Just got my DVX100a and I need some help!

J

JediLee

Member
OK I just got my DVX100a a couple of days ago and I gotta say...man does this thing kick
@$$!!! I'm blown away by the quality!

Anyway, my question is:

I want to shoot a short film, edit the film in Final Cut Pro HD, then burn it to DVD for viewing. Should I shoot 24p or 24pa? What kind of settings should I use when I start up FCPHD? And when I burn to DVD I use Compresser to create an Mpeg2 and Audio file, but how do put those two together? I'm confused? Any suggestions?
 
Well, you have to understand the difference between 24p & 24pa before you can decide on which medium you want to run with.
You might be able to find your answers regarding FCP here

And for the DVD stuff.... Well, I'm just not there yet.
 
http://www.adamwilt.com/24p/index.html

http://www.adamwilt.com/24p/index.html

How is 24p recorded? What's the difference between 24p and 24p Advanced?


The camera can capture interlaced footage at 59.94 fields/second or 29.97 frames/second ("60i"), 29.97 progressive-scanned frames/second ("30p"), or 24 progressive-scanned frames/second ("24p").

The recorder (and indeed all the video I/O) runs at 29.97 frames/second, interlaced, all the time, regardless of what the camera is doing.

When the camera is running in 60i or 30p, the incoming video is placed into a frame buffer, compressed with the DV codec, and written to tape and/or sent out FireWire. That same frame buffer feeds the analog outputs, one field after the other. Whether the images come in interlaced or progressive, every 30th of a second – well, every 29.97th, but let's keep it simple for now – an image gets written to the frame buffer, and an image gets played out: two fields compressed as a frame for FireWire and recording, and two fields sent out one after the other for interlaced analog I/O.

24p is a bit more complex. [Of course, it's really 23.976p, the same way 30p is really 29.97p and 60i is really 59.94i, and even those numbers are approximations. When the National Television Systems Committee added color to the existing monochrome standard in 1953, they had to fudge either the picture frequency or the audio subcarrier frequency by one part in a thousand, to keep the color subcarrier from interfering with the sound subcarrier. Sound won; NTSC pictures now run at 30 * 1000/1001 fps (and that number is exact), and ensuing generations have had to struggle with the peculiarities of drop-frame time code and resetting their master clocks every day to account for drift. But I digress...] 24 does not fit so cleanly into 30; for every four frames of 24p video that go by, five frames of 30p (or 60i) video go by. Another way to look at it is that 24 frames of 24p video have to be squeezed, stretched, and mashed into 60 fields of NTSC-compatible video; that's four frames of 24p per ten fields of 60i.

There are several ways to do this; the AG-DVX100P and AJ-SDX900 offer two: 24p, which I call 24p Standard, and 24p Advanced.

24p Standard utilizes the same 2:3 or 3:2 pulldown cadence long used to transfer 24fps film to NTSC video. The first 24p frame is written to two fields of 60i video, the next is written to three, the next to two, and the next to three again, as shown in the graphic.

This cadence offers the smoothest possible raw conversion between the frame rates, and gives us the familiar judder of film transferred to tape. There are a couple of things to notice about it:

1) The "A frame" is defined as the only frame of 24p that occupies exactly one whole frame of 60i video with no overlap into adjacent frames.

2) The A, B, and D frames can be recovered by using two fields from the same 60i frame. The C frame cannot be; it is split across field 2 of the third (green) 60i frame and field 1 of the fourth (magenta) 60i frame. In an intraframe-compressed format like DV, that's an important distinction: the two fields of each 60i frame are compressed together, as a frame. If the two fields are very similar, as happens in the red, yellow, and blue frames, the compression uses a comparatively efficient "8x8 DCT" mode. If the fields are very different, as happens in the green and magenta frames when there's a lot of motion between the B, C, and D frames, a less efficient 2x4x8 DCT is used, possibly leading to more image degradation in those frames compared to their red, yellow, and blue companions.

Furthermore, the original A, B, and D frames can be copied in their compressed form from the 60i video data into a new 24p data file, but recovering the C frame requires decompressing the green and magenta frames and recompressing them into a new, 24p DV frame. That puts the C frame a generation down compared to A, B, and D.

If the 24p extraction tool uses white instead of superwhite codec ranges, as Cinema Tools does, it will clip whites in doing so – you really have to preprocess all your footage prior to reverse telecine to pull superwhites and saturated colors into range. Note that this is not necessarily an indictment of such tools: codecs that run in a white-only range instead of a superwhite range can eke a little bit more quality out of the in-range image, at the expense of the out-of-range data. However, if you're using the extended dynamic range that superwhites give you in acquisition, it means you have to add that extra processing step to pull your superwhites back into range before converting to 24p, lest the conversion hard-clip your C frames and remove that creative control from your domain.


24p Advanced uses a syncopated 2:3:3:2 pulldown cadence to stuff 24 frames into 60 fields. It's ever so slightly different in its playback; the standard cadence of 2:3:2:3:2:3:2:3... evenly intersperses the "short" and "long" frames, while 2:3:3:2:2:3:3:2... lumps two "short" frames together followed by two "long" frames. The difference is subtle, but can be seen on smooth pans or on regular in-frame motion, like the passage of a train. In my experience so far, about half the people looking at a 24p Advanced clip can see that the motion is a bit different, and half cannot.

But 24p Advanced isn't intended for making the 60i video look like film; it's designed to allow the best possible recovery of the original 24 frames. You'll note that all four original frames can be recovered from self-contained 60i frames; the green frame in 60i now contains the "extra" B and C fields and can be discarded, since all the information for B is contained in the yellow frame, and all the information for C is in the magenta frame.

Extracting a true 24p clip from a 60i recording simply requires copying the raw data for the red, yellow, magenta, and blue frames into a new 24p file, skipping the green frame altogether. No decompression or recompression is required, and all recovered 24p frames retain first-generation quality. No clipping or other loss is incurred; you are still working with all your frames in their first-generation glory in 24p.

Indeed, Cinema Tools goes one step farther: it gives you the choice of either creating a new 24p file, or simply rewriting the Quicktime frame pointers in the original file to skip over the green frames! Rewriting the header is much faster (not that Cinema Tools is slow in writing a new file), but your "new" 24p file is about 25% larger than it needs to be, since it still contains the discarded frames, and you can no longer go back to that file and play it as a 60i file: Cinema Tools has no "undo" for rewriting the frame pointers.
 
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