Flash XDR/nanoFlash Long GOP

Fabrice Hoffmann · May 19th, 2009, 12:10 PM

Hello everybody,

I'm really interested in the Nanoflash for my JVC GY-HD251. I also use Final Cut for editing. The question is : will i need to transcode from this long gop codec to an iframe codec to edit my videos, like i do it from HDV to Apple prores ? Or is it possible to grade or do compositing and special fx in Final Cut with your codec, at 720p50 ?

I do a lot of color grading, and from this, i export still images at this end.

Thanks.

Tim Polster · May 19th, 2009, 02:26 PM

Hello Fabrice,

I use a PC running Edius and I am able to edit the XDR footage straight from the CF card in a USB reader if I choose to.

In other words, the XDR files do not tax my quadcore 9450 based system.

James Huenergardt · May 19th, 2009, 02:33 PM

Fabrice,

I know for a fact that you can record Quicktime files that do not need any re-wrapping/transcoding for you to edit them straight out of the nanoFlash into FCP.

Fabrice Hoffmann · May 20th, 2009, 01:02 AM

Thanks for the answers,

What i wanted to know is if this XDcam long gop is good enough for grading or if (like hdv is) it's a good codec for capturing things but needs to be transformed in another (iframe) codec for grading.

Bill Ravens · May 20th, 2009, 06:08 AM

Fabrice...

I think you'll find answers on both sides of the fence on this question. For my own preference, Long GOP, in any form, is not designed for editing, it is optimized for in-camera capture. Many people will argue that modern processors are fast enough to "decode" the IGPB mpeg2 encoding and allow editing. Personally, I believe you will suffer quality degredation by editing MPEG2 directly. My workflow involves transcoding the long GOP files into a Digital Intermediate(DI) before editing. Towards this end, I use Cineform, or any good 10-bit DI. However, at this point in time Cineform is not functional with the files from the FlashXDR. I believe both Cineform and Convergent Design are working the solution to this problem.

John Richard · May 20th, 2009, 07:31 AM

Another workflow for XDR/Nano Flash and FCP suggested by Tommy Schell of C-D is to set FCP to use Pro-Res as the renderer for any effects.

So effectively, the Long-GOP is left as is on the timeline unless an effect is used such as a transition of complexity - then FCP converts this complex portion of the timeline to a Pro-Res I-Frame section for swifter rendering.

There is also the options to set the boxes to capture in a couple of I-Frame formats at different data rates.

Finally, depending on the power of your Mac, the Long-GOP can be very workable. As has been pointed out, the Long-GOP used in the C-D boxes is far less computer intensive than HDV as there are less computations needing to be processed.

David Cherniack · May 26th, 2009, 04:24 AM

Quote:

Originally Posted by Bill Ravens

Fabrice...

I think you'll find answers on both sides of the fence on this question. For my own preference, Long GOP, in any form, is not designed for editing, it is optimized for in-camera capture.

I couldn't disagree more. You've probably never been editing on an Axio which leaves long GOP material in it's natve form, transcodes it on playback to 10 bit uncompressed that you can mix multiple layers of, all with RT colour grading.

Bill Ravens · May 26th, 2009, 06:39 AM

David...

If you read my post carefully, you'll notice that I didn't say Long form GOP couldn't be edited. With today's fast processors, it can be edited, and edited successfully. At the risk of repeating myself, I'll say again that long form GOP is a capture format, not an editing format. The nature of mpeg2(aka long form GOP) is to record I frames, which serve as masters. The rest of the GOP are derivatives of the master I frame. When this is edited, the processor must reconstruct the video stream, perform the edit, then deconstruct the video stream. This is no simple task, but, it can be done.

David Cherniack · May 27th, 2009, 10:49 AM

I should have let your quote run on longer to this sentence.

Quote:

Originally Posted by Bill Ravens

Fabrice...
Personally, I believe you will suffer quality degredation by editing MPEG2 directly.

You certainly can get this on systems that transcode to compressed intermediate codecs and then add effects. You don't get this on the Axio workflow for the reasons I state above.

Bill Ravens · May 27th, 2009, 11:11 AM

After reviewing matrox's website describing Axio, I see no supporting evidence that long form GOP encoding is handled any less lossy in Axio than any other DI system. Yet Axio costs $3500 with the dubious distinction of being tied to an Adobe Premiere platform. It seems Axio uses an I-frame MPEG2 DI, which is a little different than Long GOP MPEG2, altho' it IS an intraframe compression protocol. So, in effect, axio does not edit long form GOP, and it does edit a compressed DI's. I would submit that there is generational loss with I-frame MPEG2, that you do not see with full frame wavelet compression scheme DI's like Cineform.

John Quick · May 27th, 2009, 04:01 PM

Quote:

Originally Posted by Mike Schell

I know the Cineform guys are working on a solution. I'll give them a ring tomorrow and ask for an update.

Any new word on compatibility?

David Cherniack · June 5th, 2009, 08:46 PM

Quote:

Originally Posted by Bill Ravens

After reviewing matrox's website describing Axio, I see no supporting evidence that long form GOP encoding is handled any less lossy in Axio than any other DI system. Yet Axio costs $3500 with the dubious distinction of being tied to an Adobe Premiere platform. It seems Axio uses an I-frame MPEG2 DI, which is a little different than Long GOP MPEG2, altho' it IS an intraframe compression protocol. So, in effect, axio does not edit long form GOP, and it does edit a compressed DI's. I would submit that there is generational loss with I-frame MPEG2, that you do not see with full frame wavelet compression scheme DI's like Cineform.

Bill, you really should try to read things with a little more diligence. Many of your statements above are factually incorrect.

First. Axio does not use an I-frame MPEG2 DI. If timeline sections need to be rendered because of non-matrox effects they can be done in Iframe or uncompressed, 8 or 10 bit

Second, Other systems when importing long GOP will convert it to an intermediate codec or uncompressed in order to work with more than one layer, straight cuts. Axio does not. It will handle 4-8 layers of HD long GOP plus effects without any rendering depending on the processing power of the system. Then, when exporting long GOP, it converts it on the fly to HDSDI. Other systems need to render most effects, including color grading. Axio does not.

Third, Adobe Premiere is no more or less dubious than any other NLE. They all have their strong an weak points. And Cineform seems to use Premiere without complaints.

Fourth. If there is the necessity of rendering a timeline section if can be done in 10 bit uncompressed. I would submit that that's going to be better than any form of compreesion, wavelet or otherwise.

John Quick · June 16th, 2009, 02:45 PM

Any new word on compatibility?

May 19th, 2009, 12:10 PM	#16
Fabrice Hoffmann Regular Crew Join Date: Jul 2006 Location: Grenoble - France / Figueres - Spain Posts: 61	Workflow ? Hello everybody, I'm really interested in the Nanoflash for my JVC GY-HD251. I also use Final Cut for editing. The question is : will i need to transcode from this long gop codec to an iframe codec to edit my videos, like i do it from HDV to Apple prores ? Or is it possible to grade or do compositing and special fx in Final Cut with your codec, at 720p50 ? I do a lot of color grading, and from this, i export still images at this end. Thanks. __________________ _______________________ www.fabrice-hoffmann.com

May 19th, 2009, 02:33 PM	#18
James Huenergardt Major Player Join Date: Nov 2005 Location: Chehalis, WA Posts: 513	Fabrice, I know for a fact that you can record Quicktime files that do not need any re-wrapping/transcoding for you to edit them straight out of the nanoFlash into FCP. __________________ Reel Inspirations - www.reelinspirations.com Commercials, Dramas, Image Pieces, Documentaries, Motion Graphics

May 20th, 2009, 01:02 AM	#19
Fabrice Hoffmann Regular Crew Join Date: Jul 2006 Location: Grenoble - France / Figueres - Spain Posts: 61	Thanks for the answers, What i wanted to know is if this XDcam long gop is good enough for grading or if (like hdv is) it's a good codec for capturing things but needs to be transformed in another (iframe) codec for grading. __________________ _______________________ www.fabrice-hoffmann.com

May 27th, 2009, 11:11 AM	#25
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	After reviewing matrox's website describing Axio, I see no supporting evidence that long form GOP encoding is handled any less lossy in Axio than any other DI system. Yet Axio costs $3500 with the dubious distinction of being tied to an Adobe Premiere platform. It seems Axio uses an I-frame MPEG2 DI, which is a little different than Long GOP MPEG2, altho' it IS an intraframe compression protocol. So, in effect, axio does not edit long form GOP, and it does edit a compressed DI's. I would submit that there is generational loss with I-frame MPEG2, that you do not see with full frame wavelet compression scheme DI's like Cineform. Last edited by Bill Ravens; May 27th, 2009 at 01:36 PM.

June 16th, 2009, 02:45 PM	#28
John Quick New Boot Join Date: May 2009 Location: Berkeley, CA Posts: 23	Cineform? Any new word on compatibility?

May 19th, 2009, 02:26 PM	#17
Tim Polster Inner Circle Join Date: Dec 2004 Location: Arlington, TX Posts: 2,231	Hello Fabrice, I use a PC running Edius and I am able to edit the XDR footage straight from the CF card in a USB reader if I choose to. In other words, the XDR files do not tax my quadcore 9450 based system.

May 20th, 2009, 06:08 AM	#20
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	Fabrice... I think you'll find answers on both sides of the fence on this question. For my own preference, Long GOP, in any form, is not designed for editing, it is optimized for in-camera capture. Many people will argue that modern processors are fast enough to "decode" the IGPB mpeg2 encoding and allow editing. Personally, I believe you will suffer quality degredation by editing MPEG2 directly. My workflow involves transcoding the long GOP files into a Digital Intermediate(DI) before editing. Towards this end, I use Cineform, or any good 10-bit DI. However, at this point in time Cineform is not functional with the files from the FlashXDR. I believe both Cineform and Convergent Design are working the solution to this problem.

May 20th, 2009, 07:31 AM	#21
John Richard Major Player Join Date: May 2006 Location: Incline Village, Nevada Posts: 604	Another workflow for XDR/Nano Flash and FCP suggested by Tommy Schell of C-D is to set FCP to use Pro-Res as the renderer for any effects. So effectively, the Long-GOP is left as is on the timeline unless an effect is used such as a transition of complexity - then FCP converts this complex portion of the timeline to a Pro-Res I-Frame section for swifter rendering. There is also the options to set the boxes to capture in a couple of I-Frame formats at different data rates. Finally, depending on the power of your Mac, the Long-GOP can be very workable. As has been pointed out, the Long-GOP used in the C-D boxes is far less computer intensive than HDV as there are less computations needing to be processed.

May 26th, 2009, 06:39 AM	#23
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	David... If you read my post carefully, you'll notice that I didn't say Long form GOP couldn't be edited. With today's fast processors, it can be edited, and edited successfully. At the risk of repeating myself, I'll say again that long form GOP is a capture format, not an editing format. The nature of mpeg2(aka long form GOP) is to record I frames, which serve as masters. The rest of the GOP are derivatives of the master I frame. When this is edited, the processor must reconstruct the video stream, perform the edit, then deconstruct the video stream. This is no simple task, but, it can be done.