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HDV and ProRes... how to save time??

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Alessio Gemma
HDV and ProRes... how to save time??
on Feb 27, 2010 at 2:44:57 pm

Hello ti everybody,
I often shoot with a Sony HDV cam and I digitize the tape using ProRes (instead of HDC codec).
The issue is that sometimes I need to master back to tape, so FCP has to convert from ProRes to HDV again, spending a lot of time...
The question is: is it better to edit with a ProRes sequence or I can edit with HDV instead? If I need to make a SD DVD, have I to export my sequence to ProRes before to compress it in MPEG2?
thanks,
Alessio


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Shane Ross
Re: HDV and ProRes... how to save time??
on Feb 27, 2010 at 6:01:45 pm

If you are going to be laying back to HDV tape, do not capture as ProRes. You will just be converting and converting and losing resolution in the process.

[Alessio Gemma] "is it better to edit with a ProRes sequence or I can edit with HDV instead?"

If going to tape...edit HDV. If going to DVD...might be better to use ProRes.

Don't convert to something BEFORE you author...again, that is two layers of compression.


Shane



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


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Scott Sheriff
Re: HDV and ProRes... how to save time??
on Feb 27, 2010 at 6:03:07 pm

Alessio,
A lot has to do with what system you have, and how much VFX and layers in your timeline.
If you have an 8 core machine, and do a moderate amount of FX (3WCC, minor cropping) it might save time in the long run if you are going to an SD DVD.
Best way to tell is do a short test both ways and keep track of the time the entire process takes for each way.

I have a JVC 720p HDV camera, and I almost always stay HDV since I'm going SD DVD most of the time. I can pile on the FX and layers no problem using my 8 core 2.88. I have done stuff with the Sony camera too, and found that it is a lot more sluggish using it native (HDV) than the JVC. This is probably due to the JVC having a much shorter GOP (6 vs 15), and the smaller JVC 720 frame.

Scott Sheriff
Director
SST Digital Media
http://www.sstdigitalmedia.com


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Alessio Gemma
Re: HDV and ProRes... how to save time??
on Feb 28, 2010 at 11:31:14 am

Thanks Shane and Scott,
my workflow is: digitize an HDV tape, editing and burn an SD DVD plus a master to tape in HDV.
I work using a ProRes timeline: I export using self-contained to compress in MPEG2, but, of course, I have to go back to tape the system needs to reconvert the sequence to HDV before mastering.
My idea was: digitize using HDV (instead of ProRes), editing in HDV and, once finished:
1) master to tape (it's an HDV sequence, so I don't need to transcode)
2) export to ProRes from FCP to obtain a file well suited for the DVD authoring

My question is: using the upon workflow, do you think I'll loose quality or not? MAybe I need to test it?

Regards,
Alessio


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Scott Sheriff
Re: HDV and ProRes... how to save time??
on Feb 28, 2010 at 4:29:15 pm

IMHO
With that workflow I think you wold be better off staying native, and going to compressor as HDV. The benefit you get from ProRes is that it's less processor intensive and you get more real-time FX/playback. It is also a better choice if you are mixing a lot of different formats in the timeline. If your system is fast enough, and you are not adding a lot of filters, and your staying with 1080i HDV as a source, going ProRes, especially just to go to a SD DVD is unnecessary transcoding and is actually lowering the quality. But not enough that its noticeable.
Native HDV 1080 15 frame GOP, will seem a bit slower than ProRes in the timeline even on a fast system, but I think you would save time, and quality on the project overall.
Shane is the real expert, hopefully he will chip in a few more thoughts.

Scott Sheriff
Director
SST Digital Media
http://www.sstdigitalmedia.com


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Alessio Gemma
Re: HDV and ProRes... how to save time??
on Mar 1, 2010 at 11:59:05 am

Thanks for your reply!
I want to save time, but I really don't want to waste the overall quality.
Someone told me that it's not a good idea to use HDV to obtain an mpeg2, cause of the GOP structure of this codec... but it depends on the sequence complexity, as you wrote here.
I guess that it's time to test the two methods separately.... HDV and ProRes workflow.
The last question is: is it correct to export the HDV sequence as a ProRes clip before to compress it in mpeg2 or do you think it would be better to export the HDV as self-contained and compress it in moeg2 directly?
Regards,
Alessio


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Scott Sheriff
Re: HDV and ProRes... how to save time??
on Mar 1, 2010 at 5:53:31 pm

Alessio,
I think you have been mis-informed. HDV is mpeg2, and so is SD DVD.
So if your workflow is HDV to SD DVD, keep it native if your system can handle it.
So If you convert HDV to ProRes, and then Compress for SD DVD, that is two unnecessary transcodes.

Try this for an easy HDV to SD DVD workflow:
Capture footage as HDV 1080i (for the Sony camera) and edit
Render your timeline
Use 'Export Using Compressor' from the FCP file menu
In Compressor
Set the destination
Use DVD Best Quality setting
Let Compressor do its thing.
Import the two Compressor output files into DVD Studio Pro and make your DVD


Scott Sheriff
Director
SST Digital Media
http://www.sstdigitalmedia.com


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Alessio Gemma
Re: HDV and ProRes... how to save time??
on Mar 1, 2010 at 6:37:11 pm

Thanks Scott,
I'll try your workflow... I always thought that it wasn't a good idea to compress an already compressed format as HDV and I needed an intermediate codec as ProRes: but maybe I need it the only case I have to mix different formats.
Best regards,
Alessio


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Scott Sheriff
Re: HDV and ProRes... how to save time??
on Mar 1, 2010 at 8:01:21 pm

Alessio,
"I always thought that it wasn't a good idea to compress an already compressed format as HDV"

HDV is compressed when you shoot it, both the frames and the color space. Going ProRes doesn't 'uncompress' it. What it is really doing is filling in the missing info (through interpolation) from the 'P' and 'B' frames in order to create a full (I-type) for each frame of video, which reduces the workload on your system, and keeping the quality at that level. This is simplified, the whole GOP, Color Space discussion could fill quite a few pages.

No matter what HD material (HDV, ProRes, etc) you start with, if you go to SD DVD you are going to encode (compress) the footage for SD. Since SD DVD is already MPEG2, and so is your native HDV footage, unless you have a compelling reason to transcode to ProRes, staying in HDV should result in the same quality on a SD DVD, and will eliminate a time consuming step, assuming you don't need ProRes for any of its other advantages. Since HDV is already MPEG2, it might (in theory) be less compressed going to SD DVD than ProRes. I guess this would be dependent on how the code doing the compression was written.
Where you may run into quality differences is where in the process your footage is deinterlaced, since SD DVD is Progressive. You could do it in the timeline with a filter, or do it in Compressor. Just don't do it twice. This is why you might want to run some short tests and try different setting and see what looks best.

Scott Sheriff
Director
SST Digital Media
http://www.sstdigitalmedia.com


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Alessio Gemma
Re: HDV and ProRes... how to save time??
on Mar 1, 2010 at 11:36:31 pm

I agree with you, of course. My choice was driven by an article posted on Ken Stone website...
I copy and paste below something..

"A number of the new video cameras on the market shoot in HDV and XDCAM EX formats. Both of these formats use long GOP 'temporal' compression. For some people, when encoding from these codecs to MPEG2, the quality of the finished MPEG2 video may leave something to be desired. While not everyone experiences this problem, for others it can be a real issue.
There is a way around this problem. Export your HDV or XDCAM EX video from the FCP timeline to Apple's ProRes 422 codec. The ProRes 422 codec is a 10-bit, full raster, high quality frame-based codec designed to preserve quality. ProRes 422 files can be encoded to MPEG2 (in Compressor or DVD SP) producing high quality video"

What do you think about this? Anyway, I want to follow a new way: it's not a big problem to test what you explained in your so detailed reply. ;-)

Scott, if I want to burn a Blu-Ray starting from my HDV sequence and using the "share" function into Final Cut 7, do you thing that it would be the same like starting from a ProRes one?

Regards,
Alessio


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Scott Sheriff
Re: HDV and ProRes... how to save time??
on Mar 2, 2010 at 2:00:31 am

Alessio,
That article is painting with a really broad brush. Note that they said 'some people' and not 'all people'. It really doesn't say ProRes is a cure all for everyone. So, yes ProRes is a great tool in the toolbox, but its not the only tool. Don't fall into the trap of doing what everyone else is doing, one size does not fit all. Do what gives you the best results, or solves a problem with the least amount of work.
A lot has to do with the GOP structure, if your footage is interlace or progressive, the color space, the image sensor (CCD vs CMOS), if the sensor is full raster or not and the content such as fast motion, sharp edges, patterns, applied FX. All these variables when added together in different combination can influence how your footage looks after it gets compressed, and/or transcoded. And even then, whether doing it one way, or another produces a 'better' image is subjective in a lot of cases.
That is why running a series of short tests would be best.

BluRay is a whole different game compared to SD. Maybe a real expert will jump in on that. I don't have much experience on BR.

Scott Sheriff
Director
SST Digital Media
http://www.sstdigitalmedia.com


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Alessio Gemma
Re: HDV and ProRes... how to save time??
on Mar 2, 2010 at 9:39:08 am

Thanks Scott,
your support is very appreciated.
I'll run some tests, keeping in mind what you told me.
Alessio


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