avi or mpg2

Ivan Lietaert wrote on 8/15/2007, 9:18 PM
Keeping diskspace in mind, I have told VMS to render to the mpg2 format. The 'custom' button is grayed out, so there is no way to set higher bitrates. Then I burn a dvd with DVDA, which is pretty fast, as my videofiles come in the mpg2 format.

But now, I started thinking, if I would render my video to the avi format, and allow DVDA to render to mpg2, I would get higher bitrates (is de video is short), and therefore better image quality.

Am I right and should I render to avi (and buy an extra hd)?

Comments

Eugenia wrote on 8/15/2007, 10:11 PM
It depends. If you can open the actual .vf project on DVD Architect then you save one re-encoding. Also, if DVD Architect does not re-encode your .m2t file when it saves it as VOB, then it's good too. But if you save as .m2t and then it re-encodes to .vob, then you are better off with .avi, yeah.
Chienworks wrote on 8/16/2007, 4:23 AM
Hard drives are so cheap that this is almost a brainless decision these days. You can get a 500GB drive for about $100. Look for sales ... i recently picked up a couple of brand new 160GB drives for $35 each. Even a 160GB drive has enough space for over 11 hours of DV .avi files. Besides that, it's also nice to be able to hold on to some projects for a while rather than deleting everything before starting the next project.

If you're worried about this process at all, then it's definitely worth getting the extra space so you can do it right. It won't make a whole lot of difference with your shorter videos as Vegas is already using a pretty good bit rate by default. The real benefit will be when you start working on longer projects and want to make use of DVDA's fit to disc function.
4eyes wrote on 8/16/2007, 10:48 AM
Am I right and should I render to avi (and buy an extra hd)? If your source video is dv.avi captured from a dv cam then you should export your video to a new dv.avi file. Then use this dv.avi file in DVDA. In DVDA you can then assign higher bit rates.
But, if your source video is in mpeg2 format (such as from a sony handycam mini-dvd or harddisk that records directly to mpeg2 format), you cannot make the video better than the original. So, if your original source videos (on a dvd handycam) are encoded as mpeg2@ 6500kbs w/dolby audio then going higher then 6500kbs is no gain.
Actually if you go from mpeg2 to dv.avi and back to mpeg2 again you will have some loss of quality due to a few conversions, no quality gain.

So to answer your question it depends on whether your source videos are dv or mpeg video.
Start with dv and work down to the other formats with the least amount of conversions will give the highest quality.
When working with dv.avi you can render the project to a new file without hardly any loss. Nice thing about doing this (rendering the complete project to a new dv.avi file) is you can write the project back to the dv camcorder for archiving the finished/edited video. Then let DVDA create the mpeg2 video on the dvd.

I have used VMS to render mpeg2 video to dv.avi format for heavy editing, then re-convert back to mpeg2 again. VMS does a pretty nice job of converting to dv.avi. My source mpeg2 files I convert to dv.avi are encoded at 9500kbs, so the final mpeg2 files are encoded about 6500kbs (less). Notice I'm going down and not up with the bit-rates because I started with an mpeg2 video file (not a dv.avi file).
Chienworks wrote on 8/16/2007, 11:33 AM
"So, if your original source videos (on a dvd handycam) are encoded as mpeg2@ 6500kbs w/dolby audio then going higher then 6500kbs is no gain."

That's not quite true.

Every time a video is recompressed quality is lost. In your example, quality is lost when the camera compressed to 6500Kbps and then quality is lost when the project is rendered to 6500Kbps. However, even though you'll never get better quality than the original, rendering to 8500Kbps would be less loss of quality than rendering to 6500Kbps. So there is a valid reason to use a higher bitrate on the finished render than existed on the source material.