size differs ... i wonder why?

[mp3]

hi everyone,

i have a question to anyone who possibly knows an answer to this:

a few days ago i've burned a vcd out of an ~430mb mpg file. everything went well and it played just fine on my standalone. nevertheless, when i take a look at the .dat file on the cd, it turns out to be just about 370mb .. so i wonder if this is correct, as i don't want to live with a possible quality loss in the end ...

pls enlight me

thx in advance

[shochan]

it almost sounds like file oevrhead. Im not really sure. but once the file is made unless your burning software uses a seperate mpeg encoder than it will be the same as when you made it.

[mp3]

thx for your reply shochan,

if i get you right, you think that it has sth to do with the header of the mpg (maybe more than one header in the original mpg)? this would explain the different size (oh and btw. original size was 417megs, instead of 430, sorry), but i wonder if you could notice this somehow during playback on a pc media-player.
furthermore, i used nero to create the vcd and if i'm right nero uses his own plugin to convert mpg -> vcd. maybe that is the problem? ...and if so, are there better appl. out (like vcdgear/vcdeasy ...)?

thx in advance

[LeeBear]

I think you just answered your own question mp3. If you are using Nero and have standard compliant turned on it'll re-encode your MPEG to make the stream VCD compliant if it's not compliant (ie. 1150 CBR, 352x240/288). Your MPEG source was probably encoded wtih a non VCD standard bitrate (higher) and that's why the size is larger. To maintain the best quality possible it's best to not re-encode MPEGs since MPEG encoding is lossy, so everytime you encode you degrade the quality. If your DVD player can handle non standard bitrates it's best that you turn off 'standard compliant' in Nero.

-LeeBear

[mp3]

thx for your proposal LeeBear,

but i've tried it again with nero, and after i've unchecked 'standard compliant' button and drag and drop the file over it is ~370mb still (specs of the video are 352x240, 29.97, even the running time is equal) ... could it be that it is normal for a vcd to use a better compression, comparing to normal mpeg's (... u know like it is with burning an svcd on a 700mb disc, where u could store ~800megs)?
...or do u know some other good application to burn vcd's except nero, so i could check if it's the file or the application here?

thx

[LeeBear]

Ah I think I've figure out what you mean now. How are you getting these file sizes from? When you make a VCD it's written in CD-ROM 'mode 2' that means that the CD is written without error correction and the entire space of each sector is used to store the data, in this case the MPEG file in dat format. This is why you can normally only put 700 MB of data on a 80 minute CD but you can put 800 MB of data on a 80 minute CD when making a VCD. When windows reports the file size from the CD I believe it doesn't take this into account hence you get the reported size of 370MB for your dat file which is about 15% smaller then your 430MB original MPEG. 15% is approximately the extra amount of data that writing in 'mode 2' allows you to put on a CD, 800MB is about 15% more then 700MB. I think that should explain it.

-LeeBear