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Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080

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Isaac Brillant
Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Dec 31, 2009 at 7:17:42 pm

Hi,

I saw a post from last year by Noah Kadner, about transcoding to Prores vs DVCProHD... I'm hoping you (Noah) can clarify this for me, since you seem to be the expert on this topic

I spoke with CINEFORM and others, and it seems that I wont be able to maintain consistent timecode if transcoding from AVCHD to ProRes (unless I invest in a KONA card, at which point I may as well spend that money on an HPX or HVX. And I work on a MacBookPro so I dont think I can install a kona).

The reason I had wanted to do this was to save storage space when media managing the project, in that I could trash the unused ProRes clips and if I needed them later, REDIGITIZE them from AVCHD.

But it occurred to me that maybe I could accomplish the same goal by transcoding to ProRes LT in either 720x1280, which according to the ProRes white paper is 18 GB/Hr, OR 1440 x 1080 which is 31 GB/Hr. This is compared to standard" ProRes at 1920 x 1080 which is 53 GB/Hr.

Since the HMC150 is shifting pixels and all that, and isn't native 24p (I think) and is already very compressed, am I really losing anything by transcoding to ProRes LT in 1440x1080 or 960x720? Am I right in thinking that I may even get a better quality by shooting in 1920x1080 and then transcoding it to one of the above?

Another route I thought of is to capture to standard ProRes at 1920x1080, and then when I archive the project, transcode all the unused "standard ProRes" to ProRes LT at 1440x1080 or 960x720. (Then if I have to re-digitize at some point, I'll live with having to blow up the clips to a larger size or bring my other clips down to a lower res, since I'd probably finish in one of the smaller sizes anyway.)

Are either of these viable options, or am I missing something? And will transcoding from ProRes 1920 x 1080 to ProRes LT 960 x 720 maintain timecode since it's the same codec?

Lastly, is there any loss in quality transcoding from AVCHD --> Prores HQ 1920x1080 --> ProResLT 960x720 vs. transcoding straight from AVCHD --> ProResLT 960 x 720?

I'd be very grateful if someone could clarify this for me.

Thanks! Happy New Year. I'd love to solve this problem in 2009!

Isaac


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Alf Hanna
Re: Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Dec 31, 2009 at 11:16:55 pm

Huh. I'm a bit confused. I understand what you are saying about the timecode issue, and hope that it's not a correct assessment. But the Kona card is a capture card. Are you saying that you need to output the AVCHD through the camera out to the capture card, instead of simply taking the file structure off the card and into a Mac filestructure???? That seems odd.

So what I do understand you to be saying, is that my timecode based video from my HMC-150 will not maintain TC sync in Prores??? Would I (or you) be better off simply paying to go to Adobe instead????

Looking forward to the answer as well!

Alf
Panasonic HMC-150 & Vegas Video 9.0c on Win7/64bit


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Isaac Brillant
Re: Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Jan 1, 2010 at 1:08:00 am

"So what I do understand you to be saying, is that my timecode based video from my HMC-150 will not maintain TC sync in Prores??? Would I (or you) be better off simply paying to go to Adobe instead????"


Hi,

Right. It won't maintain the timecode. I'm not an expert at all, but based on the research I've done I'll try to answer:

Someone else on a thread said that I'd need a capture card if I wanted to consistently maintain timecode when going from AVCHD to ProRes. And the people at Neoscene also told me that in their test the AVCHD from the HMC150 didn't maintain the timecode in Prores. If you only plan to do that conversion once, and then stick to Prores and archive the Prores files, then it makes no difference. But if you ever plan to redigitize from the AVCHD files, then it would be an issue.

But, even though right now it seems like you'd need a capture card to do it, in a few months, there will probably be some way to do it with software like Neoscene. So I guess it would just pay to hold onto any of your transcoded Prores files that you think you might possibly ever need, and your AVCHD files until they come out with a software solution. And then when they do and you're able to dump your unused Prores footage, you'll find yourself with a lot of new space on your harddrive.




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John Christie
Re: Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Jan 1, 2010 at 6:43:54 pm

Hi Isaac

Haven't done my definitive capture and re-capture test yet. But I can assure you that the Prores files do contain the timecode from the original AVCHD files. Panasonic wouldn't be able to sell a semi-pro system with out timecode.

I've aso used a small Sony handicam type AVCHD camera. That camera didn't have timecode that followed through to FCP. Every clip started at 00. So maybe that's where you're getting conflicting info from. Not all AVCHD has timecode.

Cheers

John C


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cowcowcowcow
John Christie
Re: Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Jan 1, 2010 at 9:49:53 pm

Hi Isaac

Read the answer to your other post about re-capturing from AVCHD, it all works properly as it should.

Don't use Prores LT as a final codec, it's designed for offline editing. You can import everything as LT for space reasons, and then media manage and recapture your final timeline as Prores or Prores HQ. You won't notice a huge difference between the two unless you're doing a lot of graphics work.

You don't want to be transcoding and changing frame sizes and frame rates, things will get ugly real fast. Pick a frame size/rate that fits your needs and stick with it. I like 720P as I can shoot 24P or choose to shoot 60P for nice slo-mo footage. But that's my choice.

Cheers

John C


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Isaac Brillant
Re: Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Jan 6, 2010 at 11:51:06 pm

Hi John,

Regarding holding on the AVCHD files for archival - a B&H sales person told me that you can't delete individual junk clips from the AVCHD folder, as you might do with P2 clips. Not just "in camera," but also when it's on your computer. Is that right?

Thanks again


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John Christie
Re: Transcoding from AVCHD (HMC150) 1920x1080 to ProRes(LT) 960x720 or 1440x1080
on Jan 7, 2010 at 9:33:56 pm

Hi Isaac

That is correct, you have to keep the whole file structure in the PRIVATE folder intact. You can delete clips while the card is in the camera as the metadata will be correctly updated.

Cheers

John C


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