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Nx 70: Files are huge!

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Paul McBride
Nx 70: Files are huge!
on Sep 20, 2011 at 1:32:25 pm

My Church recently purchased an NX 70 for the purpose of recording and online posting services. However there has been an issue with efficiency as the files seem to be very large coming in at about 10 gigs of only about 40 minutes of recorded time. This has made bringing files from the camera in to final cut almost a 5 hour process! We lowered the definition from HD to SD since the picture quality is still quite good, but it did nothing to the loading time of the files, and they were still very large. Does this seem like a computer processor issue, or is there another way to make the files smaller? We're running through either a macbook pro, or a 2 year old iMac, both which can usually handle HD files fairly well.


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john lenihan
Re: Nx 70: Files are huge!
on Sep 20, 2011 at 2:09:43 pm

When I shoot a three hour event, my nx5u file comes in at 30 gigs, so yours seems in the ball park.

Remember, in the olden days, minidv tape took up 13 gigs per hour.

When you say, comes in, do you mean the original m2ts file from the camera, or after it is converted to mac pro res?

Although I am not a mac person, I have heard there are more than one way to convert to the mac format, which will affect its size.

But size of file should not be your problem, just buy a bigger disk.
The more expensive problem is that editing the HD compressed as avchd takes a lot of computer power. Editing the SD, which the camera compresses as mpeg2, takes less computing power, although the file size will be about the same because it is compressed less than avchd.

John Lenihan

LeniCam Video Productions
http://www.lenicamvideoproductions.com


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Ian Cook
Re: Nx 70: Files are huge!
on Sep 20, 2011 at 3:08:49 pm

Hi Paul-

The NXCAM files are actually quite small. When you import to FCP it does an automatic conversion to ProRes 422, which takes the 24 Mbps files and turns them into 200+ Mbps files. It's normal for the conversion to increase the file size by almost 10x.

We can't do much about the processing time. Make sure you are using 7.0.3 if your clips have PCM audio. There was a bug in previous versions of FCP that caused files with non-Dolby audio to take roughly 10x longer than normal to convert due to errors reading/processing the uncompressed audio.

FCP X creates smaller files in less time as it only re-wraps to QuickTime and does not convert the video.

Hope this helps..


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Don Huckleberry
Re: Nx 70: Files are huge!
on Oct 5, 2011 at 4:08:45 am

To the lay person, 13GB/hr sounds huge, but that is actually very small compared to other compressed formats or even uncompressed standard def video as Ian alludes to.

The AVCHD codec that the NX 70 uses can go up to 28 megabits/sec (spec page from Sony), going down to SD it will go to a fixed 25 mb/s (I am assuming it's just the DV25 codec) - so you don't really save much and the picture quality suffers - in the time from the "invention" of the DV codec till HDV/AVC, technology advanced rapidly and the higher quality is being squished down to a manageable bit rate. Look at these data rates to scare you http://en.wikipedia.org/wiki/Uncompressed_video

I am not familiar with the AVCHD --> FCP workflow, but it appears that it uprezzes footage (maybe by default and you might be able to change that) during a transcode to get it to ProRES. Like Ian says - I think that FCPX "fixes" that by allowing you to access the native file in a file wrapper (sort of like how a .mov can be on of compressions an configurations, but they are all still playable by QT player).

The files will never be as small as "output" .mp4/h.264 files - you want and need more data than that to edit with to retain the quality and even AVC is extremely compressed already (reference the link above to compare the data rates). Fact is, AVCHD is a long gop type of h.264 and is already extremely lossy - that's why FCP wants to uprezz it to ProRES.

You need more disc space and create a good workflow that allows you to copy only what you need and archive the project when done. You may also want to look into Avid Media Composer and Adobe Premiere if you are not in love with the move to FCPX and FCP 7 is causing you trouble.

Good luck, keep us informed plz.

Don


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Stephen Crye
Re: Nx 70: Files are huge!
on Nov 3, 2011 at 6:58:50 pm

Hi;

I find that for most causal shooting, 1920x1080 17 Mbps HD-FH mode at 60i is very workable, and results in files that are a lot smaller than the 24 or 28 Mbps HD-FX (either 60i or 60p). For *very* casual stuff, 1280x720 is often good enough and is a LOT smaller.

Hope this helps, good luck!

Steve

Win7 Pro X64 on Dell T3400 MultiTB SATA 8 GB RAM Vegas 10e x64 DVDA 5.2 Sony HDR-CX550V


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