Capturing uncompressed HD
 

Hi

I purchased the GY-HD101 a few weeks ago (love it!). I am mostly doing chroma-key work and would therefore appreciate the benefoits of working with an uncompressed signal. Can anyone recommend the least expensive way to capture uncompressed HD from the 101 either to my G5 Mac or 2.8ghz laptop?

Thanks.

Trevor

I just successfully did it last week with a Decklink HD system on a Dual 2.5 G5 equipped with a Decklink Multibridge (for analog to SDI conversion)

It worked great, but you have to remember that you can only get true uncompressed when shooting "live," not playing back from tape (since the signal has already been through the MPEG2 encoder.)

The other thing is that when in 720P30 mode, the analog component outputs send out 720P60. This is great for shooting true HD slow-mo.
When the camera is in 720P24 mode, the output is 720P48. I captured this stream with the 720P60 decklink preset and it had a pulldown of 4:1.
I assume 720P25 can be captured in a 720P50 stream? I didn't test 25P.

Decklink?
 

Hi

Thanks for the reply. A couple of further questions then..

(1) What was involved in the deck link set up and any idea of rough kind of price?

(2) How are you capturing live onto your Mac? I can capture live on my windows laptop using Serious Magic's DV Tack. But I don't htink I have anything to capture live on my Mac. I use Final Cut Pro 5.

Thanks

Trevor

So it captures the 24p fine then? What about the SD modes? Can it capture 480p60?

I was specifically using Decklink HD PRO 4:4:4 ($1495 U.S)
http://www.decklink.com/products/hd/

and the Multibridge HD ($1995 U.S.) to convert the HD anolog out to SDI.
http://www.decklink.com/products/multibridgeconverter/

digitizing to an Xserve RAID ($8000 U.S.)
http://www.apple.com/ca/xserve/raid/

Keep in mind this system is in a post-house, so not the kind of thing you would be able to cart out to location to record uncompressed HD. The only really useful application would be clean green-screen shooting in a studio.

I was also just using FCP 5. Just turn off deck control and then "capture now" using a Decklink 720P60 preset.
You could also capture live HDV in 720P30 mode with FCP5. I've done that before, but anything going down the firewire is in no way 'uncompressed.' Same goes for DV Rack. You can transcode into an uncompressed codec, but the image has already gone through one stage of MPEG2 4:2:0 compression.

Would you need the Decklink HD PRO 4:4:4 or would the less expensive Decklink HD PRO 4:2:2 be ideal? Is the analog component out of the cam 4:4:4 or is it 4:2:2?

Good question. Is the analog output of the HD100 created from a 4:2:2 or 4:4:4 source? I don't know for sure, but common sense says to me that it is actually only 4:2:0 - since the colour space is probably a property of the CCDs (at the time they are scanned) and image processor and not the MPEG2 encoder. Maybe someone "in the know" can confirm this for us.

Either way, the 4:4:4 is definitely overkill for most HD formats. Typically I am digitizing HDCAM originated material or 35mm to HDCAM film transfers, and standard HDCAM is only 3:1:1.
I've never actually used the 12-bit 4:4:4 because it requires dual-stream SDI, and I've never worked with any sort of deck in that format. Also, it eats up hard drive space like crazy. I suppose 4:4:4 12-bit would be used with something like a Thompson Viper.

So I guess the short answer is that 4:2:2 would be fine. Blackmagic makes three flavours of Decklink HD in 4:2:2 starting at $595.
You might even be able to find a much cheaper analog component to SDI converter.

Helpful!
 

Thanks Tim, thats really helpful.

Would does SDI mean? And I am doing green screen work with the HD101 so any idea whether it would be worth getting the 4:4:4 version of deck link or would it be overkill?

Trevor

SDI - Serial Digital Interface.
In a few words it is the digital version of the Composite signal (format is different YCrCb though) which can be transmitted on the same common Coax cables used for Video.
Since it is digital, you have no quality loss of the signal on long cables and 50/60 Hz video hum is gone between devices which are connected on different power sockets.
The video format is the SD signal 720x480 NTSC / 720x576 PAL 270Kbits/sec.
The HD signals are possible with the HD-SDI signals upto 1,48 Gbits per second.
Capture cards which have SDI/HD-SDI input don't use analog components to capture the video which gives better quality through less conversions to digitize the video signals.

The YPrPb signal coming out of the HD100 (sometimes wrongly refered as YUV) is the analog version of the YCrCb.
So if you have a capture card who has digital inputs (HD-SDI or SDI) you need concersion boxes. It's best to keep the analog signals as short as possible and do the conversion close to the camera and use the SDI/HD-SDI with longer cables to connect to your other equipment

You could also try the Kona card - they make a version which includes analogue inputs - a Mac guy could tell you if these things are any good but they would do away with the need for an HD-SDI converter:

http://www.aja.com/products_kona.html#lh

and because it includes DVCProHD hardware support it would require much less processing power, and disk space.

They also make a mini SDI converter if you want to go with the Decklink card:

http://www.aja.com/hd10a.htm

and finally they make a Windows version that at this stage only supports uncompressed codecs:

http://www.aja.com/products_xena.html

The other place to look is Miranda but I have always found them to be more expensive.

Thanks
 

Thank you gentlemen, vey helpful.

Trevor

With XenaHD you can capture also to CFHD.
http://www.cineform.com/products/ProspectHD.htm

Greenscreening with the JVC
 

So let me get this straight - the signal coming out of the component jacks is uncompressed 8-bit NTSC (or PAL, of you've got the 101) with 4:2:0 color sampling, right?

More importantly, has anyone tried Tim's hypothetical green-screen studio setup? I'm wondering if the 4:2:0 (specifically, the '0') would cause grief when attempting to pull the keys shot on said stage.

I'm hearing that post houses are doing fine chroma key work with properly lit greenscreens shot at 4:2:2 (e.g. 4:4:4 may only be necessary for the most demanding situations) but I'm wondering if the otherwise immaculate signal provided by Tim's workflow (only one A/D conversion) would be fatally undermined by too little chroma sampling at the outset.

No, that is not straight (the 420). That is a theory and not confirmed. I have chromakeyed with HD-100 content using Primatte, Boris and Liquid YUV (uncompressed) with very nice results. Do you have some camera footage to try chromakey? What keying software do you use?

No, the component signal is a full 1280x720 4:2:2 sampled at 10-bit, plenty of chroma resolution to pull a great key. See indiefilmlive.blogspot.com for discussion regarding an effect heavy feature that is using the HD100.

Note: 100 and 101 have both 50 and 60p modes, there is no PAL or NTSC here.

Very interesting Serge - when I emailed them, Gerry said they weren't supporting compressed codecs yet on the Xena, but they definitely had plans to. That was only 2 days ago.

So is that hardware support on the XenaHD or are you relying onthe processor converting the uncompressed AVI to ProspectHD "on the fly"?

Prospect HD does all the compression in software, in real-time, no hardware acceleration is required on the Xena card.

Thanks David - what kind of processing power / memory do you need to achieve this (with a safety margin)?

Does ProspectHD take any advantage of your graphics card ie is the graphics card important?

Graphics card is not very important, any recent card will work fine. The system specs for Prospect HD are listing here : http://www.cineform.com/products/ProspectHDConfig.htm , but generally a dual proc Opteron system with 2GB is fine. It all depends I what you want to do.

What kind of spec's needed if you were to capture with AspectHD? Same?

That is truly excellent information. It seems like such an obvious marketing point, I can't figure out why JVC doesn't mention it on their site.

And this is a great link. I've just bought an HD-100, so I've VERY interested in seeing just how far it can be pushed. It looks like these guys are already doing it. Cheers.

No, Aspect HD can get away with much cheaper PCs (although fast ones are still nice.) We say the minmum PC is around 2.8 P4, yet we have customers using 1.7GHz P-M laptops and still getting real-time with Aspect HD.

David, you talking about real-time transcodingfrom mpeg2/ts to Aspect HD through firewire on 1.7GHz P-M laptop or capture through component(JVC) or HDSDI (Canon)? What is device with component/hdsdi for laptop exist?

Phew - that's not going to work for me - I want to build something lightweight and portable. Hardware support on a card like XenaHD would make it viable.

John,

As the XenaHD card or Xena HS requires PCI-X you will not be able to build anything truely portable, as these cards require a work-station class motherboard. The soon to be available Xena LHe will work on PCI-e bus, so that will allow desktop class PCs to be used (and maybe shuttle class), when that card is out we may change our system requirements, although you will still need the fastest Dual Core CPU for real-time compression 10bit compression at 60p (note: if you only intend 10-bit at 720p24 then most P4 class CPU can do it.)

No, I was talking real-time playback on a laptop. For that low-end laptop you would still have transcoding delays, although for 720p24 it will be surprizingly fast.

Fortunately a component/HD-SDI input to a laptop doens't exist yet. When it does, CineForm is will be able to do some amazing RT captures. So please keep an eye out for the hardware that can do this.

Hi David. Yes I was asking about using AspectHD in the same vein as ProspectHD was being discussed. Component/SDI capture. So what are the specs needed for say Xena LHe capture to AspectHD. I would be quite happy capturing 8bit 4:2:2 (AspectHD) vs. the 10bit 4:2:2 (ProspectHD) for the time being. Being I own ApectHD and don't plan on a dual Opteron anytime soon, what do I need?
What would it take 480p60 from my HD10 vs. 720p60 HD100 (future cam)?

Aspect HD doesn't currently support live capture from anything but FireWire. Capture from a Xena card is Prospect HD feature.

Wanna fix it ? ;>)

There's already shuttle boards that support 2 PCI-e slots and the LHe is already advertised on AJA website - I didn't realise it hadn't been released yet.

My point was that seeking hardware support from a card like the Xena would negate the need for a really fast dual proc machine. Technically or commercially that may not be possible (I'm guessing they may support DVCProHD as they do this already for their Mac based Kona cards) but I thought it was a reasonable idea.

David, but old version of Aspect HD 1.0 or 1.2 have no restriction for live capture through DS and VFW ?

There seems to be some confusion, Aspect HD does support capture using the Xena card, only Prospect HD does. This is no way affects the DS or VFW codecs.

I just read the thread and gained more confusion! Tim (or anybody), could you answer me this? A Blackmagic sales/support person told me the multibridge takes away the need for their capture card. Is what you did possible with just this and you used the card because it already existed in your rig?

I would be pulling my hair out if I had any!

Rich,

Who is your question for? Maybe you can re-ask. What are you hoping to achieve, and what system to you hoping to use?

They're wrong. The standard "Multibridge HD" interfaces with the SDI in and out on the Decklink HD. The multibridge converts analog sources to digital SDI and vise-versa.

The sales person may have been referring to the fact that Blackmagic is now bundling the Decklink Plus card with the original SD multibridge, and a PCI Express card with the Multibridge Extreme (for SD & HD.)

However, you still need at least a Decklink HD to interface with the standard Multibridge HD.
Or maybe I should say you need a Multibridge HD to use analog signals with a Decklink HD.

Tim, Can you recommend a set-up for LIVE capturing on location? I was thinking of using my laptop as a controller, GRaid as the harddisk for the capturing and perhpas some video card with firewire to transfer the live signal. I am also trying to get a set up for capturing LIVE audio into Pro Tools instead of using a mixer and recording device on set, but rather my laptop and a G-Raid to record onto, since I will be able to EQ and Mix it live uncompressed.

Any ideas?

Thanks Duke

Brian - the firewire signal is exactly the same as the one being recorded to tape. If your object was to capture the uncompressed signal that won't work. If you merely want to capture what's going to tape live then you won't need a GRaid - any decent external firewire drive should be capable fo capturing the signal. If your laptop is a Mac it should have firewire built in so you won't need anything else except for some software to capture with.

If you want to capture the component HD signal and you are Mac based, you could capture directly to DVCProHD using AJA's KonaLH card (the one with the analogue component HD interface), but you would need a G4 or G5 on location as these cards require a PCI slot.

I don't know if anyone here has tested that setup so it would pay to do that first.

and uncompressed?
 

But can the AJA's KonaLH capture directly to uncompressed 8bit or 10bit HD too, or does it only capture in DVCProHD format?

Thank you.

This would be a question better directed to tech support at AJA for the definitive answer.

For my take based on the website information it will digitise to any Quicktime format (both in 8bit and 10bit and it will downconvert on the fly to SD) BUT DVCProHD is the only one that is supported by hardware compression on the card (or the only one they advertise). So to digitise to another codec you need:
1. one that supports JVC's HD60P format,
2. and then if it's a compressed codec you need a LOT of processing power,
3. if it's uncompressed you'd need a fibre channel RAID system and a LOT of storage, all of which can be problematic.

It appears it does support HDV playback in hardware.

I understand
 

Thank you.