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Although I feel a bit of a traitor, since it has served me well, I am at last moving beyond the 720 x 576 format, (in case you wondered, I am talking New Zealand and PAL_B here), and I have been looking for a means of modernising my setup. Unfortunately, I amcaught more than halfway through a long-term undertaking, a documentary series covering the entire coastline of the province (of NZ), where I live, now into its sixth year and 96th DVD of source material. Being ‘far from civilisation’, and having, until recently, belonged to a club which thinks video is going to meander along forever based upon the4 x 3 aspect-ratio and the memers’ ‘steam-powered’ methods of achieving it’, I have had to do a lot of lateral thinking to secure the results I want; eg an easy pathway to having everything, (good quality standard footage included), upscaled to 1920 x 1080. Here is the outcome of some of my ‘lateral thinking’ on the subject.
Beginning with the premise that the outcome should determine the method, where possible, I have settled upon non-standard ‘custom’ format of my own, 960 x 540. Does that ring a bell? Linearly, it is exactly half the pixel-count in both directions, of 1920 x 1080, my desired outcome. Each square pixel, then, multiplies itself by four, making the easiest possible (if rather slow), going for ‘h264’ (the programme), which does the ‘grunty’ part of the upscaling. To create a 960 image, puts the camera output, (which has been compressed into 720 x 576), back to where it started out. I arrived at that figure both by calculation, and my experiences from having to adapt some still graphic images to fit seamlessly into an editor’stimeline, with the minimum of fuss, as they, of course, had not been laterally compressed as had been the video images. 960 x 540 was where they came-out correctly with the aspect-ratio intact, although many dimensions of the correct ‘x to y’ ratio will also work.
First-up the image is adjusted slightly, it has 18px lopped off top and bottom, to bring it to the exact 16:9 aspect-ratio and the correct dimensions to be an easy upscale. I have used ‘Virtualdub’ for both of these functions, eg the cropping, and the re-scaling.
The problem then arises as to when to best do the cropping and processing. I feel it makes good sense to do at least ‘chapters’ and if the features are not overly long, say sevento 20 minutes, which is what my production breaks down into in a ‘modular’ fashion, possibly doing the complete conversion process on the finished product.If need be, the video/audio streams may be separated for this, and re-multiplexed afterwards. By my reckoning it makes very good sense to do it that way and so, instead of prematurely transcoding shots tompg2 as I used to do, it pays to keep footage as DV AVI as long as possible, to keep ‘Virtualdub’ happy. Because most editing software, (at least at the level I am able to afford), goes ‘tits-up’ when confronted by DIY formats, it is best, in my experience, not to antagonise it by calling upon it to edit and render images in 960 x 540, however, as a final encoding, free of the restraints of the timeline, there should beno problem. If all else fails, it is likely TMPGEnc will be able to help with re-encoding using ‘custom’ settings. (For those of aninquiring frame-of-mind, AVS editing software from Britain, does at least accept 960x 540 for editing, but my experiments have not yet gone beyond that).
The techniques I have described are well into the advanced stages of being proven and my only worry is that ‘Virtualdub’ might ‘choke’ and fall over on really ambitious processes, withconsequent crashes. So, experiments continue.
The time taken to process, of course, will make ‘over-nighters’ almost inevitable rendering-wise, so it is best to simply go off-to-bed and leave the computer to-it.
If you wonder why I went this way about the process? I had been brought up on ‘widescreen’, from my film days and anamorphic lenses. I foolishly started my documentary series in 4 x 3 aspect-ratio to keep in uniformity with other members of the club I belonged to. That left me with some hours of footage which had to be cropped back to ‘widescreen’ dimensions using ‘GIMP’, which for all that I love it to bits, is a bit of a grisly thing to have to contemplate when it comes to dealing with some hours of footage. The method I have described, grew out of a lot of experience of having ‘widescreened’ 4 x 3 and is an adaptation of a process I have carried out many times, only ‘Virtualdub’ makes it a whole lot easier.
Ian Smith – Dunedin, New Zealand