-
24p vs. 30i DVDs
From reading Sony’s literature, I got the impression that if you were to take 24p DV footage (say, from the DVX-100, 24p Advance), and keep it 24p throughout, that your final 24P DVD Architect stream would be roughly 2.5 times smaller than a regular 30i DVD Architect stream of the same length. But my test renders haven’t shown that to be the case. Did I misread Sony’s stuff? Or is there a problem in the way I’m rendering my DVD-Architect .mpg streams?
Sony very clearly stated that 24p projects should render about 2.5 times quicker than 30i projects (40% as many fields to render). I have found that to be fairly close to the case, but the size of each is nearly identical. Any thoughts?
Thanks!
Marc
-
5 Replies
-
Hi, just a think:
24 fps video contains 24*720*576 pixels in a second,
that’s 9953280.
30 fps video contains 30*720*480 pixels in a second,
that’s 10368000.
That makes approx 4% difference in my calculation…By(t)e
Laca -
Thanks for the response…
That totally makes sense. But it really seemed like Sony’s literature insinuated that you could fit more video (not just 4% more) on a DVD if it was 24p. Maybe I just read it wrong.
Thanks again!
Marc
-
You are only calculating the difference of PROGRESSIVE frames. Video contains TWO fields so that’s 60 images per second for 30 fps interlaced video. For 24P, that’s only 24 images per second. It takes 60% less processor power for 24P footage.
File sizes:
If you are writing out 24P DV files, they are the same size because it is actually writing out 29.97 with the Advanced pull-down, so that only the 24 Progressive frames can be extracted.Where you should check your file sizes is with the MPEG2 files. When you export 24P MPEG2, then it is truly only 24 images. Your DVD player will expand the 24P out to 29.97i for your TV monitor.
td
-
Timothy — you’re right. I know the DV files should be identical in size. But the DVD Architect streams are mpeg 2, no? I shot 24pA, removed pulldown, used a Vegas 24p project and rendered with DVD Architects 24p stream and it’s nearly identical in size to the same project rendered with interlacing added back. Any thoughts?
Thanks!
Marc
-
———-
>You are only calculating the difference of PROGRESSIVE frames. Video >contains TWO fields so that’s 60 images per second for 30 fps
—-
Definitely yes, but these are not full frames, just half frames.
Not 30*720*480, but 60*720*240 for a second. (One field contains a 720*240 half-frame).
Finally, it makes the same pixel amount.Am I wrong?
By(t)e
Laca
Reply to this Discussion! Login or Sign Up