see it as something out of the ordinary.

I intend to capture the 4:2:2 video from the Canon HV20 LIVE via Component to my Mac Pro's Decklink HD w/RAID at a very high bitrate (bypassing HDV) - so the same thing as the HDMI capture, but with Component. I'll keep this Forum updated to how it goes, and what I find out.

It was my understanding that Aspect HD could not be used as a live capture solution. When did this change?

A Black Magic Intensity card in an Express Card 34 form would be brilliant!

I agree a Black Magic card in laptop form would be great. But if this can be done, why not go one step further and tie the BLack Magic technology to a portable SATAII hard drive (maybe even two in a RAID config)? It would be much more portable.

I don't know exactly, but check their website: http://cineform.com/products/default.htm
HDMI input from the BlackMagic intensity is supported in their latest round of updates, as is HD-SDI w/o timecode. You have to go to Prospect to get the timecode options.

No slouches those Cineform guys ;)

The problem is that you need about 4 striped hard drives working perfectly to be able sustain uncompressed data rates - so that's pretty heavy duty. If you're willing to accept Cineform as a stellar acquisition format, then you're down to single hard drive bit-rates and an intel Core 2 Duo laptop.

What you really want is a solid state hard drive and Cineform to be embedded in the camera... but we're not there yet for a consumer camcorder.

-Steve

Steve,

Can you provide a link please?

Thanks ...

Sure:
http://www.dvinfo.net/conf/showthread.php?t=88466

-Steve

Has anyone seen this? Announced yesterday.

AJA io HD

io HD + MacBook Pro = portable visually lossless capture on the cheap

hmm... around 1300$ for the hole package? (black magic card, Magma expressbox, magma expresscard) thats to much for me!

Wow. The Aja product looks great.
Another manufacturer should be able to work out a firewire or HDMI connected piece of hardware that has the Cineform Codec built in (instead of the Apple ProRes 422 Codec). I would think a device like that without all the bells & whistles of the AJA product could sell for under $1000. Again, such a product would appeal to the low-budget film producer as well as some in the pro-sumer crowd.

An io HD mini if you will. Leave out the SDI and XLR and sell it for under a grand. Perfect for editing/finishing HDV and AVCHD.

I'd prefer ProRes as I'm a FCP user anyway, as long as it's as good as they're hyping it to be.

I agree! I checked out their site right after my last posting, and am very happy to see that they have added non-firewire injest options(among other things) all at a new lower price point. They have made HQ prosumer HD workable since day one (I started with Premiere 6.5 and ApectHD and a JVC HD10) and now Mac users will soon be able to understand why so many PC users have loved shooting HDV, with support for every cam and frame rate.

As far as what is going out from HV20 HDMI port - 4:2:2 1920 x 1080i or that crippled HDV crap - Just wonder why not to ask directly at Canon? Or they have info embargo on it or what?

We're going to find out sooner or later, hopefully sooner.

1920x1080 to 1440x1080 is the result of that horrible, evil, good for nothing, I can't believe so many people do such amazing work with it, HDV codec. HDMI is a live feed, and in being so is the full 1920x1080 spec as that is what the sensor is, correct?

HDMI can support all kinds of rates and resolutions, as it is backward compatible with DVI-D. In principle, it could be 48 bits per pixel, 1920x1080p @ 120 fps.

In the HV20 and most of the small HDV cams, it seems to go out as 1920x1080 4:2:2 24 bit.

-Steve

Are you suggesting a there is an optional live feed resolution offered by other small HDV cam that is not 720p? I don't know what "most" means, but as long as we are distancing ourselves from that crippled HDV crap it's all good right?! I guess the lighting in Praha is a little hazy?

NOT if you are playing back from tape, then HDMI is nothing more than fire wire, just a digital connection to transfer 4:2:0 at 1440x1080.

I don't think this is quite correct.

HDMI is not a digital data connection like Firewire. Via Firewire you are essentially copying bit-for-bit the data on the miniDV tape encoded in the HDV codec.

HDMI is a digital display connection, and so it is broadcasting uncompressed (or, if playing back from a tape, "de-compressed") footage at the specified 1920x1080 4:2:2 rate. This means that in-camera the video is being decoded from 1440x1080 4:2:0 and up-sampled to 1920x1080 4:2:2. There's no more actual information there, but there is some additional synthesized information. Depending on 4:2:0 artefact reduction circuitry used in the 4:2:2 upsample, there could actually be a boost (or a decrease) in quality attained this way that is hardware specific.

When capturing via HDMI live, you are bypassing the HDV compression and colour decimation to the degree that this is possible out the ass-end of the DSP. If the colour and gamma correction done in the DSP outputs only to 1440x1080 4:2:0 before sending it the MPEG-2 algorithm, you are only saving on the HDV artefacts and GOP structure. Still, uncompressed 1440x1080 4:2:0 is much better than the MPEG-2 followup.

From what I've read, there is evidence that processing is done at full 1920x1080 4:2:2, and that what is broadcast on HDMI live is indeed significantly higher quality than the HDV output. I believe this applies to all the HDV cameras with an HDMI output, but someone would have to do careful case-by-case testing to be sure.

-Steve

It's full resolution uncompressed 4:2:2 full resolution from all HDV cams whether it is HDMI, SDI, or analog Component out. Except for the JVC HD1/10 which is only 480p60 component out. Of course all of these cams are all 8-bit.