Hi all,
I recently got the 20th anniversary box set (dvd-video), and after running dvd2daph and daphne, I've been having a lot of fun with these LD games of yore, so thanks to the creators and contributors for all the work.

I've been looking at the dvd2daph (3.0) script for fun and to see if I could make any improvements, but I've got a few questions if anyone can help. (Not sure whether to break these up into separate posts...)

1. 24 fps vs 30 fps: VirtualDubMod (and other tools) tells me that the m2v files for DL & SA created by dvd2daph are all 30 fps, as are the original vob files. While dvd2daph does do a "Telecide" on DL to get rid of (most) interlaced frames, it does not do a "Decimate" to reduce the fps. The SA mpegs are untouched. While I think this conclusion is correct, Daphne always tells me:
"NOTE: converting FPS from 23.976000 to 29.970000. This may be less accurate."
I know daphne needs to run at its native 30 fps, but it seems the mpegs are already there. Is this a false warning, or am I missing something obvious? It plays fine, btw.

In some other cases:
I decimated(cycle=5) DL to get 24 fps m2v's and got no conversion warning. Why not? Doesn't daphne's builtin mpeg decoder (libmpeg2 I think) have to convert to 30 fps (ie on-the-fly telecine)?

I ran the Cliff2K3 teaser (from the dvd2daph site), which is apparently a 24 fps clip, on daphne and got
"NOTE: converting FPS from 29.970000 to 23.976000. This may be less accurate." That's just weird.

2. SA and DL2 ivtc: I've been working on improving the avs scripts for DL; while the DL vobs seem to be "hard-telecined" and full of interlaced frames, I noticed the SA and DL2 footage do not have any (clean). Stepping through the frames with VirtualDubMod, it's as if they've already been telecided (all interlaced frames reformed as progressive), but not decimated as they're still at 30 fps. You can see every 5th frame is a copy of the 4th. Vera mentioned perhaps future ivtc scripts for SA and DL2, but isn't this unnecessary? I guess you could decimate these extra 5th frames and the "judder" (jerkiness) they produce when watched in a plain media player, but daphne (I presume) just puts the judder back in when it telecines it to 30 fps, so why bother? Vera also mentions 24 fps being ideal, but isn't the original 30 fps, but with all the interlaced frames cleaned up, better since no conversion to 30fps by daphne is needed? And for SA and DL2, no re-encode either. I hope I'm not missing something stupid here:^)


Not to be presumptuous, if anyone wants me to elaborate on "Telecide" and "Decimate", I can.

Thanks in advance for any help.

dvd2daph 4.0 no longer uses avisynth and avoids re-encodes on any kind. It's unnecessary since Matt_O added the -blend feature to daphne.

The fps conversion messages are normal. They basically just say that because a conversion is happening, daphne could (at most) be one frame off.

Daphne does not need to run at 30 fps; it can run at any framerate and is only restricted by the hard-coded framerates in mpeg files. Also your monitor's refresh rate will be a factor for what you actually see.

The warning message means that the laserdisc frames are relative to a 23.976 framerate (and hence the seeks that the ROM sends to the laserdisc player) but the mpeg is relative to 29.97 framerate, hence Daphne must do a mathematical conversion to make sure you see the frame the ROM wants you to see, and therefore the seek is approximate and not exact.



The situation is now reversed. The laserdisc frames (and ROMs) are relative to a 29.97 framerate, but the mpeg runs at 23.976 framerate. So once again, a frame number conversion must be made. It's not an error, just a 'heads up' that the seek is approximate and not exact.

Thanks Matt, chip, for the quick answers. The fps explanation was precisely understandable; I guess I completely mistook some earlier posts I found, that 30 fps was standard. So 24 fps is ideal for DL and SA (if only to avoid the off-by-one), while it is different (30 fps) for CH. So, as I understand it, daphne plays the mpegs as-is, ie it does not speed up or slow down the actual source frame rate (say by telecining), but it converts it's internal frame calculations to compensate for frame rates different from the original.

dvddaph 4.0 is coming?? That's great, can't wait. I did remember seeing some -blend posts, but I guess I didn't realize what it was; let's see...On-the-fly deinterlacing, using the "blend" method I presume? (as opposed to bob,weave,etc) - forgive how I sound, I'm just reading/googling this stuff as I write this. Great feature, I'll have to try this on some interlaced footage.

I guess that means the ivtc scripts I'm working on are a waste of time. But on-the-fly "blend" isn't the same as a true inverse telecine, right? I think that makes me feel better (I'm just fixing some problems with the old avs scripts (dvd2daph3.0), which missed a lot of interlaced frames in the standard DL footage and did not work at all on the prototype footage; it's really only noticeable if you play it in slo-mo or frame-by-frame, but I'm a perfectionist.)

you got it!



It's here. See the post in the video editing/capture forum.



yes, ideally you would ivtl the streams for the best image quality. But, if you want the best image quality, you're better off learning the intricacies of capturing laserdiscs than playing with ivtl scripts. But, I'm sure there are people whowould appreciate your scripts once you're done with them.

dvd2daph used to ivtl and re-encode certain streams because it *had to* due to a bug with certain stream formats. But, that's now been fixed, so re-encoding isn't necessary. Thus, the ivtl scripts have been removed. The goal of dvd2daph is to give you the streams directly from the dvds with no visual changes, just that they've been converted to daphne format. Any sort of ivtl/re-encoding/changing of the video is a subjective art form and what is "best" is the opinion of the user. Therefore that part of the process is left up to the user. However, the files are perfectly fine as-is post-conversion for most users, especially since -blend was added. Hey, they were good enough for digital leisure to put on the dvds that way.

There's actually still one issue with dvd2daph 4.0 that we're trying to sort out. Seems like you know a lot about this stuff too. You're welcome in the chatroom, maybe you can help us.

Thanks chip, that's encouraging - I'll finish them up and post on one of the forums in case anyone is interested.



Ahh, that's an interesting tidbit, I was wondering about just that thing (the necessity of a re-encode). You're right about post-processing being a very subjective thing, and there are so many different things you can do (noise filters, etc). In fact, I was stripping out everything except the ivtc as I felt preserving the source as much as possible (other than ivtc, imho) is probably the one thing everyone can agree on.

One very simple thing the avs scripts did that was nice was crop off the bottom of the prototype footage, the last 6 lines or so, which were just garbage (like vhs tracking distortion or sth). Digital Leisure didn't bother I guess because the overscan on a TV would hide it, but on a computer monitor it is just yuck.

Just read the dvd2daph beta post. I'd love to help, sounds like fun. I'll drop by and see what's going on.

24 fps is ideal for almost all of the cartoon-based laserdisc games. But only Dragon's Lair and Space Ace are convenient to convert to 24 fps.



Blend is just a cheap trick that blends the even and odd fields together so that the 3:2 pulldown 'effect' is not as noticeable. But you will still see "ghosting". So IVT is still preferred.

yeah, I'm interested to see them. I know there are many people here who will use them.



some would argue the other way on the ivtl topic. For instance, if you're playing back daphne on a television, the 30fps telecined stream (without IVTL) is ideal. On my daphne cabinet, which has a television installed, I keep my laserdisc captures telecined.

So, just to state it again, the goal of dvd2daph is to give you unaltered files directly ripped from the dvd, the one exception being that they're converted to daphne format. What you do to them after that is completely up to you.