Question about codecs.

[troy]

I have an avi file that was captured from my minidv camcorder and edited and made a short avi clip with premiere. I tried to use avisynth to open the file and avisynth would not open it in mediaplayer or CCE. It said missing dvsd codec. I then read somewhere where I was missing the panasonic codec. So I installed this codec and now my avi files will open with mediaplayer and CCE. When I try to use Avisynth filters I need to have a command converttoyuy2() before the filters or the files will not open. It seems obvious that panasonic codec is taking over these avi files and panasonic is RGB so I need this converttoyuy2() before the filters to make them work.

I just do not understand how this codec gets associated with my avi file.

Is it possible to associate a different codec with my avi file.

What kind of quality loss or gain am I going to get with having this codec associated with my avi files.

Also I do not understand really what the deal is with these codecs. Can anyone shed some light on the subject.

[bb]

The Panasonic codec is similar to Microsoft's directshow filter, but it's a VfW codec. A limitation of this codec is, that it outputs RGB only. If you open type-2 DV AVIs through AviSynth's AviSource command, or if you open the file in any VfW application like VirtualDub, the fourCC code decides which codec to use. Most DV codecs, e.g. Panasonic or MainConcept, use "DVSD" as fourCC (Canopus is an exception: "CDVC").

To work with AviSynth the Panasonic DV codec is inconvenient, because DV uses YUV2, and most filters use YUV2 as well. With the Panasonic codec you'll convert to RGB inside the codec, but have to convert back immediately to YUV2 again because of AviSynth filtering. The colorspace conversion takes time, but you probably won't notice a quality difference, because the rounding errors implied with the conversion are minimal.

To work with AviSynth, I recommend to deinstall the Panasonic codec and install another one; many people use MainConcept or Canopus. With the latter you'll have to take care of the special fourCC, so you may have to change it in the AVI header. For both codecs there are free trials available. For decoding purposes you don't need anything else, but for encoding you need to buy the full version, else you'll get a logo imprinted in the video.

bb