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Huge Drop in Bit Rate after capturing - DVCPRO HD

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Tj Alston
Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 9, 2010 at 10:18:39 pm

Hello again,

While working on a show we were digitizing our footage at the end of every day. We were shooting on an HDX 900, and we were using DVCPRO25 tapes. We were told that this wouldn't be a problem, and that our images would still be HD.

The footage was captured by hooking the camera directly into the computer via firewire and capturing the footage through FCP. The capture presets DVCPROHD 1080/60i or 108024pA. It's been so long I honestly can't remember which, but it would have only been one of these two.

The entire series has been edited, locked, and sent off to the post house. Now we are hearing from the post house that we captured the footage at 14 mb/s, instead of 100 mb/s. I am completely at a loss as to why this would have happened.

Can anyone offer a suggestion as to what might account for this discrepancy?


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Michael Gissing
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 9, 2010 at 11:15:18 pm

When you look at the footage in the bin, scroll across the columns and see what code you captured with and the co-responding frame size and data rate. Perhaps the post house was confusing Mbits/sec with mbits/sec.

I don't know that camera but can it downconvert to DV codec when you capture. I know HDV cameras do. Even so, if you did capture as DV then it will show that as the codec and the frame size will be SD.

If you still have the tapes and they were shot in HD, then you can recapture if you had correctly logged the reels and captured with timecode control.


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Rafael Amador
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 12:58:37 am

[Tj Alston] "the footage at 14 mb/s, instead of 100 mb/s. "
I don't know any DVCPro flavor that works at 14 Mbps. the lowest data-rate that I know is the 25 Mbps of DVCPro25.
rafael

http://www.nagavideo.com


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Shane Ross
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 1:33:52 am

Dvcpro HD 1080p24, when captured as 23.99, has an actual data rate of 14Mbps. Look at the compressor. Should be 1080i60.

Shane



GETTING ORGANIZED WITH FINAL CUT PRO DVD...don't miss it.
Read my blog, Little Frog in High Def


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Jeremy Garchow
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 2:19:46 am

Mind your bs.

That's 14 MegaBYTES persecond, not bits.

1080 23.98 DVCPro HD with audio equals roughly 14 MB/sec.


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Tj Alston
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 2:33:48 am

Ok, so the footage that I captured has a data rate of 14 Megabites/s, and DVCPRO HD records at 100 Megabits/s. What then is the issue that the post house would be having with the captured footage? They said that the footage was captured at an inferior quality, but if I'm understanding the numbers correctly than it shouldn't be inferior.


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Jeremy Garchow
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 2:57:21 am

I'm confused about that as well.

We need more info about what your project says about the clips in the browser.

Do you have tape backups just in case?


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Tj Alston
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 3:04:45 am

I'll be able to answer that in the morning.

We do have everything on tape. The post house is just wondering why they have to reconform all of the footage in order to do the onlines, and I want to be able to give them an answer.


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Shane Ross
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 5:04:14 am

[Tj Alston] " The post house is just wondering why they have to reconform all of the footage in order to do the onlines"

They don't. Not if you captured DVCPRO HD via firewire as DVCPRO HD. You are already at full quality.

Shane



GETTING ORGANIZED WITH FINAL CUT PRO DVD...don't miss it.
Read my blog, Little Frog in High Def


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Michael Gissing
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 2:58:41 am

Quite right Jeremy. Mind the bB's and the mM's


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Shane Ross
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 3:05:53 am

DVCPRO HD is 100mbits. MegaBITS per second. FCP doesn't display megabits...it shows megaBYTES. There is math involved... 1 megabits = 0.125 megabytes. So DVCPRO HD is a 12.5MB/s. But it was initially a 720p format...720p60 is 12.5MB/s. 1080i is more...depending on the frame rate.

The post house is wrong. If you capture as DVCPRO HD 1080pA 23.98...and you edited in that format, and you exported a self contained movie...you are at full resolution. They are confused.

Want a different post house? I'm available. In L.A.?

Shane



GETTING ORGANIZED WITH FINAL CUT PRO DVD...don't miss it.
Read my blog, Little Frog in High Def


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Rafael Amador
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 4:11:46 am

Yes, I think the people in the Production house are wrong.
I bet the file is 14 MB/s no 14 Mbps.
rafael

http://www.nagavideo.com


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Wayne Carey
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 7:17:46 pm

Yet, another reason Apple and FCP should have options to show use our bit rates in the desired method that we prefer. Sure would be a nice option.

Also... There should be a requirement for ALL video production personnel to learn the differences in posted bit rates. When you look at camera specs, depending on the manufacturer, they show it in one of the two forms, further confusing people.

_______________________________

Wayne Carey
Schazam Productions
http://web.mac.com/schazamproductions
schazamproductions@mac.com


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Gerald Bouget
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 5:51:55 am

The post house must have read the rate in MBYTES/S and not in Mbits/s, since 14mbyte/s is about the same than 100 mbits/s.


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Chris Tompkins
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Sep 10, 2010 at 12:30:21 pm

Tell you shot and captured DVCPRO HD.
It is @ full quality.

Chris Tompkins
Video Atlanta


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Dixon Johnston
Re: Huge Drop in Bit Rate after capturing - DVCPRO HD
on Feb 22, 2011 at 5:31:24 pm

You can also open a clip in Quicktime Pro and show movie inspector (cmd+i) to see how it translates to "mbits/s" as opposed to reading FCPs "MB/sec"

Dixon Johnston
Creative Services Director-WRIC


Aquisition: P2 500, Beta SX & SP
Edit: FCP-AJA IO-SD-HD 720P


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