Questions about DVD creation

[downhilljon]

Hi there,

I am in the process of creating a DVD from footage obtained from a helmet cam, and getting very confused!

I have created a couple of basic DVD's previously from my own captured footage, so I have a reasonable understanding of the basics, but now am trying to get a little more professional and paying attention to aspect ratios, etc.

Here are the problems I am having:
1. Aspect ratio - the source footage I have is 720x480 PAL. I would like it to be 720x576 PAL. I have played with FitCD to generate AviSynth scripts, and am not fully understanding the output. Here is what it generates:

 
# -= AviSynth v2.5.8.5 script by FitCD v1.2.8 =-
AVISource("C:\Documents and Settings\Jon\Desktop\Test\File.avi")
BicubicResize(688,512,0,0.6,8,1,704,478)
AddBorders(16,32,16,32)
#Trim(0,781).FadeOut(150)

Is there any reason I can't just simply use this?:

AVISource("C:\Documents and Settings\Jon\Desktop\Test\File.avi")
AddBorders(0,48,0,48)

I don't see the need for cropping then resizing the video before adding borders to reach the desired size - to me that is the equivalent of discarding some of and then distorting the captured image!

Alternatively, is there a good way of handling this resizing in Premiere?


2. Editing/authoring programs and file compatibility
With my previous attempt at a DVD, I used Cyberlink PowerDirector for editing, then Adobe Encore CS4 for authoring. It turned quite ugly. The audio in the .mpg files that PowerDirector output wouldn't import into Encore, meaning I had to:
- demux audio
- convert to .ac3
- deal with the fact that the conversion to .ac3 minutely change the length of the audio clips, putting it out of sync
- import the new audio stream to encore.

It all worked out, but was a major pain in the ass!

I am now experimenting with Adobe Premiere to try and simplify the process. I'm not sure whether the best approach is to split the audio and video from the start, and if so at what stage do I re-mux them?

Can anyone suggest a streamlined approach to the following project?
Source clips: 720x480 PAL Xvid compression with audio I will use
Audio tracks: mixture of .mp3, .wav and .wmv
Desired output: 720x576 PAL DVD compliant MPEG-2, ready to author without further demuxing and audio conversion.

I would prefer to use Premiere to edit, and Encore to author.

Am I asking too much????

Thanks for any help given, please let me know if you require any further info.

[manono]

1. Aspect ratio - the source footage I have is 720x480 PAL.

I'd have to see some evidence to accept that. What's the source of that information? PAL is 25fps, you know, and 720x480 is rarely, if ever, paired with 25fps.

I would like it to be 720x576 PAL. I have played with FitCD to generate AviSynth scripts, and am not fully understanding the output. Here is what it generates:
Code:# -= AviSynth v2.5.8.5 script by FitCD v1.2.8 =-
AVISource("C:\Documents and Settings\Jon\Desktop\Test\File.avi")
BicubicResize(688,512,0,0.6,8,1,704,478)
AddBorders(16,32,16,32)
#Trim(0,781).FadeOut(150)

Why do you want all that black around it? You could always turn off the default 2 blocks overscan and do a straight resize to 720x576:

LanczosResize(Width,576)

Is there any reason I can't just simply use this?:
Code:AVISource("C:\Documents and Settings\Jon\Desktop\Test\File.avi")
AddBorders(0,48,0,48)

No, as long as you don't mind completely wrecking the aspect ratio.

[downhilljon]

Hi manono, thanks for the quick reply.

I'd have to see some evidence to accept that. What's the source of that information? PAL is 25fps, you know, and 720x480 is rarely, if ever, paired with 25fps.

OK, I have uploaded a screenshot from GSpot showing the resolution and fps.

Why do you want all that black around it?

I don't really want black all around it - I was simply following what FitCD generated. Haven't been using it very long, so I guess rubbish in = rubbish out. I'll try your suggestion.

However, that leads me to my next question. As my original captured resolution is 720x480, doesn't resizing it to 576 stretch it? Thats why I was trying to simply 'pad out' with the 48 horizontal lines top and bottom to reach the required resolution of 576. So having said that, is there an easy explanation for the following statement, to help me understand where I am going wrong?

No, as long as you don't mind completely wrecking the aspect ratio.

Thanks,
Jon

[manono]

For some reason FitCD's default behavior is to add 2 blocks overscan, which you shouldn't want or need. Just resize it as I suggested.

As for why a straight resize to 720x576 is preferable to maintain the aspect ratio, you have to remember that neither 720x480 (1.5:1) nor 720x576 (1.25:1) is the desired output ratio (1.33:1, I assume). MPEG-2/DVD video gets resized at playback time to the proper aspect ratio. I'm assuming it's going to be reencoded as 4:3.

And yes, I guess it really is 720x576@25fps. You said it's from a helmet cam. A helmet cam created an XviD AVI at 720x480@25fps, along with MP2 audio? Or was something else done to it between the filming and now?

[Gavino]

A helmet cam created an XviD AVI at 720x480@25fps, along with MP2 audio? Or was something else done to it between the filming and now?

Something's obviously been done, as I don't think many cameras have VirtualDubMod built into their firmware (see metadata in GSpot report).

GSpot also reports PAR as 1.0 ('square pixels'), although that's not necessarily definitive.
Does the video look right when played in a media player or is it horizontally squeezed?

[DB83]

Surely the question is what the format of the video originally shot with the cam ?. The OP is in Australia so it is perfectly feasable to use the assumedly NTSC ratio at 720*540 but then has some attempt to change the frame rate gone on ?. Leave that as well at 29.97 ? And messing with creating xVIDs from whatever footage you have will not create DVDs of a very good quality.

[downhilljon]

Hi guys,

Thanks for the replies.

I can assure you that the format of the video as shown in GSpot is as it comes out of the helmet cam. I think the reason that the metadata from GSpot references VirtualDubMod is that I did trim the clip to length using VirtualDubMod, but it was a direct stream copy.

Does the video look right when played in a media player or is it horizontally squeezed?

The video looks fine when played in a variety of media players, not squahsed or stretched.

MPEG-2/DVD video gets resized at playback time to the proper aspect ratio.

OK, so this is the link I was missing, and will have to research further - I just assumed that if PAL DVD specs were 720x576, then that is what the output video had to be.

Thanks again for all the info.

Still hoping someone can suggest a nice streamlined method of editing and authoring this footage onto DVD!

Cheers,
Jon

[manono]

I don't know what editing you want to do, but encode it in HCEnc or some other MPEG-2 encoder and author with the MP2 audio (which will have to be converted to 48kHz) using Muxman. You already have the script.

Or use some all-in-one program such as Avs2DVD or DVD Flick.

[DB83]

Now I also inadvertingly mis-informed you. I should have quoted NTSC as 720*480 and not 540.

Now if the native format was xVID I would have expected to see 720*544 for correct aspect ratio. But you cannot make a PAL DVD out of what you have. There will not be much variance but your images will be slightly taller than they are when you resize your video to 720*576. No DVD program will accept 720*480 to make a PAL DVD. So I still wonder whether, un-wittingly, Vdubmod re-encoded the frame rate to 25fps when you did that trimming.

How did you get that footage from the camera on to your PC? That may be the clue to the 25fps. 720*480 @ 25fps is all too odd to be native.

[downhilljon]

DB83:

How did you get that footage from the camera on to your PC?

It just records onto an SD card, then I copy the files directly to PC. It is definitely recorded in 25fps, because that is what it is set to in the camera settings. I can choose PAL or NTSC, and different quality levels, but the highest quality resolution is 720x480.

I chose PAL in the camera settings because that is the system here in Oz. I guess the next question is how easy is it to convert from NTSC to PAL in terms of frame rates and resolutions? If I set the camera to record in NTSC 720x480 from now on, will that make things much easier in terms of getting to my desired output, which is a PAL DVD?

At the end of the day, I'm just looking for the simplest process from A (source video from helmet cam) to B (PAL DVD with minimum cropping or distorting necessary).

manono:
OK, so just trying to get this straight in my head:
- Split audio and video
- Put video into editing program
- Encode to MPEG-2 using the resizing script
- Author, combining video and audio.

Quick question though:

and author with the MP2 audio

I thought DVD compliant files were required to have at least one channel of AC3 in there? Is that true? Should I convert the audio to AC3 instead?

[manono]

manono:
OK, so just trying to get this straight in my head:
- Split audio and video
- Put video into editing program
- Encode to MPEG-2 using the resizing script
- Author, combining video and audio.

That's right. Again, though, I'm not sure just what kind of editing you have planned. If you're cutting stuff out, of course you'll want the audio still attached to the video so it gets cut at the same time.

I thought DVD compliant files were required to have at least one channel of AC3 in there? Is that true? Should I convert the audio to AC3 instead?

MP2 (MPA) audio is compliant for PAL DVDs. It's not required to have AC3 along with it. The main thing you'll have to do is make it 48kHz from its present 32kHz. You can keep it mono or make it dual channel mono. You can keep it MP2 or reencode it for AC3, up to you.

[Gavino]

If I set the camera to record in NTSC 720x480 from now on, will that make things much easier in terms of getting to my desired output, which is a PAL DVD?

If your final target is a PAL DVD, you want to shoot at 25fps, otherwise a framerate change will be necessary to create your DVD. I assume the NTSC setting will use 30 (or 29.97) fps, so set the camera to PAL.

[DB83]

You may, or may not, be a little confused by all the data being thrown at you. Let me try to put this somewhat clearer.

1. PAL DVD = 720*576 @ 25 fps
2. NTSC DVD = 720*480 @ 29.97(30) fps

At present you have a bit of one and a bit of the other. You either:

a. resize you video to 720*576 - relatively easy (just watch the interlacing)
b. change the frame rate to 30fps - can be done but video may not be as smooth as it is now.

One thing which may have escaped you. Since you are in OZ there is absolutely no problem in making a NTSC DVD and it is virtually guaranteed to play on your equipment without any modification - just ensure your player, and most do, says 'NTSC playback'

But as your native format is xVID, you have yet another option and again this will depend on your player. Most current players will play this format so you just burn the video to a disk as a 'data disk' rather than as a 'dvd-video' disk.

There is one other option which may appeal to you but you may need some special tools for it. You place your 720*480 video into a 720*576 frame. This creates a little 'letter-box' effect. But it retains your present aspect ratio AND your present frame-rate AND you can then make a standard PAL DVD.

[manono]

You place your 720*480 video into a 720*576 frame. This creates a little 'letter-box' effect. But it retains your present aspect ratio...

No it doesn't.

[DB83]

You place your 720*480 video into a 720*576 frame. This creates a little 'letter-box' effect. But it retains your present aspect ratio...

No it doesn't.

Have you tried it ? I have. And this is what I had - original frame is 720*480. New frame is 720* 576 and 48 pixels top and bottom:

[manono]

Have you tried it ?

Why would I try something so obviously wrong? You're showing the 720x576 raw picture, before it's been resized to its correct (now incorrect, because of that letterboxing you did) aspect ratio. I already gave the instructions on how to prepare it for PAL, resize to 720x576, no letterboxing. In that picture you're showing, that guy is too fat and wide and is itself at the wrong aspect ratio. When being resized as a 4:3 PAL DVD Video, he'll become even fatter and wider with an even greater aspect error.

You did make one valid point though, and that's having to do with interlacing. Because it's an XviD I was assuming it's progressive. If it's interlaced it isn't as easy as doing a straight resize to 720x576. It'll have to be done in an interlace-aware manner.

[DB83]

Except I have done no letter-boxing. The original frame WAS 720*480. Now if the guy is too fat because of that then it is not my doing. I am simply illustrating a method of placing a 720*480 image into a 720*576 without stretching the image vertically. Then the guy could be too thin. You pays yer money and you takes your choice.

[manono]

Except I have done no letter-boxing.

Eh? Then what's that picture above?

The original frame WAS 720*480.

Right, a 1.5:1 ratio. To convert it to PAL you do a straight resize to 720x576, a 1.25:1 ratio, neither the NTSC nor the PAL resolution having the 'normal' playback aspect ratio. At playback time it gets resized to some 1.33:1 ratio, one such as 640x480. I already explained this earlier, if you had bothered to read it.

I am simply illustrating a method of placing a 720*480 image into a 720*576 without stretching the image vertically.

You're illustrating nothing except your own ignorance. It has to be stretched vertically when being converted to PAL resolution.

You pays yer money and you takes your choice.

That's right, and the choices are the right way and everything else. I was going to illustrate what happens using your own picture, but it's not good enough. If you had a picture with something round (sun, moon, ball, clock, etc.) it would be better. If you understand FitCD (too much to expect, I think), then here's a pic showing how it's done:

[Gavino]

To convert it to PAL you do a straight resize to 720x576, a 1.25:1 ratio, neither the NTSC nor the PAL resolution having the 'normal' playback aspect ratio. At playback time it gets resized to some 1.33:1 ratio, one such as 640x480.

That's true if you assume the correct DAR of the source is 4:3. But perhaps it really is 3:2 - GSpot reports it as such and the OP says in #7 that it looks OK when played in a media player.

If so, it should be resized to 720x512 and letterboxed out to 720x576.

[DB83]

Ok. My last word. What I was trying to do was illustrate a method whereby one could maintain the aspect ratio of the original video but enhance it so that any distortion due to resizing, whether it be at the editor stage or the playback stage would be minimal. The method may not be universally acceptable but if the original video has no distortion it could work as the PAR of the enhanced video is now correct for the intended dstination ie PAL DVD.

Unfortunatley, the video I chose to make the illustration is distorted and ultimate playback could even distort it all the more.

I have done another frame just to show what could happen when you resize from 720*480 to 720*576. I will accept that this image looks more natural.

[Gavino]

What I was trying to do was illustrate a method whereby one could maintain the aspect ratio of the original video but enhance it so that any distortion due to resizing, whether it be at the editor stage or the playback stage would be minimal. The method may not be universally acceptable but if the original video has no distortion it could work as the PAR of the enhanced video is now correct for the intended dstination ie PAL DVD.

As I understand it, your method consisted of converting a height of 480 to 576 by adding 48 pixels border top and bottom. This does not change the PAR at all, so how can it be correct?

If the original video has no distortion (DAR=3:2, PAR=1:1), then my solution (resize to 512 and add borders) is required. OTOH if the original video has a 4:3 DAR, then manono's solution is appropriate.

[manono]

That's true if you assume the correct DAR of the source is 4:3. But perhaps it really is 3:2 - GSpot reports it as such and the OP says in #7 that it looks OK when played in a media player.

You yourself said the GSpot report wasn't definitive. I'd say it's useless. Admittedly there are some peculiar things about this video, but with the small amount of information we have to go on I'd still say it's supposed to be 4:3. I did qualify some of my earlier statements saying I was assuming the playback ratio was 1.33:1 and that the DAR was 4:3. The fact that the OP says things look 'normal' I'd take with a grain of salt as without something round to go by, the slight flattening of people and objects in a 4:3 but unresized 720x480 video could easily be overlooked. If there's something round in it, I wouldn't mind seeing a piece of this video. While I have seen 25fps and 720x480 MPEG-2 videos before (PAL2NTSC conversions), I have yet to see a video that's purposely meant to be displayed at 1.5:1

[Gavino]

Admittedly there are some peculiar things about this video, but with the small amount of information we have to go on I'd still say it's supposed to be 4:3.

Yes, I agree your intuition is probably right. All I was saying is that we don't know for sure, and giving a solution for the case that the video really is 3:2.

downhilljon - Any references for this helmet cam?