source quality

[smokingweed3000]

Hey
Why is it impossible to keep the source quality in VCDs and SVCDs?
Thanks

[Anonymous65]

Because the *maximum* resolution of VCD is 352x240 and SVCD is 480x480. If you go from analog to digital, you loose detail and information in the A/D process, and you loose even more information in the ~100:1 data compression done with mpeg. As you know from sound, you have to sample twice that of the highest analog frequency component to reproduce the signal when going from analog to digital and back to analog again. Similar is the case with analog to digital video. Sample at 704x480 to make a VCD at 352x240 will give you the best reproduction of a VHS tape that has a resolution of about 320x480 pixels. Doing an oversample of more than 2x will not gain you much. Some people say stay away from multiples, but my experience is not so. 2x oversamplig works fine and is faster to convert.

[Kdiddy]

Because in most cases you are taking away the bitrate & resolution from the source...you can never TAKE AWAY parts of the original and still expect to have the same characteristics as the original...example, DVD to standard VCD..DVD bitrate is ~5+ mbps, VCD 1.15 mbps...that's a minimum 75% reduction in bitrate, some times more, ...now in standard SVCD cases, you only cutting the bitrate by 1/2....and there I can understand comparisions to maintaining some DVDesque qualitites, but not all...bottom line, the only truly way to keep source quality or near source quality...IMO, is to maintain 65%+ of the original source if not all.

PS - "puff puff pass, you babysitting the joint over there"

<font size=-1>[ This Message was edited by: Kdiddy on 2001-12-29 13:57:10 ]</font>