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Proxy workflow in Avid MC

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Rachel Pearl
Proxy workflow in Avid MC
on Oct 5, 2017 at 1:25:45 am

I have a question for a student of mine who wants to cut using a proxy workflow in Avid to save drive space.

They've shot a project and want to cut it in Avid. The files are 1080 h.264 and they want to import it into Avid as 1:1. But.. the files are too big for them.

They want the files to be smaller but keep the quality as high as possible. Is there another compression that might work?

Are there any proxy workflows in Avid to cut it at low resolution and then match it back later?


Thanks!

Rachel


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Brent Marginet
Re: Proxy workflow in Avid MC
on Oct 5, 2017 at 3:00:39 am
Last Edited By Brent Marginet on Oct 5, 2017 at 3:17:54 am

Can you supply more info about the H.264 Files.
What Frame Rate, Bit Rate and so on.

Is there any reason why they can't just AMA Link these files and cut with them as is or is the system not able to play them back properly.

Importing the files at 1:1 really isn't going to accomplish anything except using a ton of hard drive space. These H.264 files are compressed so the quality is not going to get better by importing them as 1:1. If they can't use them as is AMA Linked then AMA Link them and Transcode them to one of the DNxHD Codecs. Just so you know most of the Codecs you would Transcode to will still likely be larger than the original media. Most Camera's that record to H.264 use bit rates of about 20 to 50mbit and generally no more than 100mbit. If the originals are 10bit and 23.976fps and you were to Trancode to DNx175x to keep it 10 bit then as you can see they will end up being larger than the original media. These cameras can record at these lower bit rates because they use Long GOP Codecs were as Codecs like DNxHD and ProRes are not.

Will try to help more once I know more about the original media.

"MY MEDIA/PROJECT MOTO: If you think three copies of your media or project are enough.
Take a moment to place a value on them and then maybe add two more.
Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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Shane Ross
Re: Proxy workflow in Avid MC
on Oct 5, 2017 at 7:12:23 am

[Rachel Pearl] " The files are 1080 h.264 and they want to import it into Avid as 1:1. But.. the files are too big for them. "

1:1 is overkill. Not sure who uses that anymore, the data rate is so high it takes extremely fast hard drives to play back. DNxHD is a good choice, as it is a compressed format, but near lossless. it's the standard that pretty much everyone in broadcast TV works in and delivers.

[Rachel Pearl] "They want the files to be smaller but keep the quality as high as possible. Is there another compression that might work?"

DNxHD 175...or 145, depending on the frame rate they shot. Or you can go to 175x, that's a 10-bit format, although the H.264 masters are 8-bit, so staying with 8-bit DNxHD (which 145 and 175 are) is fine. Those are typical formats that we use for mastering.

[Rachel Pearl] "Are there any proxy workflows in Avid to cut it at low resolution and then match it back later?"

Avid INVENTED the offline/online workflow. Simple AMA link to the footage, transcode to DNxHD36 (to a separate drive than the camera originals), or if you need it even lower, 14:1. Edit, lock picture. Then duplicate the sequence and then take the media drive offline...connect the camera raw drive, open the bins with the AMA linked originals and the select the sequence and choose to RELINK to all open bins. There are tutorials that explain this.

Shane
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Read my blog, Little Frog in High Def


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Michael Phillips
Re: Proxy workflow in Avid MC
on Oct 5, 2017 at 12:39:49 pm

A LongGOP format such as H.264 will always be less space than the same file in an I frame format like DNxHD or ProRes - it's the nature of the encoding formats. You can google a bunch of info on that if interested.

for 1 hour of footage @ 1080p/23.976, DNxHD storage rates are:

DNxHD 36 (offline proxy): 15 GB
DNxHD 115: 49 GB
DNxHD 175/x: 74 GB

Michael


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