i am currently using the Panasonic converter for my vcds. What im still having trouble with is learning what gop is best for what. I have been using the default setting as im afraid to make the quality worse if i try one of their other settings. Does one(im assuming their default) give just a "general" use. Can anyone tell me (more so in laymens terms) what kind of film would i use the other gops offered on the Panasonic for? thanks

-- Doug (mazinz@aol.com), December 29, 1999

Answers

Hi Doug

GOP's????? I think you should leave it as the default setting because I think its a fixed specification just like the number of IPB frames for white book compliance.

Panasonic seem to have some options that can be changed and they do not appear to be included in the vcd spec. Other encoders lock out any changes once vcd is selected. Its too easy in this game to end up with a non compliant vcd (who cares some would say). Panasonic already produces "2 Channel" sound that is not compliant. I suggest you be careful and remember the changes may only suit your system and not play elsewhere.

I tried mucking about but found the default settings as good as I could get. You could play with filtering but I found "none" was best for my souce material and I got more benifits in better image quality by changing the source codec for the encode (applied to my Panasonic, LSX and DVmpeg5 encoders).

The best quality of vcd for me has resulted by converting my full frame DV or analogue captures/edited vision to the Intel 5.11 at 100% quality with a prime frame every frame. MP4 (v2) at 6000kb/s is a very good source also. Few of us have the disk space to use uncompressed files as the source for anything other than three or four minutes of video.

My Philips DVD does not play the increased data rate vcd's that people have talked about on this site as a way of providing a better image. However, I am yet to try/see if the DVD MPEG-1 (SIF) spec will actually play from a vcd (available in LSX version 3).

Certainly the computer players will play out of spec stuff so I guess it depends on what your aiming at.

Ligos have a very interesting paper on Mpeg in general at:

http://www.ligos.com/support/

and that is worth a read even if you have not got the LSX encoder.

Perhaps hardware encoders provide the best increase in image quality, but no one is saying much about that here.

The quest for better quality is a problem after you have made a choice of equipment that may not be just right but until you see someone elses you never know how good or bad your product actually is.

Here is a comment on the best I have seen and been striving to reach:

Analogue edited DV vision (svideo) captured at 352 x 288 PAL (instead of full frame) with an old Matrox "rainbow runner" card. The achieved data rate in the test was just under 1.3M/s or about 10000kb/s.

Cheers, have a good 2Ky change over!

-- Ross McL (rmclennan@esc.net), December 30, 1999.