View Full Version : Is the HVX component output before or after compression?


Gunleik Groven
August 19th, 2007, 05:19 AM
Simple question, hard do find a definite answer...

Gunleik

Cengiz Ozgok
August 19th, 2007, 10:33 AM
I don't know what you exactly mean but DVPRO is also a compress format.

Kaku Ito
August 19th, 2007, 06:15 PM
I'm pretty sure it is uncompressed.

Leonard Levy
August 19th, 2007, 08:50 PM
I believe the answer is it is already compressed as DVCProHD.
You cannot get an uncompressed signal from the HVX200.

Cengiz Ozgok
August 20th, 2007, 06:19 AM
Don't get confuse that thinking the DVCPro is not compress format.
And the HDV format compress only.

The only diffrence is that the DVCPro is more professional compress that means it is non frame dippendent compress.
And the HDV format is a frame dippendent compress.
There is nothing excist on this camera that make a directly uncompress output without recording first as like the camera's as Canon XH1 and XH G1 well can produce directly without first recording so uncompress output for example.

Barry Green
August 20th, 2007, 09:55 AM
I believe the answer is it is already compressed as DVCProHD.
You cannot get an uncompressed signal from the HVX200.
Of course you can. The live output is completely uncompressed.

Leonard Levy
August 20th, 2007, 11:26 AM
OK Barry, now I'm confused - Isn't DVCPro100 already a compressed format?
Do you get something different from the live output than you get recorded to the P2 card?

- Lenny

Barry Green
August 20th, 2007, 12:19 PM
DVCPRO-HD is of course a compressed format. But the live outputs bypass compression. If you point the camera at a scene and record the signal coming off the analog component output jacks, you'll be recording 100% pure uncompressed HD video.

If you are trying to record the firewire stream, that's compressed. But the analog outputs are uncompressed.

Leonard Levy
August 20th, 2007, 12:35 PM
Yow, How did i miss that in the last year and a half. I guess that's what happens when you don't read your book cover to cover.

So - are there options for recording higher quality from the analog outputs that I am unaware of? Is there anything to gain here? No one ever talks about it.

- Lenny

Cengiz Ozgok
August 20th, 2007, 02:54 PM
I dont have this camera yet I will get it friday and thought that has no analog output.
Wow thanks Barry Yoh !

Barry Green
August 20th, 2007, 03:25 PM
So - are there options for recording higher quality from the analog outputs that I am unaware of? Is there anything to gain here? No one ever talks about it.

It could be done, but it's pretty much not done because uncompressed HD is so extraordinarily taxing on system resources. You could use an analog HD capture card, or you could use a component->HDSDI converter box and capture the converted output of the HDSDI in an HDSDI capture board.

But -- basically, it's a lot less interesting to HVX owners than it is to HDV owners. I mean, the only portable-ish HDSDI recorders are things like the DVCPRO-HD tape decks, and what's the point of piping analog uncompressed video over to a DVCPRO-HD tape deck, when you could just record DVCPRO-HD directly?

So it's entirely possible, but recording uncompressed HD is not a trivial task and I don't know of too many people who bother.

Leonard Levy
August 20th, 2007, 03:36 PM
Thanks,
I guess its not such a revelation then.

Jason Boyce
August 21st, 2007, 10:58 AM
I worked on a gig recently where the director brought a Sony HDV cam, HD-SDI and two one terabyte RAIDs and used a mac pro to capture and compress on the fly to DVCPRO 1080i. It worked great except for the part where the RAIDs kept crashing and then finally completely crashed and took the project down with it. Luckily there was tape in the camera, too.

Dan Brockett
August 21st, 2007, 01:43 PM
I worked on a gig recently where the director brought a Sony HDV cam, HD-SDI and two one terabyte RAIDs and used a mac pro to capture and compress on the fly to DVCPRO 1080i. It worked great except for the part where the RAIDs kept crashing and then finally completely crashed and took the project down with it. Luckily there was tape in the camera, too.

Thanks for the story Jason. As Barry alludes to, shooting live into an uncompressed RAID system is insane in most instances, too many variables to cause crashes. Not worth it in most cases unless your shots are easily repeatable.

Dan

Jon Fairhurst
August 21st, 2007, 02:18 PM
We shouldn't confuse the workflow of shooting with a RAID with stories about crashing RAIDs. It's clear that the RAID in this story was not healthy. It could have been due to a crummy controller, the use of consumer drives, high temps in the case. Who knows.

That said, a tape backup is a good idea in any case.

The problems I see (given reliable hardware) are 1) the camera is tethered, 2) you need mains power, and 3) if the setup has fans, the audio might be degraded.

But I'd like to second the opinion above: capturing the uncompressed output makes more sense with an HDV cam than with DVCPRO HD. It also makes more sense with an HDMI output than a CAV output. (Note that Blackmagic has a cheap HDMI capture card available: http://www.blackmagic-design.com/products/intensity/ It's $350 with analog+HDMI and $250 with HDMI only.)

Jason Boyce
August 21st, 2007, 09:21 PM
Both the Mac Pro & the RAID server were both brand new, had been tested and were working perfectly when we started, but shooting conditions just got to them. By the end of the shoot, neither would come up and were sent off for repair. We were shooting in a dusty warehouse with a bunch of lights so it probably overheated, but this is very much real-world. This kind of stuff might work in a studio, but I wouldn't take a chance on it in the field. The clients were looking REALLY upset when they found out the high-quality uncompressed footage was gone.

Leonard Levy
August 21st, 2007, 09:24 PM
How does this process work - capturing to an HDV camera from the analog component output?
Could you do this as back-up while capturing to P2?

Chris Hurd
August 21st, 2007, 10:00 PM
How does this process work - capturing to an HDV camera from the analog component output?Not sure what you mean... you can't capture *to* an HDV camera. You can only capture *from* it. You can use an HDV camera as a deck and record with it, but only through FireWire or the standard definition analog input. HD component video is output only. I think you probably meant to ask how can you capture *from* an HDV camera from the analog component output, and you can do that with a component video capture card on your computer, just remember that the camera's analog component output is video only.

Could you do this as back-up while capturing to P2?Again, you don't capture to P2, in fact you really don't capture from it either, not in the strict sense of the term because P2 uses an edit-ready file format called MXF and what you do to get it into your editing system is called ingest, not capture. If you want to back up your P2 data, you simply copy the files once they're ingested.

Gunleik Groven
August 23rd, 2007, 06:55 PM
To make this clear:
We capture from 5 hvx's through the component output to uncompressed hd.
The workflow is taxing, but it still works -;)

Thing is (for me) it seems like it is well worth the extrea bandwith and hassels, but that might be exclusively me.

Gunleik

Leonard Levy
August 23rd, 2007, 11:50 PM
Sorry, i guess my question was a little stupid, and the term capturing to P2 may have been technically incorrect - I jsut meant recording to P2. I just didn't understand what a previous post was saying about using Sony HDV cameras and was trying to clarify. I got the impression they were using it with an HVX and the analogue oputputs but that was mistaken.

I still don't get what Gunleik is doing. How are you recording and why? What are the pros & cons?