AVI save reduction in quality

hbwerner wrote on 12/7/2003, 6:43 AM

I notice on my Screenblast MovieStudio that I can save a production to file as AVI, whcih I always considered uncompressed, but there is another AVI option which makes a file twice as large. Any insight into this? I have noticed some deterioration and blocking after several cycles of save, transfer to DV tape and back to computer for more editing.

Comments

Former user wrote on 12/7/2003, 7:58 AM

AVI is a file format. It is not related to Compression. You can save a file using many different codecs which result in different compressions. The DV codec is ~5:1 compression. MJPEGis ~10:1. You can also save uncompressed.

DV codec can lose some quality if it is uncompressed/recompressed a few times. The transfer from pc to camera and vice versa should be lossless, but adding effects and transitions causes it to re-render which is where the quality will change. Usually it is not noticeable.

What format are you starting with?

Dave T2

hbwerner wrote on 12/7/2003, 10:23 AM

Dave,
Thanks for the clarification. I had previously thought of AVI as a lossless type of file.
I'm starting with the DV tape from a Cannon DV camera. I feed the file from the camera via firewire connection to my computer in the "add media" section of Screenblast.
Bryan

laz wrote on 12/8/2003, 7:00 AM

I've found the only degradation to occur when ptt and then capturing same avi back again to re-edit is if my os is not 100%. This usually took the form of some frames getting pixellated. Once I'd sorted out the os it was ok.