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Old April 14th, 2007, 04:56 PM   #1
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Capturing using firewire or capturing using capture card? The difference?

Hi all

I've been looking at Blackmagic's capture cards and it got me thinking how could a capture card be of difference when ingesting HDV/DV materials as compared to capturing them using firewire?
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Old April 14th, 2007, 07:59 PM   #2
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One advantage of capturing HDV with a capture card is that in real time you can capture to a codec that's more suitable for editing, for example, DVCPRO HD or some uncompressed format. The "conform" time with HDV on a Mac, even on a Mac Pro Quad is a pain.

Another advantage of a capture ard is they also offer HD component or HD SDI output for monitoring on an HD monitor, essential for color correcting on a broadcast monitor.
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Old April 16th, 2007, 09:48 AM   #3
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Originally Posted by David Tames View Post
One advantage of capturing HDV with a capture card is that in real time you can capture to a codec that's more suitable for editing, for example, DVCPRO HD or some uncompressed format.
By that you mean that I dont have to deal with the long GOP which comes with HDV materials right?

Would capturing to a better codec also means that I'll have better colour space to work with for colour correction/grading as compared to native firewire capture?
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Old January 21st, 2008, 07:14 PM   #4
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Conclusion:yes or no for capturing with dedicated capture card..?

Hello!
I would also like to have an answer to this unfinished question...I did a search in the forum but all I found was the need of having a capture card for previewing video on a monitor.

To sum up:
If someone captures to a miniDV tape a HD clip (let's suppose Sony Fx1 in HDV mode), will it make any difference, on the file you capture to hard-drive, wether if capture was done via a "SuperGT" capture card instead of a "regular-bundle" firewire port?

What quality increase do I get? Will it provide me better images?

Regards,
Nelson
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Old January 21st, 2008, 09:09 PM   #5
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This confuses people a LOT - and it shouldn't.

You get NO benefits from a dedicated card if you're working with HDV.

Here's why...

You must think of your entire edit workflow as a pipeline.

If you're working in DV or HDV, your imaging is being done at STANDARD DV data rates. So the amount of "water" at the start of the pipeline is relatively small. 25Mbps small. This is true of DV, DVCAM and HDV - ANY 25Mbps format.

If that's all the data rate you're ORIGNIATING there will be NO advantage to doing anything other than simple firewire capture - and you will NEVER need a more robust capture card. Period.

Regular old Firewire 400 has PLENTY of bandwidth to handle that stream. Period.

The place where Kona cards and AJA cards and the rest come into play is if you are ORIGINATING your material at higher data rates - like with DVCPRO-50 or digitizing from Analog High-def - or a Genesis, or a RED camera, etc. - THEN and ONLY then will a workflow that supports higher data rates THROUGHOUT the system make sense.

And you MUST maintain those higher datarates up and down the workflow. You can't dump to DVCAM for editing then dub that back to a higher def format - because once the signal is downsampled, it's DOWNSAMPLED. (you can work with offline proxies, but the END to END datastream from source tape to master MUST preserve the high-def signal or you're wasting your time pretending to work in high-def)

So your need for a dedicated card STARTS and ENDS with your ability to originate, work with, monitor and output HIGH DEF. Period.

If you don't have high-def monitors, a deck, and the ability to output a high-def master - the card will just sit there and depreciate. (quickly!)

There's a sorta-maybe exception to this is if you're preparing SD or HDV footage for HD broadcast. Then it might make sense to prepare your titles and graphics in high def over SD footage - and a card will help you do that on a somewhat older computer - but that's a pretty specialized game.

Again, if you aren't finishing to HD, there's NO need for any cards.

And with the continued processing speed increases in computers - the ability of native Quad and 8 core processors in stock computers to handle even High DEF (like Apple's new codec solutions) is getting better all the time and making it increasingly unnecessary to require specialized hardware to work with native HD streams in a standard computer box.

So if you need real HIGH DEF and need it RIGHT NOW and you don't have a brand new computer - look into those outboard cards. They're the way to go.

If not, forget about them.

FWIW.
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Old January 22nd, 2008, 01:49 AM   #6
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Now there is a nice cold splash of common sense Bill.
I haven't seen it put so clearly before.
(and I feel better for getting ready to hurl my
money at one of the new Mac Pro's)...

David
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Old January 22nd, 2008, 02:30 AM   #7
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Our DV Feature

I agree with most everything Bill said but would like to add my situation.

For our feature, we shot on 24P DV (XL2), with a 2:3:2:3 pulldown. I captured all 35 hour long tapes via firewire. I later removed the pulldown (creating true 23.976 media) but was shocked to see the loss in quality. There were artifacts, movement blur and other nasty traces.

Additionally, our perspective distributor warned us about editing in DV. He requires an HDCAM SR @ 23.98 1080.

I made the decision, as it is always better to catch a workflow problem earlier than paying through the nose later.

I deleted all 35 tapes. Our editor threw away all final cut project files. And all the logged timecode logged by the director were moot.

Trying the process again, I captured 35 tapes via a Sony DSR-1800 with SDI/AES (AJA Io) into final cut pro using the "SD Pro-Res HQ" setting.

Once all 35 tapes were captured I went to After Effects CS3.
In after effects, we removed the pulldown, created and stretched our SD to 1080 Pro-Res 23.976 media.

The result - WAY BETTER. More latitude with the colors (upconverted on the DSR-1800), less distortion in the blacks and zero signs of interlacing. I'm not prescribing this for anyone yet I honestly see a huge difference in the DV media once upressed.

Some say Garbage in - Garbage Out.
DV upressed over SDI to Pro-Res, Upconverted to HD - is totally better than Firewire anything (in my opinion of course).

Hope this helps.
-C
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Old January 22nd, 2008, 06:18 AM   #8
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Quote:
Originally Posted by Christopher Drews View Post
I agree with most everything Bill said but would like to add my situation.

For our feature, we shot on 24P DV (XL2), with a 2:3:2:3 pulldown. I captured all 35 hour long tapes via firewire. I later removed the pulldown (creating true 23.976 media) but was shocked to see the loss in quality. There were artifacts, movement blur and other nasty traces.
There's your problem, you needed to shoot in 24p 2:3:3:2 format for clean i frame removal. The cadence in 24p 2:3 is AA BB BC CD DD therefore frame C has to be reconstructed from adjacent fields in different frames. This has to be processed and rendered (and may cause ALL your media to be processed and rendered, even complete discrete frames) adding artefacts.

24pA works in AA BB BC CC DD, therefore, the third frame is simple dropped or skipped with no loss as the information is fully present in the proceeding and following frames.

Howe were you converting from 60i to 24p?
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Old January 22nd, 2008, 06:42 AM   #9
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I'm convinced with Bill Davis arguments.
Thanks a lot for clearing it out.

Regards,
Nelson
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Old January 22nd, 2008, 07:41 AM   #10
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Quote:
Originally Posted by Christopher Drews View Post
Some say Garbage in - Garbage Out.
DV upressed over SDI to Pro-Res, Upconverted to HD - is totally better than Firewire anything (in my opinion of course).

Hope this helps.
-C
That doesn't follow. All it means is that somewhere in your FireWire-based workflow there is a flaw (as Dylan suggests).

The source material is DV. If you send it via FireWire it is still DV. FireWire introduces absolutely no side effects - adverse or beneficial. Software can convert the DV material to HD material as good as any hardware solution. After all, the hardware solutions are merely dedicated computers running dedicated code. It's a matter of having the right software tools for your FireWire workflow.

The advantage of the SDI route is one of speed - that's all.
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Old January 22nd, 2008, 09:41 AM   #11
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John,

having said that, there are advantages to doing effects, titles and colour correction in another codec. The DV codec is very limited in terms of colour space compared to other heavy duty codecs (it was never intended as a professional format).

But you're right: artefacts, motion blur and interlacing problems are NOTHING to do with firewire, but to do with a error in the workflow in the first place.
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Old January 22nd, 2008, 11:07 AM   #12
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Quote:
Originally Posted by Christopher Drews View Post
DV upressed over SDI to Pro-Res, Upconverted to HD - is totally better than Firewire anything (in my opinion of course).

Hope this helps.
-C
Capturing DV uncompressed via SDI will help reduce some of the chroma noise so in a situation like this where every bit and byte counts since you are taking DV to HD I'd say the additional cost and storage space of capturing DV over SDI is worth it.

Graeme Natress wrote a very good article on chroma sampling in FCP a couple of years ago.
http://www.lafcpug.org/Tutorials/bas...ma_sample.html


-A
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Old January 22nd, 2008, 12:04 PM   #13
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Originally Posted by Dylan Pank View Post
John,

having said that, there are advantages to doing effects, titles and colour correction in another codec. The DV codec is very limited in terms of colour space compared to other heavy duty codecs (it was never intended as a professional format).

But you're right: artefacts, motion blur and interlacing problems are NOTHING to do with firewire, but to do with a error in the workflow in the first place.
Absolutely but the OP's source originally derives from DV so the colour space issues can be addressed equally well via a post-FireWire process as via the SDI route.

Either route involves "nothing more than" digital signal processing and, if anything, the FireWire route offers much more flexibility than a fixed hardware solution - it just takes a l-o-t longer.
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Old January 22nd, 2008, 04:02 PM   #14
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Originally Posted by Andrew Kimery View Post
Capturing DV uncompressed via SDI will help reduce some of the chroma noise so in a situation like this where every bit and byte counts since you are taking DV to HD I'd say the additional cost and storage space of capturing DV over SDI is worth it.

Graeme Natress wrote a very good article on chroma sampling in FCP a couple of years ago.
http://www.lafcpug.org/Tutorials/bas...ma_sample.html


-A
Thank you Andrew. You stated what I see. That is exactly why the SDI solution is better for my needs. The chroma noise is visibly less than what it was over firewire. As for 2:3:2:3 pulldown, it indeed was a poor choice, one I intend to correct in future projects.
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Old January 22nd, 2008, 11:20 PM   #15
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well it seems that sony DV decks with SDI out do some chroma smoothing ( Blurring ! ) where the SDI may look a little bit better when captured via SD to uncompressed or a lossless codec. with HDV, I would NOT use DVCpro HD anymore because it trashes 25% of the horizonal resolution. you can see the difference, even in a SD down convert. instead use a lossless full raster codec like ProRes when using a capture card.
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