Questions about video resolution, and bitrate

[jay_lubb]

Hi, all.

I've been compiling a snowboarding dvd from several hundred (yes, hundred!) mpgs. I use TMPGEnc DVD sorce creator, then DVD author.

When I load the mpgs into the dvd source creator, and go to make the final mpg to be authored, I see these options, and was wondering about them:

1) video resolution - initially, the mpg videos are 352x240 pixels. Would it affect the video quality to change it to a higher resolution, or should it stay the same 352x240 pixels. If I leave it at 352x240 pixels, would the picture quality suffer because the mpg is being encoded again?

2) bitrate - obviously, a higher bitrate = better picture quality than a lower bitrate. At what point is the picture quality going to suffer? What is the lowest (in your opinion) bitrate that will still be decent picture quality?

I apologise in advance if these questions seem dumb, or if they are confusing. I'm new to all this, please bear w/me.

[redwudz]

If Your videos are that low of resolution, there's not a lot you can do to improve them. Considering that's VCD resolution, and a VCD uses 1150Kbps, I would leave them as is and not re-encode as long as they are otherwise DVD compliant. You could check their bitrate with Gspot 2.70 and see what they presently are.

[mats.hogberg]

1) If you resize, you have to reencode. So, leaving them at 352x240 pixels would be best, as that's a NTSC DVD std resolution.
2) The same again. If your source mpgs can be autored as is, as DVD, (they are DVD compliant - see What is DVD top left) then that's the best you're ever gonna get.
But some rules of thumb:
352x240: ~2000 kbps
352x480: ~4000 kbps
720x400: As high as possible, ~6000 kbps
But what's in the video also matters. Talking heads don't need much. High action or shaky video (where lots is different between individual frames) needs high bitrates.

/Mats

[natural_mystic]

excellent information. thanks!