How big are the file sizes?

[Brooktop]

I am using Windows Movie Maker and currently putting together a video. When it is done, I will be converting the AVI file to DVD. My question is, how do I know when the file is the right size to fit on a 4.7Gb DVD? It's probably a dumb question so forgive me! As I go along, I'm simply saving the project - so it's not like I can simply look at the properties of that file. I'm also not sure how the conversion to DVD compatible files will affect the file size.

Any pointers greatly appreciated.

[redsox_mark]

You need to estimate the size based on:

- the length of the video and
- the bitrate used

Use a bitrate calculator such as
http://www.videohelp.com/calc.htm

Once you know how long your video is, then use the bitrate calculator to calculate the max bitrate you can use. Note if your video is under 1 hour then it will fit even at the max rate.

Or if you do the encoding in a DVD authoring app you can generally tell it to determine the rate to use to make it fit.

[senu]

...good stuff Mark

This topic was mentioned Here a little while ago

Unless you plan to do it manually, DVD authoring software will usually try and encode at best possible bitrate to fit size of disc ( ususally 4.7Gb) by default unless you force a specific setting

If you use a dual layer disc and dont plan to have a video longer than 2 hrs that would default to the " best" PQ

[redsox_mark]

Yes - the easiest way is to feed a DV-avi file to the authoring app and let it figure it out. I render to mpeg in the editor and manually calculate the rate, as it gives me more control. For example on this school musical DVD I just finished, I used a higher bit rate for the main production than I did for the "extras", as they were less important.

[Brooktop]

Thought I'd give it a run-through with what I have at the moment - an 18 minute video, the majority captured at DV-AVI quality, with a couple of lower res AVI clips from my digital camera movie mode. The windows movie maker output to DV-AVI gave a file size of 4.3GB. I then converted it using Divx to DVD (a free program) and it created a Video TS folder with 733 Mb - which by my reckoning would allow me to have roughly 2 hours worth of footage on one DVD.

[redsox_mark]

I’m not familiar with “Divx to DVD” – I assume in spite of its name it also converts DV-AVI to MPEG2 (DVD)? There is no reason to use Divx in a DV to DVD workflow. (Divx is useful if you want small file sizes for PC or playing on other devices).

At the best quality settings (bitrate), a single layer DVD can hold about 1 hour. 2 hours is often called “SP”, or “good” quality.. and it seems some software defaults to this when encoding. While 2 hours on a DVD can look OK, if your movie ends up being shorter than that, you want to increase the bitrate to increase the quality. Anything less than 1 hour should use the maximum* bitrate…. anything over 1 hour use the max bitrate that just fits… (either calculate manually or let the software calculate for you).

* The max total bitate, per the standard, is approx 9800 kbps – this is video plus audio. All DVD players should be able to cope with this. Audio takes 1536 kbps if uncompressed… if ac3 then between 192 and 384 depending on settings. 8000 kbps is often used as a maximum video rate as it will fit regardless of the audio used. Some people say that if you push the rate too close to the max, some DVD players may not cope (though they should). This can also depend on the quality of the media used… if there are more errors then a DVD player is more likely to “choke” if you push the max bit rate.

[senu]

Originally Posted by Brooktop

Thought I'd give it a run-through with what I have at the moment - an 18 minute video, the majority captured at DV-AVI quality, with a couple of lower res AVI clips from my digital camera movie mode. The windows movie maker output to DV-AVI gave a file size of 4.3GB. I then converted it using Divx to DVD (a free program) and it created a Video TS folder with 733 Mb - which by my reckoning would allow me to have roughly 2 hours worth of footage on one DVD.

Just to add to Marks post. if you do not need the extra space on the disc and can afford time, doing a higher rate encoding and ( where possible ) allowing the software do a 2-pass encoding will give you the best possible ( and error free) DVD PQ

Im also unfamiliar with Divx to Dvd and whilst it may be good , Canopus Procoder Express as featured here
is one of many I would ask you to consider trying if you dont want to let any of the DVD authoring plug-in encoders to do it for you.
It is great but costs about £45, needs internet activation and while this is no big deal it can be a p**n if changing PCs. TMPGenc 3 ( now on 4) is another affordable good encoder

[Brooktop]

Hi- guys - It does indeed do other formats and they've actually changed the name of it to ConvertXtoDVD. It can be downloaded for free here http://downloads.vnunet.com/download/32986.html#ddlSomebody on this forum recommended it.

I haven't actually burnt a DVD yet, to check the quality...but a 2 hour DVD should be fine..although the program doesn't seem to have the option to alter the bitrate. I do have a stand alone DVD-R and although a straight forward transfer (even going via analogue) gave very good results, even in SP mode, I want to go via the PC for ease of editing, transitions, titles etc.

[Brooktop]

Update: Looks like that program isn't free anymore!