Working with DSLR and AVCHD files, transcode?

[Chris Borjis]

[Garrett Lynn] “So with Adobe, you would keep your capture scratch on the raid and that would do the trick?”

Ya, I set the renders/previews/captures and scratch to the raid.

plays/renders much faster that way.

You might be able to just get another of the same drive you’re using
then back it up, add the other drive and create a RAID zero with
windows disk administrator or whatever its called these days.

[Garrett Lynn]

cool thanks! Which RAID drive should I get for PC??

[Angelo Lorenzo]

Good to know.

Did a bit more testing and it seems that if size matches, it carries over the framerate regardless of the framerate setting

If you mismatch the size, then it will also resample the framerate if you’ve selected the wrong framerate as well.

I compared original to a few mismatched renders by putting down two video layers, with one of the two clips set to a blending mode of “difference”

I never caught this because I always render out 1080 @ 220x from 1080 source material.

Angelo Lorenzo
Fallen Empire Digital Production Services – Los Angeles
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[Chris Borjis]

ideally 7,200 rpm at the minimum.

if the one you are using for storage is already at that speed, I’d just
grab another one, then use them both for the RAID zero.

back up your data, create the RAID set, then copy it back.

playback should be much smoother.

[David Fuku]

I’ve been using a mac laptop with SSD and 16gb of ram 2.4 i7 and I noticed with esata SSD as my scratch I use the aja disk test and internally I get 250 write 450 read and on ssd / esata 3gb/s controller (enclosure and esata express card) I see 85 write 106mb/s read. I have to have the program monitor on 1/4 qty and 25% viewing to have reliable normal to 16x scrubbing speeds.

You might consider trying to lower those settings and see if this helps. I just bought an imac with the faster 6970 amd opencl with 2gb ram on that card but I have the 1tb seagate 7200rpm which I think is actually slower for scrubbing but my imac is fw800 for a while longer and that only shows 35/50mb/s read write

I’m working on a project with avchd/mts files and have done avchd/dslr Canon projects

[Casey Stormes]

HOw can compressed files from my DSLR become uncompressed when they are converted to ProRes? It seems like once a video is compressed, you wouldn’t be able to get that information back.

[Walter Soyka]

[casey stormes] “HOw can compressed files from my DSLR become uncompressed when they are converted to ProRes? It seems like once a video is compressed, you wouldn’t be able to get that information back.”

Compressed encoded video cannot be directly processed, because until it is decoded, it is really just data and not an image at all. Thus it is always decoded first before processing or display. There is always an “uncompressed” stage for any video operation, if only in the computer’s RAM, when working with compressed video.

In the workflow above, transcoding from your DSLR footage does not restore original detail lost in the H.264 compression. It decodes each frame of your H.264 source to an uncompressed image buffer in order to encode that to ProRes. Detail lost during acquisition cannot be regained; this uncompressed buffer will contain whatever visual loss and compression artifacts were present in the H.264 source. The ProRes encoder will attempt to preserve those artifacts (thinking they are “detail”), and it will add its own subtle (and often unnoticeable) artifacts as well.

ProRes is significantly heavier than most H.264 in terms of bitrate/file size, but it’s significantly easier for the CPU to decode in realtime. It can provide a more fluid editing experience — especially for larger resolutions or on lower-spec systems.

Walter Soyka
Principal & Designer at Keen Live
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