                 
|
director of photography, peter gray, dp, cinematography, dop, cinematographers, lighting cameraman, videographers, dv, high definition, 24p, digital films, HDW-F900, CineAlta, Varicam, AJ-HDC27F, 70mm, independent films, lighting directors, filmmakers, filmmaking, HDW-700AInitial Reaction to Release of 24p mini-DV
I've been checking into the new goodie's being released at NAB this year (April, 2002). There is an interesting new development in the digital camcorder world. After years of rumors and speculation, 24 frames-per-second progressive (24p) in the mini-DV camcorder format is becoming a reality. The first 24p mini-DV format camera is Panasonic's soon to be released model AG-DVX100 DV Cinema(tm) Camcorder. The announced delivery date for customers in the US is late September, 2002, when a shipment of the first 500 units is expected to arrive from the factory in Japan. Here is Panasonic's press release: "Representing a revolutionary leap in digital video technology, the AG-DVX100 DV Cinema(tm) Camcorder is equipped with three, newly-developed 1/3-inch progressive scan CCDs that allow the camcorder to capture high-sensitivity images in both standard 60-field-per-second NTSC (interlace scan) and also at 24-frames-per-second progressive scan (24P), the frame rate at which many prime time HD episodics, commercials and independent movies originate. This makes the AG-DVX100 the world's first and only 24P Mini-DV camcorder." "The AG-DVX100 DV Cinema camcorder democratizes visual storytelling by substantially reducing the cost-of-entry for digital filmmakers," English commented. "The AG-DVX100 is a forward-looking tool that will allow the creative community, whether video journalists, digital cinematographers or event videographers, to express their visions at the highest creative level."
U.S. List Price: $3,495.00 Features include: World's first mini-DV camcorder to capture cinema-style 24p images
Great. Lets pop in that tape and start rolling. Wow, we are shooting 24 fps just like a film camera. And the CCD is scanning progressively, giving us better looking images. That's good. Now what? Let's play it back and take a look. But there is no 24p display system to plug it into. But all is not lost. Panasonic has designed the camcorder so it will play back on a regular regular NTSC television (as 60i). This is great, but we are not seeing 24p any more, but rather normal video with 6 more frames artificially added (the so called 3:2 conversion process). But on the other hand, this is what happens to all filmed movies we see on television. So in a sense, we are still getting a little bit of that elusive "film look". What next? Let's edit. This is possible on your home computer, but you will need the latest generations of NLE software that is designed to support 24p. So most of us will need to update there, but it is worth doing. The editing is finished, titles and sounds added ..... what next? We can play it back on our computer screen. At least there, we can see it displayed as true 24p. Or we can firewire it back out to our 24p camcorder, and show it on our television set once again (with the 3:2 conversion process added). Not bad, but are we really exploiting the potential of 24p for the home market? Time to send it out to show to other people. How will we distribute 24p mini-DV video? Well, one way is to convert it from the mini-DV compression scheme to MPEG-2 compression. This will result in some loss of quality, but it still should look pretty good. Now author it to the DVD movie format, and burn it to a DVD-R or DVD+R disk, or similar. Probably not a bad solution, but we are going to have to buy a lot more gear to make this workable. And I believe the DVD movie standard will support 24 frames a second. So we can encode it as 24fps, but most people will not have the means of playing it back at 24fps, of course. Or not on regular TV screens anyway. The DVD player will add back the 3:2 conversion process automatically, so it will display on a regular NTSC television or video monitor. Or convert it to the newer MPEG-4 compression scheme, and burn it to a much cheaper CD-R disk, or even stream it over the Internet. The quality is a little less, but almost as good as DVD. But the file sizes are less than one tenth the size for a similar level of quality. This technology is maturing rapidly, but it is early days yet. Maybe 24p mini-DV and MPEG-4 will make an excellent partnership in the near future. Significantly, chip maker, Texas Instruments, is now producing the first chip capable of playing back DivX MPEG-4 video (called DSC25). In other words, a more efficient hardware decoder, rather than a software decoder. I don't mean to pour cold water over this announcement. It is wonderful news, really. Certainly a most interesting development, but not a cure all, by any means. I don't think 24p makes much sense in the mini-DV world, unless you really, really want that type of so-called "film look", and/or you are blowing up to 35mm film for release. It will probably turn out to be one of those fads without any real practical value for a lot of people. Or at least in the beginning. But in any case, I suspect 24p will be huge - really huge. Mini-DV fanatics will get swept up with this phenomenon in a very big way. I think it will simply be irresistible to many. Wow, they can now have 24p just like the Lucas Star Wars cameras. And like I say, what will we do with their newly acquired 24 p images. How will we display them? How will we edit them? How will we distribute them? We will need a lot of new consumer-orientated, post-production infrastructure to make this new trend more viable. But no problem really. It is no big technological hurdle, and I believe we will eventually get these types of facilities in the home market in any case (......and much of it exists in various forms already). It is the way to the future, and in a way 24p mini-DV slots into the this general trend rather well. We hear so much about the so-called "film look", but there is nothing so special about 24 frames a second. Moreover, it has little to do with images per se, but more to do with sound. It was simply the lowest film transport speed they could get away with to produce acceptable quality sound using the technology available in 1926. If it wasn't for sound, then something around 18fps might have become the projection standard for film images, or who knows what??? Actually, this statement is a bit over simplified really, as there were a lot of considerations under review in 1926, and a lot of different tests done, and marketing forces at play. But I think the requirements for sound was a major part of it. So 24fps worked for sound, and it stuck. And it worked quite well for the images too. Now we are used to seeing film images flashed at us 24 times a second, and we now consider it a standard reference to judge everything else by (including video and digital images). But 24 frames per second is an incredibly slow sampling rate by today's standards, and it produces all sorts of artifacts peculiar to film. For example, blurring, skipping and strobing effects as soon as there is any sort of faster movement (subject movement or camera movement) in the image. We are so used to the artifacts of film, we don't really 'see' them anymore, or rather they are part of the film experience. And filmmakers have learnt various tricks to minimize their effect and hide them from audiences. But when you compare it to something better (i.e. a faster sampling camera), then film artifacts suddenly begin to jump out at us, and look rather ugly and old fashioned. But I do like the "p" or progressive scan part of the 24p equation. Fortunately, "24" and "p" always go together these days (in other words, I've never heard of 24i or 24fps interlaced scanning, thank goodness). Progressive scan CCD's really do look better, and I feel sure will supercede and replace all forms of interlaced video in due course. So the move towards progressive scanning is a big plus, and definitely a move in the right direction. To me, I'm more interested in the progressive scanning part of this new development, than necessarily the 24fps part of it. Actually, I understand the new camcorder will not shoot at 24p, but really 23.976p. I know this is a very strange looking frame rate, but basically a very good idea if you are working in a NTSC environment. This will make later conversions to analog NTSC video must simpler, easier, and cheaper. Converting 24p to 59.94i is very difficult technically speaking, but converting 23.976p to 59.94i (NTSC) is relatively simple and comparatively cheap. Most people shoot HD, not at 24p, but at 23.976p for precisely the same reason. I believe the available frame rates will be 23.976p (=24p), 29.97p (=30p), and 59.94i (=60i) in the NTSC environment. If you live in a PAL-based country, then my guess is that Panasonic will manufacture a true 24p model for your particular market area(?) And in addition to traditional 50i, hopefully a 25p option as well(?) What Panasonic has done is develop a video recording system that captures at 24p, but ........ (wait for it ......) records at 60i in an almost indistinguishable way from regular NTSC video. Strange but true. Something very special is going on when the Panasonic AG-DVX100 DV Cinema(tm) Camcorder records in the 24p mode. It adds a 3:2 conversion step before the data is recorded to tape. This is added at the recording stage, rather than during playback!!! This is not necessarily a bad thing, provided you can recover the original 24p frames, should you need them. Even Sony's 24p HDCAM does something like this, by using a system called "segmented frames". It is all about being able to shoot "progressive" frames, while still using the huge "interlaced" infrastructure that exists already (especially for post and broadcasting processes). So each frame can behave like a true progressive frame, but at the same time can still work with regular interlaced equipment. A very clever trick in a way. You are introducing a brand new format to the world (i.e. 24p HD), but without having to completely change the wider equipment support-base overnight. It seems the same concept applies to the Panasonic 24p mini-DV camcorder as well. After capturing the 24p video, the Panasonic camcorder processes the information further by adding the 3:2 process, before recording everything to tape. The resulting recording is effectively the same, or technically the same, as regular 60i NTSC video. Note that this is happening in the recording stage, rather than the playback stage. The camcorder takes each frame it captures from the progressive CCD's, and splits the even lines off to one field, and the odd lines off to another field, and then records those 2 fields to tape as if it was an interlaced signal all along. Then in an alternating fashion, the camcorder duplicates one of those fields according to the 3:2 pulldown structure (see diagrams below). It duplicates one field, and records 3 field in a row, then 2 fields, then 3 fields again with an extra field artificially added, then the normal two fields in an alternating sequence like this. Note the 3, then 2, then 3, then 2 progression ..... hence the name 3:2 pulldown, or the 3:2 process. Four of the 24p-frames are processed to make five regular NTSC-video frames (or more correctly, ten NTSC-video fields). So the original 24p video effectively becomes 60i video, but with a 3:2 process added. This video can then play, without any further processing or conversion, on regular interlaced DV gear. The advantage of this approach is complete compatibility. 24p mini-DV tapes will work with ALL existing DV equipment out there, including editing systems etc. Now, that's clever thinking. In lieu of making a new standard, Panasonic can introduce what is effectively a new format to the scene, without having to provide all the other infrastructure at the same time. Dedicated 24p facilities can be introduced to the market later, as they are developed and refined. By using additional software support (called "pulldown detection") the recording can be converted to true progressive video if, or when, needed. The two artificially-generated fields can be recombined to make a true progressive frame later, if you choose to do so. The original 24p frames are "tagged" during the recording, so they can be identified and recovered later in post. So an additional process using software, is required to recover the original 24 progressive frames if they are needed for 24p editing, or for distribution as 24fps on a DVD disk etc. By the way, un-doing the 3:2 conversion process, is sometimes called Inverse Telecine (IVTC). So for true 24p applications, special software is being written that 'understands' the added 3:2 pulldown process. Apparently, the Panasonic 24p camcorder puts data-markers in the DV data stream to mark the split frames where the extra fields are added by the 3:2 process. In this way, this special software can discard the extra artificially-generated fields which were added during the 3:2 process, allowing native 24p editing. I understand this can already be done using Adobe After Effects. I also hear Apple is adapting Final Cut Pro to perform this operation as well. It looks like the new 24p camcorder is going to compete in the Sony VX2000, Sony PD150, Canon XL-1s, general market area. This is very much the "prosumer" market. Not quite amateur, not quite professional, or combines elements of both. Of course, a certain number of new users will try to employ this technology for a more or less professional application, like feature film production, or for broadcast. It is great that this is possible. It is a delicate balance between the technical limitations of the format, verses its low-cost, ease of use, and flexibility. This makes certain types of production possible, that were not possible before. This has to be a good thing. When it comes right down to it, all this is basically a very good trend. I applaud the general move that pushes even the mini-DV world towards 24p capture. It all helps to create an interesting and viable path towards inevitable future technologies. The trend is towards digital imaging, progressive scanning, variable frame rate, and higher and higher levels of image and sound quality at a cheaper price. Of course, for the mini-DV producer interested in 35mm releases, it is probably going to turn out to be a great bonus. I'm just not so sure of the real benefit to the rest of that particular consumer or prosumer market, or at least not in the short term. They might even continue shoot at 60i, and not slide the switch over to 24p perhaps? But it will be a nice feeling that their camcorder can do it at least!!! Or shoot 24p, even though it will look a lot like 60i video anyway. But having that 3:2 conversion process automatically added to their 24p images will make a lot of people very happy indeed. Anything to get away from the traditional "video look", and a little more in the "film look" direction. But mini-DV 24p is potentially very good for the low-budget producer interested in film prints for a theatrical release. And 24p should make things easier on the audio side of things as well, when converting digital video to film. Although, strictly speaking, it is not really about sync issues as such. When converting video sound to 24fps film, they usually slow down the sound to keep it in sync with the new film images. This produces a change of pitch of the sound track which you can usually hear (especially with music). You can further process this sound in a computer to correct for the change of pitch, but this is a more expensive and complex process. So if you shoot your digital video at 24 frames per second (or 23.976 fps), then you can make a direct conversion to 24 frames per second film. This is true of both the images and the sound. So this should makes things easier and cheaper ...... and much simpler and better overall. Generally speaking, the quality should be better, and the conversion process cleaner and more straight forward. Also because the digital video is already progressive scan, then you don't have to do the extra process of converting your interlaced scanned video to progressive scan so you can print it to film. This is a tricky conversion process, and tends to produce artifacts to degrade your image further. It is difficult to combine two dissimilar fields that were captured at slightly different moments in time, especially where there is motion (subject or camera). So the 24 fps combined with "progressive scanning" is a great bonus for converting digital video to 24fps film. And no 3:2 conversion process either, in other words, dropping 12 fields out of an original NTSC recording. So like I say, very good for the mini-DV producer interested in converting to 16mm or 35mm film for a theatrical release. And I applaud the inclusion of standard XLR inputs for the audio. This will make sound recordist very happy indeed. Standard connectors and cables can be used, plus this type of connection is simply much more reliable. In recent years, Panasonic has been very innovative in the digital camera market. The Panasonic model described above, is the first camcorder shooting 24p in the mini-DV format . And Panasonic now has (or will soon have) 24p camcorders at all levels of digital production. Early next year, Panasonic plans to release the AJ-SDX900 24P DVCPRO Cinema(tm) Camera, a 2/3-inch, 3-CCD, 16:9, DVCPRO50 format camcorder that can acquire higher-quality images at 24-frames-per-second (expected price is US$35,000). The quality will be roughly equivalent to Digital Betacam. And Panasonic already has several High Definition models on the market. Most notably their model AJ-HDC27V multi-frame-rate HD camcorder which can also shoot at 24p. And I'm guessing all the mini-DV manufacturers will soon have similar 24p models on the market, before we know it. For those of you who want to understand what is specifically happening in a 3:2 conversion, or 3:2 pulldown process, the following diagram might help to illustrate the point. Traditionally, 3:2 pull-down is a method used to map 24fps of film onto 30fps (60 fields) of NTSC video during a process called telecine, where one film frame copies to 3 video fields, then 2, then 3, then 2, and so on. The 3:2 sequence repeats every 5 video frames and every 4 film frames. Or 4 film frames become 5 interlaced-video frames.
Here is another way of illustrating the 3:2 process. Basically, 4 film frames become 5 video frames, in a cycle that repeats itself over and over. Or in the case of the Panasonic AG-DVX100 DV Cinema(tm) Camcorder, four of the 24p-frames are processed to make five regular NTSC-video frames (or more correctly, 10 NTSC-video fields).
Copyright © Peter Gray (updated 31st July, 2002)
Peter Gray
|
