Can Anyone Explain Why This Works?

[DVantrease]

I'm trying to understand why this works. I converted a DVD to MPG and the MPG file came out too big for 1 cd, about 840MB. Just for kicks, I loaded it into TMPGEnc's Mpeg Tools like I was going to 'cut' it, but WITHOUT actually cutting anything out I ran it thru, and the new file is only about 760MB, and it still plays perfectly! What I'm trying to understand is exactly what happened. What made it shrink by 80MB, did something get 'stripped out'?

Thanks guys

[jnunez]

Because you lowered the bitrate. Thats why.

[DVantrease]

I didn't lower the bitrate. It was left as a 'MPEG-1 VideoCD (non-standard)' and was not re-encoded.

[cmacleo]

You sometimes get this effect is there are MPEG errors. Various utilitiy program will cut the file at the corruption resulting in a truncated file. Was the 760Mb file complete (ie did it finish at the right point)?

[DOGLOOP]

Typically when you cut the *.mpg file in tmpgenc you can change block size & header & "padding" (a bit like a dummy file) ... these can affect whether or not the file is recognized as mode1... mode2 ... etc.
So, in short, this is really results oriented. & when i capture from my ati aiw & capture @ mpg1 1150 kb/s w/ 2 chl stereo & 352 x 240 i can cut the saved file in "tools" as vcd stream & all that it takes to make a compliant "stream" is changing the header values .... VIOLA!
hope this helps a bit, & I'm sure someone else may be able to expound further, but I don't have the time w/ all my dvd/vcd/svcd x(s)vcd ... mp3 ... dcisoz ... laserdisc ... etc projects I have goin'