iDVD Size Issues

[namooney]

I received a data dvd that contained a bunch of podcasts in .mp4 files. I am now trying to make a dvd that will have the different podcasts as videos in different chapters so that it can be played on a regular DVD player. The problem I am having is that when I move the podcast into the iDVD project it takes up so much space. For instance on the computer the size of the video (49 minutes long) is only 23.2 MB but when I move it to the iDVD it takes up 2.7 GB in the file. Why the discrepency? How can a file that is 23.2 MB on one but takes up 2.7 GB on the other?

Please Help.

Sincerely,
Nathan Mooney

 

[spinnerlys]

Because the podcast file uses the MPEG-4 (.h263/4) codec for compression and the DVD uses MPEG-2.
Also the resolution of the source files may differ from what iDVD puts out in the end (640x480 if NTSC - USA, Japan; or 720x576 in PAL - Europe, Oceania,...).

As you already wrote, the podcast only uses 23,3MB for 49 minutes of video, you can calculate that it only uses 8KB/s as a data rate.

A DVD is encoded with MPEG-2 and uses data rates of up to 1,225MB/s (9,8Mbit/s) and MPEG-2 is older and more inefficient if it comes to space.

 

[namooney]

So what now?

So what can I do? Will I only able to fit about 4 of these podcasts on a dvd?

 

[spinnerlys]

Yes, if you use single layer DVDs (4,37GB). You could use the lowest quality settings if iDVD is able to do that.

But why do you think only three hours of film (sometimes a bit more) can be fitted onto a video DVD (dual layer, 7,95GB), but lots and lots of podcasts?

MPEG-4 is a distribution codec for online material and no physical media, only for recording devices like video cameras and such.

 

[namooney]

I switched it to the lowest setting, but it is not enough. Still totals 26 GB. So are you saying that using the mp4 files, there is no way to get them on a single dvd? Can they be changed to another type of file?

 

[spinnerlys]

I switched it to the lowest setting, but it is not enough. Still totals 26 GB. So are you saying that using the mp4 files, there is no way to get them on a single dvd? Can they be changed to another type of file?

The .mp4 files are changed to another file, they are converted to an MPEG-2 .vob file(s), so they can be played as a video DVD.

Video DVDs need to use the MPEG-2 codec and MPEG-2 for DVDs is not cut out to create files with 8 kilobytes/s of data rate.


The only way to get them onto one DVD is a DVD player that plays .mp4 files encoded with MPEG-4 (.h263/4).