Mpeg 1 renders

rossf wrote on 9/18/2002, 4:15 AM
Hello,I've been doing some looping media and graphics for fundraising dance parties and have been rendering them as mpeg1 as I don't have a dvd burner,for installation type work the render is not bad but does anyone have any advice on improving Mpeg1 renders ?I notice small detail gets pretty compressed,I don't expect dvd quality but how can I tweak a bit to get the best out of Mpeg1 renders.thanks

Comments

mikkie wrote on 9/18/2002, 10:13 AM
There are several different codecs available for mpeg1, as well as different compression levels - changing either of these might help.

Mpeg1 itself is more of an editing format nowdays, with each frame stored separately. Mpg2, mpg4, realmedia, & winmedia all discard a lot of the picture that at least in theory remains the same from frame to frame. Using these formats you will actually lose more data, but because of the higher compression, you'll be able to maintain a higher data rate and so your picture quality will actually improve -- I'd say drastically if you're using mpg1 currently.

Mpg2 files will be a bit larger then the other formats, but it is easier to set a higher data rate to get less artifacts, and there are a lot of settings that you can fine tune. The other formats are much more efficient, but depending on the source, it can get really difficult to eliminate every bit of picture degradation.
John_Cline wrote on 9/18/2002, 10:37 AM
MPG1 does not store each frame separately. It is a difference-based encoding scheme just like MPEG2.

As far as improving the quality of MPG1 renders, just increase the bitrate. The VCD spec has a fixed bitrate, but if you're not making VCD's to play on a set-top DVD player, then you can increase the bitrate. I believe the upper limit is somewhere around 4 megabits/sec, although that limit may have just been an aribitrary limit imposed by the MPG1 encoder I was using. Nevertheless, increasing the bitrate will increase image quality. This is true of practically all video compression formats (except DV which has a fixed bitrate.)

John
mikkie wrote on 9/19/2002, 10:43 AM
Hey John

apologies - Semantics may have gotten me... ie: open an avi encoded with picvideo, morgan, matrox etc. in whatever and there will be the same number of keyframes as there are frames, & I've always seen these formats referred to as both mpg1 & mjpg1 - the latter is actually more correct, & I'd gotten lazy about it.

Panasonic among others have mpg1 encoders that do basically the same type of compression as mpg2 etc. - you are right - VCD as a distribution format just hadn't occured to me or been mentioned (that compression format is somewhat primitive comparred to what's out there today, there isn't as much VCD activity in the U.S, & frankly I haven't renderd anything that way for some years now).

We're both right I think re: upping the bit rate. Whilst far from an expert, if I remember correctly, there are some extensions to the VCD spec besides SVCD that do allow higher bit rates but might not be recognized in all players. Also, encoders do/did vary -- again if memory serves, the panasonic encoder was slower but favored for quality over LSX, and if the mpg2 renders are any indication, then the lsx encoder might be superior to mainconcept at lower bit rates, at least as far as artifacts.