-
Generational Loss
Can someone explain when generational loss occurs?
Would we have any generational loss in any of these scenarios?:
1. We render out a veg file multiple times in multiple formats such as DVD, Bluray, Vimeo, Youtube… Did the underlying source video files incur any loss?
2. We want to test some effects and settings and render out one particular event ten times at different render settings. Did an mov file being pointed to have any loss?
3. We make ten copies of a DVD project in DVD Architect. Is the first DVD the same quality as the tenth one?
4. We copy and paste an mov that came straight from a DSLR camera and also an avi file captured directly from a tape camera ten times to different hard drives. I’m almost positive this is a bit to bit transfer and there would be no generational loss, but want to be certain.
5. We copy and paste an mp4 file ten different times.
I hear about generational loss, but obviously don’t understand when it’s an issue.
Thanks
-
3 Replies
-
[Mark Davidson] “Can someone explain when generational loss occurs? “
When you render from a codec that is lossy to any format, or to a codec that is lossy from any format.
[Mark Davidson] “1. We render out a veg file multiple times in multiple formats such as DVD, Bluray, Vimeo, Youtube… Did the underlying source video files incur any loss?”
No, the “source” videos themselves never incurr any loss but the rendered video did. DVD, Blu-ray, and Vimeo (AVC/H.264) are all lossy formats so there will be some generation loss in the rendered video.
[Mark Davidson] “2. We want to test some effects and settings and render out one particular event ten times at different render settings. Did an mov file being pointed to have any loss? “
What does “being pointed to” mean? You need to ask your questions in terms of “source video” and “target video”. The source will never be changed. The target will.
[Mark Davidson] “3. We make ten copies of a DVD project in DVD Architect. Is the first DVD the same quality as the tenth one?”
How did you make the copy? If you created 10 copies from within DVD Architect all of the DVD’s are the same quality. If you physically digitally copied the DVD with your computer the copies will all be the same quality. If you somehow played the video back into your computer and captured the output there will be a loss in quality.
[Mark Davidson] “4. We copy and paste an mov that came straight from a DSLR camera and also an avi file captured directly from a tape camera ten times to different hard drives. I’m almost positive this is a bit to bit transfer and there would be no generational loss, but want to be certain.”
That’s correct. Copying files incurs no loss in quality.
[Mark Davidson] “5. We copy and paste an mp4 file ten different times. “
No loss.
[Mark Davidson] “I hear about generational loss, but obviously don’t understand when it’s an issue.”
Generation loss occurs when you convert the video into another format. Either from one codec to another, or from digital to analog or analog to digital.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
OK great, that makes sense, thank you.
I got hung up on the meaning of the word “generational”.
-
Yea, copying a file is a digital transfer so no generation loss.
It is possible to compress a video and have no loss. These are called loss-less codecs like Huffyuv and Lagarith. You can render them again and again with no loss. Kind of like ZIPing up a file to make it smaller but there is no loss when you unzip it. It’s only “lossy” codec compression or analog transfer that incurs a loss.
~jr
http://www.johnrofrano.com
http://www.vasst.com
Reply to this Discussion! Login or Sign Up