Compression/CODEC Questions

kdk2002 wrote on 7/23/2002, 2:37 PM
I have a few questions regarding compression codecs and storage:

1. What are the opinions out there about re-rendering/re-compressing an MPEG or Quicktime or Windows Media file into another format? That is, you re-compress an already compressed file into another codec. Let's say you load a MPEG2 file into the Vegas timeline and want to "re-render" it as a Quicktime file without any changes. Is this recommeded? Is there loss of quality.

I don't save any of my original, unedited .AVIs, or the original DV tapes (probably a mistake) either. But once I'm done (finished editing) with the source material, I don't need it anymore.

I would like to be able to go from MPEG2 to Quicktime back to uncompressed .AVI if I want though.

My library consists of MPEG2 files which I hope to put on DVD one day. Is there an inherent problem with this method? I just don't have the hard drive storage all the original .AVI files.

Thanks!

Comments

HeeHee wrote on 7/23/2002, 2:50 PM
You are typically going to get equal to or less than the quality of the file you are converting. You can never get better quality. That is why most experts will tell you to use uncompressed or atleast DV AVI files when editing your project. Uncompressed AVI is as high quality as you can get and DV AVI isn't far behind.

If you are using Digital media like Digital8 or MiniDV, you should consider printing your final project to tape for archiving. The tapes aren't that expensive as compared to hard drive space and then you can always go back to them if you need them and still have great quality. And Yes, not saving your original tapes was a mistake. Oh well, a lesson learned!
MCTech wrote on 7/23/2002, 9:19 PM
It's generally not advisable to re-compress MPEG. Because of the highly compressed nature and the methods used, re-compressing MPEG can result in significant quality loss. The same advice applies to many other formats. If a compression method is lossy, you will lose quality every time no matter how good the encoder/codec is. That's just a limitation of lossy compression.

Whenever possible, it's best to start with the most pristine source material you have.

MainConcept Tech Support