import/export compression 101?

vernallis

vernallis

Member
if this question is down right too open ended
i plead no contest,
but i have to ask....



for years when i have been capturing my dv footage
i have been assuming that how final cut was importing it
was at its "highest resolution"


(i ashamedly admit that it wasn't until i started shooting 24pa
that i even new that i had options of ways to import...)

what i am wondering,
(and i'm not talking about hd for the moment,
or about timelines framerates)
is if you are importing your footage as normal? "dv ntsc"
rather than lets say dv50 ntsc
are you compromising the full resolution of your footage.

basically,
what is the "purest" way to get what you have on tape
onto disk.

and in the reverse.
would exporting "uncompressed 8 or 10 bit"
be that much better than dv 50.

i know there are oddles of ways to export for different reasons.
at the moment i'm just wanting to know,
if you want to capture, edit, and then export with the least loss due
to compression,
what would that be?

thanks for thoughts-
 
If you shoot DV, it is compressed 5:1 on the tape. You can't avoid that, that is just how it works. When you capture that footage using the DV/NTSC Easy Setup, you are capturing it at FULL RESOLUTION...it is a simple data transfer from the tape to your hard drive. NO LOSS.

DV50 is the codec for DVCPRO 50 cameras. You need to shoot DV50 in order to use this codec for capturing.

Uncompressed 8-bit and 10-bit, while still compressed, are much less so. You use these settings for capturing footage like BetaSP, or digibeta...high end analog formats.

OR, with the use of a capture card and a deck with appropriate connections, you can capture your DV footage as DV50, or Uncompressed 8-bit or uncompressed 10-bit. Will this improve the quality of your footage? No. The footage is already compressed on the tape. You have now captured it using another compression so technically it is at a LOWER quality than if you captured straight DV/NTSC.

Why do people capture footage uncompressed? Because of the better color space for doing color correction. DV is a 4:1:1 color space while uncompressed is 4:2:2...you get more information. Color correcting in uncompressed codecs allows for better color control and less degrading of the source image after you render.

SO, if you shoot DV, capture DV/NTSC, edit and then output back to DV tape...NO COMPRESSION will have occurred. But, if you add filters or color correct, slight loss will occur.
 
Shane one question from your posting...

Why would using a different (non DV-NTSC) codec as your digitized degrade your footage? I can understand if you use a capture card and use its component option, but not if you use SDI. So say you capture your DV25 (with its inherent 5:1 compression) at DV50, is it now going to re-compress ontop of that using DV50's inherent compression? I know what you shoot is what you get so you can't invent quality, but figured even if using a different codec it was "smart" enough to not recompress (just digitzed differently to allow for the better color space for titling and cc'n).

cheers.
 
VaricamLife, you hit a very good point. For optimum image quality, stick with the format you shot on.

Color grading is a reason for using a better color space codec, but only if you're a professional colorist who knows what you're doing. You won't "add" any information to the footage you're grading, you just have more room to play with what's already there, but not by a great deal. You're still working with only the data that was recorded.

It also allows for higher res grahpics to be brought into the Timeline without any more quality than nessisary.

But if you're not getting into super high end features, just stick with the codec you recorded with.
 
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