MPG2 Clips using more space than they should

PeterWright wrote on 3/12/2003, 3:17 AM

I'm just building my first project in DVDA and predictably enough seem to be doing something wrong.

I'm using four MPEG 2 clips I made in V4 (PAL defaults) plus some music, totalling 3.7 Gb, yet File > Optimize DVD tells me the following:

at 9.8 Mbs I'd have 11.1 Gb
at 0.190 Mbps I'd have 5 Gb.

I have some motion menus, but these are using footage from the same clips.

The audio is currently PCM - this can't account for the difference, but I'd like to know if I can replace this with AC3 within DVDA, or whether I have to do this in Vegas.

I love this tool, and I know these are but teething problems ...

assistance appreciated

Peter

Comments

ArysChien wrote on 3/12/2003, 3:27 AM

"Motion Menu" caused me big trouble, turning a originally 1MB menu page into a 31MB monster.

You can roughly caculate the file size of the menu by its length, about 1MB per second. The 31MB menu page I created contains a 30 second motion menu.

It's also true about stills/ picture slideshow. One picture for 5 seconds takes 5MB space.

I'm not sure if this is right, but I figure that, with DVDA there are no "file sharing". If you use the same footage from the same clips twice, it's gonna take twice as much of the space. (It took me a while to understand that a DVD is not like a *.html file......) I'm not sure about other softwares.

Arys

SonySDB wrote on 3/12/2003, 8:00 AM

You can change to AC-3 in the Optimize DVD dialog (File | Optimize DVD...). Select the media asset and change the "Format" (under "Media audio settings") to "AC-3 Stereo".

PeterWright wrote on 3/12/2003, 9:34 PM

Thanks for the tips.

I've been tweaking around with several space-saving tactics:

I've -
Limited menu lengths to 31 secs looped
Disabled Animated buttons
Changed all Audio in Optimizer to AC3

And it's getting down nearer a feasible size.

Now, I notice in Optimizer that the only way to reduce the size of the MPEG2 clips using the bitrate slider is to enable Recompress video (naturally).

As they're already MPEG2s I assume this double compression would cause some degree of quality loss,

SO:

Since one often doesn't know the eventual amount of bitrate fiddling that may be needed to fit material onto a disk, it seems that it's better to import the original DV avis into DVDA and just do a single MPEG2 conversion there. Correct?

(The trouble is - for this project I've already deleted the avis to save space, so at least I'll find out how much quality loss the double compression causes ...)

This footage is not very demanding - a static speaker at a seminar - so how low do you think the bitrate can go and still produce a reasonable picture?

peter

john-beale wrote on 3/12/2003, 10:04 PM

I don't have much experience with the lower bitrates, for a talking head against a static background, 3000 kbps might be just fine, unless the original video is noisy.