ok, i'm confused..

gmes29 wrote on 8/28/2006, 5:41 AM

i start a project by bringing in a video (mpg) that is about 2 hrs in length and ~3.7G in size. i edit out all the commercials leaving me with about 1.5 hrs of video according to the timeline. i then add titles at the points where i want chapters then render the whole thing to an mpg file in prep for use in DVD architect. here's the weird part - the resulting mpg file was now larger than the original (~4.3G) even though it should be smaller now with the commercials removed. how is this possible?? i also noticed that if i change the file type to avi, the resulting file size was approx'd at only 850.xx meg which is less than a gig. now how is this possible?? last i looked, avi's of a particular video are always larger than the same video in mpg format because of the lack of compression..

Comments

IanG wrote on 8/28/2006, 7:50 AM

I'd guess VMS has encoded your mpeg at a higher bitrate than the original, though I have to admit I've no idea how the mpeg encoder handles mpeg input.

AVI is a container file format, not a video format. The video can be compressed a lot or a little depending on the codec (compressor / decompressor) used to create the file. DivX files are .AVIs and they're smaller than mpeg2. Of course that begs the question - which codec did you use? Unless you selected a DivX or XviD codec then you're right - the avi should be bigger.

Ian G.

gmes29 wrote on 8/28/2006, 8:37 AM

don't remember which 'version' i selected for the avi but i'm almost positive i chose 'DV NTSC' for the mpg which i believe is the correct option..

this brings up another question..
do i even need to render my project to a file in order to use DVD-Arc to create a full menu driven DVD??

Chienworks wrote on 8/28/2006, 7:08 PM

DV NTSC is a format for AVI, not for MPEG.

The size of an MPEG file depends on the length and the bitrate. 1.5 hours at, say, 6Mbps will result in a bigger file than 2 hours at 4Mbps.

gmes29 wrote on 8/28/2006, 8:10 PM

here's what i did for the mpg..
Format: MainConcept MPEG2
Template: DVD NTSC
Description:
Audio: 224 Kbps, 48,000 Hz, Layer 2
Video: 29.97 fps, 720x480
Use this setting to create an MPEG-2 file with an NTSC DVD-compliant video stream, and an MPEG layer 2 audio stream.

these settings create my mpg at 4.3G which when brought into DVD-Arc, is too big. what do i have to do to get this mpg down to the size it should be?? can i change the codec or at least the bitrate??

Chienworks wrote on 8/29/2006, 10:15 AM

You can't change the codec if you wish to make a DVD. It must be MPEG-2. 4.3GB shouldn't be too big. That should just nicely fit on a DVD.

If you need to fit more on a DVD you can render to DV NTSC .avi from Vegas, then let DVD Architect render to MPEG-2 with the "fit to disc" option. Sadly, there is no way for you to change the bitrate when rendering to MPEG-2 in Vegas Studio.

gmes29 wrote on 8/29/2006, 11:08 AM

actually when i bring it into DVD-Arc, there's a rectangular area at the bottom that tells you how large the project is.. this thing was red and specified a total size of 5.xG which is definitely too big.. i have no idea where that extra gig is coming from but i'm stuck if i can't find out..

Tim L wrote on 8/29/2006, 2:09 PM

i have no idea where that extra gig is coming from but i'm stuck if i can't find out..

It's probably your audio. When you render to MPEG2 for DVD from VMS, it creates an MPEG2 file with just your video, and a separate WAV file with audio. DVDAS then re-merges audio and video when creating the .vob files for the DVD.

In the current version of VMS, we can only create DVD's with PCM audio format -- essentially, uncompressed WAV format audio. This DOES take up a lot of room. I would guess that audio being 20% the size of the video would be about right.

In the next, unofficially-announced version of VMS, it appears that we'll get to use AC3 audio, which is compressed to about 1/10th the size of PCM (I think), but is still very high quality.

Also, if you have any menues on your DVD, they will add a bit to your overall size. Very little, I think, but they do take up a tiny bit of room.

Tim L

gmes29 wrote on 8/29/2006, 4:12 PM

i may be onto something although it's just a guess..
is there any significance to the fact that when i play my project starting from the very end of the video, the scrubber keeps on going way past the end into oblivion?? is it possible VMS is rendering a bunch of empty space and that's why the video is so large??

i did some calculations. my project is exactly 166726 frames long. at 30 frames per second, that's 5557.53 seconds which divides out to 92.5 minutes - the exact length of my video. does this mean anything as far as how big the mpg should be??
also, i could have sworn i saw the frame count go way beyond the 166K during the 3 hrs it took to render the mpg..

gmes29 wrote on 8/29/2006, 7:10 PM

well that's not it.. according to the % complete, vms is only going to render the 166K frames that make up the video and nothing more.. (i'm currently rendering)