DV Info Net - Strange Architect Issue Please Read

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Quote:

Originally Posted by Jason Robinson (Post 876526)

I'll explain exactly how this difference matters.

Thanks Jason. Great (and simple) explanation!!
This one gets added to my archives for the next time someone asks "why doesn't my DVD fit?"
:-)

Quote:

Originally Posted by Mike Kujbida (Post 876188)

Renton, in case you didn't know, you're adding another level of codec transformation by doing this and therefore dropping your image quality, particularly on all stills and generated media (like text).
DV-AVI has a 4:1:1 colour space, stills and generated media are 4:4:4 and MPEG-2 is 4:2:0.
See Adam Wilt's site here and here for a good explanation of these numbers.
When you render to AVI and then to MPEG-2, you're going from 4:4:4 to 4:1:1 and then to 4:2:0.
By rendering directly to MPEG-2, you're going from directly from 4:4:4 to 4:2:0 and bypassing the intermediate codec transformation loss.

Now that I didn't know! I always believed that rendering to avi meant rendering uncompressed - I don't think I'm alone here. But your colour space explanation makes great sense and could explain some unexplained quality loss - especially in text. Many thanks.

Ian . . .

Quote:

Originally Posted by Mike Kujbida (Post 876550)

Thanks Jason. Great (and simple) explanation!!
This one gets added to my archives for the next time someone asks "why doesn't my DVD fit?"
:-)

I knew those CS sources would eventually come in handy. :-)

But seriously, this becomes a headache the larger storage systems get. Users need to look at a storage device and then automatically throw out 7% because of the battle in nomenclature. THEN you need to throw out another 2-5% because that will be used by the partition table to store & organize all that data. Then you throw out some more due to the unused sector issue that another poster mentioned above (though this is less of an issue with large files and more a problem for drives containing lots of files below 16KiB in size).

Pretty soon, that 300GB hard disk is actually only giving you the ability to use 270GB worth.

Quote:

Originally Posted by Ian Stark (Post 876565)

I always believed that rendering to avi meant rendering uncompressed - I don't think I'm alone here. But your colour space explanation makes great sense and could explain some unexplained quality loss - especially in text. Many thanks.

Glad to have been of help Ian.
DV-AVI (and HDV footage too, for that matter) is approx. 13.5 GB/hr. while uncompressed AVI is approx. 90 GB/hr.
When you think about it, a (single layer) DVD only holds 4. 3 GB so there's a whole lot of compression going on to shrink files down that much and colour information loss is one area where that happens.
Now you know why a DVD can never look as good as the original source footage.
I personally find it amazing that a DVD looks as good as it does, considering the huge amount of compression it has to go through to get there.
Life was so much easier back in the "old days" of videotape when you went from source tape(s) tape to edited master tape.
No codecs to confuse you at every step of the process :-(
BTW, it's nice to see someone else who knows how to spell "colour" correctly :-)

Quote:

Pretty soon, that 300GB hard disk is actually only giving you the ability to use 270GB worth.

Windows says my 500GB. hard drives are only 465.76 GB. so you're not too far off.

Quote:

Originally Posted by Mike Kujbida (Post 876607)

Windows says my 500GB. hard drives are only 465.76 GB. so you're not too far off.

That was rough estimation after the 7% drop due to number confusion. But isn't it amazing how that starts to be a substantial drop in storage. I mean, that is almost an entire project's worth of material from a single camera wedding for me. Let alone the 11hrs of footage from my most recent wedding.