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Panasonic DVCPRO HD Workflow


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#1 Andy O'Neil

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Posted 21 July 2005 - 11:57 PM

A certified Apple FCP technician said with 80% conviction (judging by the cadence of his voice) that DVCPRO HD footage captured by Panasonic's Varicam could be captured to FCP 5 at a compressed rate. I'll go ahead and refer to this as offline editing.

It was stated that the data rate of the recorded material could be reduced from 100 Mbps (not to be confused with MBps) to 5.7 to 14 Mbps. He concluded that a 7x400 GB RAID system would be more than enough storage for 200 hours of compressed HD footage.

Is this true? He was not clear if these numbers referred to 720p or 1080i, but I'm more concerned with 720p.

If these numbers are correct, what determines the range (5.7 to 14 Mbps)? Why would this de-ressed material have variable data rates as opposed to a fixed number? What affects this variability?

Thank you.
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#2 David Mullen ASC

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Posted 22 July 2005 - 12:31 AM

He could be referring to the fact that if you shoot at 24P, which is recorded to 720/60P on the Varicam at 100 Mb/sec, then when importing, if the system can remove the excess frames and only transfer the true 24P frames, then the data rate is only 40 Mb/sec instead of 100.
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#3 Andy O'Neil

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Posted 22 July 2005 - 04:38 PM

Thank you, David.

So do I have this right?

DVCPRO HD records at 100 megabits per second
A megabit (mb) is 1/8 of a megabyte (MB)
Therefore, DVCPRO HD records at 12.5 megabytes per second (I got that number by dividing 100 by 8)

So, to determine how much disk space one would need to capture 100 hours of DVCPRO HD, I did the following calculation:

12.5 MB X 60 = 750 MB per minute
750 MB X 60 = 45,000 MB per hour (45 GB per hour)
45 GB X 100 hours = 4500 GB per 100 hours (4.5 TB per 100 hours)

Is this correct? And if it is, would a 5.6 TB RAID system be enough storage to edit with?
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#4 David Mullen ASC

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Posted 22 July 2005 - 07:07 PM

Someone with more editing experience than me should answer this one -- that probably means most of the people on this forum...
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#5 Michael Most

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Posted 22 July 2005 - 07:16 PM

12.5 MB X 60 = 750 MB per minute
750 MB X 60 = 45,000 MB per hour (45 GB per hour)
45 GB X 100 hours = 4500 GB per 100 hours (4.5 TB per 100 hours)

Is this correct? And if it is, would a 5.6 TB RAID system be enough storage to edit with?


Your numbers are basically correct. However, why do you feel it's necessary to have everything you shot on line, in HD, for basic editorial? Why not bring it all in as, say, DV, and use 1/4 of the storage for the same amount of material? Following your offline, you can then bring in the original HD material for a final conform. Much better use of storage space, not to mention much more efficient operation of your editing software and computer.

I really don't understand why people here doing projects with voluminous amounts of source material seem to feel that it all needs to be at full resolution all the time. There is no advantage to this approach, and a hell of a lot of disadvantages, not to mention additional cost.
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#6 Phil Rhodes

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Posted 22 July 2005 - 07:33 PM

Hi,

I think the main reason is that storage is cheap, and the online/offline cycle is fraught with difficulty and opportunity for rather horrible errors. There's also nothing quite like cutting an offline and only discovering that your only-good-take, sequence-breaking shot is actually soft at full res.

When you're talking about 2K stills sequences, fine, but if DVCPRO-HD is only twelve and a half megs a second, why mess about?

Phil
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#7 Andy O'Neil

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Posted 22 July 2005 - 07:40 PM

I'm not adverse to offline editing; I'd actually prefer it. However, I don't want to have to downconvert anything. That takes time and costs money too.

I'd rather capture the HD footage directly to FCP at a lower resolution, but the Apple tech support reps I've spoken to cannot seem to give me a concrete answer as to how I would do this and be able to batch capture uncompressed HD footage and conform it to an EDL in the end.

Is it possible to capture DVCPRO HD footage at a lower resolution without having to downconvert? If so, I'm all ears as to how one could do this.

Thanks.
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#8 Andy O'Neil

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Posted 22 July 2005 - 07:44 PM

Hi Phil,

You replied as I was in the middle of writing my reply, but you've made a very good point. If there were a way to switch between offline and online material conveniently, an offline edit would be my first approach.
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#9 Christopher Bell

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Posted 23 July 2005 - 12:50 AM

This site will answer most of your questions:

http://www.kenstone....flow_balis.html

Chris Bell
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#10 Michael Most

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Posted 23 July 2005 - 01:10 AM

Is it possible to capture DVCPRO HD footage at a lower resolution without having to downconvert? If so, I'm all ears as to how one could do this.


If you're using the Panasonic AJ-HD1200 machine (I assume you are because you appear to be taking the Firewire route), it can downconvert internally and play back the HD material as SD. There's no need to do any separate downconversion. Unless you're planning on a significant amount of overcranking, this should be sufficient. The only additional cost, and only if you're renting the deck, would be another rental for the HD loading following your offline cut. But that cost would likely be a lot less than 4.8 TB of storage compared to the 1.2 TB you would need by going the offline/online route.

I agree that it's sometimes simpler these days to stay in HD throughout if you're using the DVCProHD format. But you're talking about a much larger amount of footage than I would consider "normal" for anything less than a 50 day shooting schedule. Your choice, though.
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#11 Brian Wells

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Posted 23 July 2005 - 03:38 AM

why do you feel it's necessary to have everything you shot on line, in HD, for basic editorial?

Seeing as how 720/24p is only 40mbps vs. DV's 25mbps... For me, the question becomes "why not" ?
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#12 Phil Rhodes

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Posted 23 July 2005 - 04:11 AM

Hi,

Yes, the final decision would be how much stuff you're looking at. Even if it were a feature at a reasonably modest 10:1 or so I'd certainly capture high res. Clearly, though, you'd offline a documentary series with 50 hours of stuff.

Phil
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#13 Andy O'Neil

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Posted 26 July 2005 - 09:18 PM

If you were to capture DVCPRO 100 footage at a de-res rate, internally downconverted to SD, could you preserve time code?
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#14 Christopher Bell

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Posted 27 July 2005 - 06:53 PM

Yes your time code should remain the same. Down res does not make a lot of sense if your frame rate is 24 at 720. We just cut a show on a 12" powerbook in HD! The trick is to load your HD footage to a firewire 800 drive, then the powerbook can use the 400/800 connection to access the data. The 1200a cannot share a firewire 400 bus, so you must load your data via firewire 800. Worked without a hitch.

Chris Bell
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#15 Andy O'Neil

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Posted 28 July 2005 - 02:41 PM

Thank you, everyone.
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#16 Sivanesan

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Posted 06 July 2006 - 02:45 PM

This site will answer most of your questions:

http://www.kenstone....flow_balis.html

Chris Bell



Hi Chris and all,

Im just trying to understand the workflow of HD..... this topic is almost one year old...... but still informative......

While trying to know about the current scenario...... my dealers in india are telling me that we need to have fiber channel card and fiber storage for fcp hd online. Is it true that i need to have such a huge storage system for this. This alone cost about 10,000 US dollars for 1 TB storage (excluding G5 system and Decklink HD dual link).

They also mention that even if i need to do a pilot project or a atleast a TVC..... i need to install all these.
Is there more resources on HD workflow. I did not find any sucess with google.

Regards
Sivanesan
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#17 Dan Goulder

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Posted 06 July 2006 - 06:44 PM

While trying to know about the current scenario...... my dealers in india are telling me that we need to have fiber channel card and fiber storage for fcp hd online. Is it true that i need to have such a huge storage system for this. This alone cost about 10,000 US dollars for 1 TB storage (excluding G5 system and Decklink HD dual link).

This is what's required for uncompressed HD. If you're working with DVCPro HD, then all you need is a single hard drive, unless you need greater capacity.
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#18 Sivanesan

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Posted 07 July 2006 - 11:40 AM

Hi all,
Can't i work with a 500GB External Firewire Storage - Lacie, for HD. Initially i would like to work with few minutes footage only. Say I shoot for 10min and edit it to 2 or 3 minutes.

Regards
Sivanesan
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