I have been lucky to find and downloaded some TV series which will never be available in my country. Same thing for some old movies. All of them are avi types, around 700MB in size, which were compressed using Divx. Until now, when I found files like this I upgraded them to full DVD MPEG2 quality. But I think I am wasting bandwidth and DVD space by doing so. Recently I could see how you could work on the bitrate, when converting from avi to MPEG2, and make files smaller. I think a similar procedure could be applied on this Divx files. Is there a "scientific" way to compute how high this bitrate should be so as not to waste it with quality that is not there, if you know what I mean? Perhaps I could fit several episodes or two movies and still have the original compressed quality. How do you do that? Trial and error?
Start with resolution. If the original is 352x240, there's (almost) no point in upsizing it to 720x480/576 and putting it on DVD. If you leave the size as is, you can encode to 1/4 D1 mpeg-2, that is DVD compliant, and save at least half the bitrate. This allows for at least double the video running time per disk.
OK. Let's see if I get it. Using Gspot I could find, on a film I have that is anamorphic, Xvid encoded, that it's 640x272 (2.35:1) [=40:17]. The bitrate seems to be 1492 kbps. Should I load that data on the Procoder MPEG2 DVD NTSC output setup? It's the only place where I can change anything. Isn't that bitrate too low?
XviD bitrate has nothing to do with mpeg-2 bitrate. The two codecs compress completely differently. An XviD of 640x272 would best be encoded to full D1 (720x480) letterboxed, because it's a high res avi. An Xvid of 352x140 would probably best be encoded to half D1 letterboxed, because there's no point in increasing it's aspect, you're simply adding noise/reducing quality by doing so. Because your example XviD is high res (and should be reasonable quality), it would probably be safe to encoding using an mpeg-2 bitrate that will run about 2/3 of a DVD, or about 3 gig. Going larger may be a waste. Going smaller will lose quality. How did I come up with 2/3 you ask? It's resolution (640x272) is approximately 2/3 of a full D1 mpeg. That's just a rough guess, because I haven't seen it, and have no idea of it's running time, or basic quality. If it's running time is less than 2 hours, then my reasoning is sound. If it's closer to 2 1/2 hours, then encode it to fill the disk completely. If it's only an hour, you're wasting space and bitrate by going larger.
Ok. I think I am beginning to get it. But the only variables I can change on Procoder besides bitrate, are those involving aspect ratio configuration: video aspect ratio and pixel aspect ratio. How can I set those 2/3 in there? My first guess is I might set the bitrate at 4000 kbps (2/3 of 6000) and perhaps use that 40:17 ratio for setting the video aspect. Please remember I will transcode this PAL film onto NTSC. On a recent anamorphic project I transcoded, I was advised to set 16:15 at the pixel aspect ratio. As you quite well put it, it's a question of using neither more or less than what the original needs.
[bold] ...Encoding using an mpeg-2 bitrate that will run about 2/3 of a DVD, or about 3 gig...[/bold] These words of yours really set the whole thing. My question is how I can set that for maximum quality on this specific anamorphic film. But the question on how to correctly set a 4:3 film, which is how most TV episodes are formatted with, when that file is compressed in Dixv or Xvid, is also important. Quality is also lost on that compression. Let's use an example: one episode of this series is analyzed by Gspot as being 576x416 (1.38:1) [=18:13]. That is a ratio of around 4:2.9. Runtime is 1 hour 39 minutes, which of course would fit on one DVD disc. But I would like to put two episodes on one disc at least. Which might not be feasible, perhaps. There must be rule to follow here that I can't quite grasp yet.
No, there is no rule. If it's a high quality source, of large aspect (at D1 or close to it), then 2 hours per disk is max. Use the bitrate calculator to figure out exactly what mpeg-2 bitrate you need to encode it at. If you're viewing it on a 4:3 TV, then you encode it letterboxed, so the sides don't get cut off. Just saying a video is DivX or XviD doesn't mean anything. There are some extremely good qualtiy, and some extremely BAD quality videos using both compression codecs. No matter what the aspect ratio/size is. What I'm trying to convey, is if your source is high quality, and large aspect, then keep the quality by putting no more than 2 hours per disk. If the source is not so good quality, and a smaller aspect, you can encode it to a smaller aspect, using less bitrate, fit more on a disk, and not LOSE any quality by doing so. 576x416 is Anamorphic. It's large enough to be encoded to a full D1 (720x480) mpeg-2. It's running time is 1:39, which is only 1/6th short of 2 hours, so you may as well use a bitrate to fill a DVD disk. This would be 5931 kbps video, with 224 kbps audio. It may be a bit of overkill, but better to use slightly MORE bitrate, and maintain quality, than reduce it and suffer. You COULD encode it to fit half a DVD, so as to get two episodes per disk, but I would reduce it's aspect during encoding as well, so the lower bitrate can be fully used to maintain the quality... That is, encode it to 480x480 instead of 720x480, then use a bitrate of 2851kbps, but this reaches into the realm of SVCD, and is probably too low a bitrate for 480x480...so we go to the next option, which is 1/4 D1. This is 352x240 aspect, so you need even LESS bitrate to maintain original quality, and the 2851kbps is good. Beware that watching this on a standalone will depend on your TV size. On a 26" std TV, it may look great. Playing it back on a 42" Plasma, and it will look absolutely horrible, because it's being resized UP so much. Disks are cheap. Encode one episode each, to Full D1 to fill a blank, and your eyes will thank you
[bold] Use the bitrate calculator to figure out exactly what mpeg-2 bitrate you need to encode it at. [/bold] Having a bitrate calculator would be great! Can you tell me where to get one? My present and future TV size are certainly an issue. A 42" plasma screen or an even larger projection screen are plans for my future, near or not so near. So I am certainly worried about image quality. What I don't want to is waste bandwidth where I don't need to. This the main reason why I raised this bitrate question. Until now I had left DVDShrink to take care of that, and I could get away with up to 5200GB size when burning that with Clone2DVD. But I better take care of this matter a bit more accurately.
http://www.videohelp.com/calc There's your bitrate calculator for DivX and mpeg-2. If you're going to buy a new, large TV in the near future, then definitely only put one episode per disk. You're not really wasting anything, but you will (at minimum) maintain whatever quality is in that video, you won't be decreasing it. If you try and squeeze two episodes onto one disk, you risk losing whatever quality is there, or at least reducing it enough, that it may look OK now, but look like junk on a big TV. It's too bad, whoever put that crap on the web, had to have it in such a screwed up aspect ratio... Why don't you buy yourself a good capture card, and record your own stuff?
[bold] Why don't you buy yourself a good capture card, and record your own stuff?[/bold] Who says I do not? Of course I do that. I have a Canopus ADVC100 and I record stuff directly from the DirecTV sat receiver, using the S-Video output. Got great stuff using it, some that never got to DVD yet. Only two problems though: HBO/Cinemax, who screens most films on DirecTV with some quality, very rarely respects the original format, be it 16:9 or anamorphic. Which is one thing I still can get o stuff I get from the web. And I have to get by the channel logo, which is something I would like to do without. After all I am paying extra for those channels, so I think the image should devoid of any logos or ads, but as you can see that is very difficult. Sometimes I think that our consumer rights are not taken care of by no one. It's quite likely than when TV gets completely digital they will find a way to block us from taping for our own use, once again limiting what I think are our rights. Of course they will disagree. Some older TV series are even a greater problem, particularly Star Trek stuff or the Cracker series, which may never get released here. So I have to be happy with what I can get through the web. Divx compressed films proved reasonable quality at least, better than I expected. But some MP4 compressed films are not. DVD-R discs are quite cheap nowadays, so I certainly prefer to upgrade to it, but on some cases it might be more effective or unnecessary to do it.
ROFL. Don't be offended. I had no idea you knew the first thing about capture, and if you DO use the ADVC frequenly, and encode for DVD, then you should understand bitrate. I also hate having logos on channels that I pay extra for. Unfortunately, there's no easy way around it. As for getting those episodes of hard to find series, I feel your pain. Luckily, where I am, reruns are plentiful. It's new content that takes 3 years to broadcast.
Oh, no. I am not offended. There'sno way for you to foresee what people really know. It's a question of the choices I make not to learn much about anything until I am going to need it. On the other side I worked professionally in film & analog video, but always with that above policy, particularly for video, both as a producer and director. Only very recently did I work with DV on some of my projects, and also learnt (and suffered) some of that medium terrible limitations and weaknesses. Now that I am getting back to production projects I need to learn a lot on how really things tick, as I was in awe on how little people really know on how to do things well. But those are matters for other forums...
