Is it Better to Reduce Bitrate or Shrink the DVD?

[doggyofone]

I have 3 AVI files, all XVID, all AC-3, total 2.2 gig. If I use a higher bitrate I3 avi's won't fit a 4.7 DVD. If I reduce <3000 bits, I can fit. If I go to higher and use DVD shrink I can fit.
Which way is best, lower bitrate or shrink an MPEG with a higher bitrate?
I'm sure dual layer is best, but they cost!

[redwudz]

I would reduce the bitrate. Using Shrink might be OK in this type of situation if you just need to go down a little, but using the right bitrate is a better solution.

Another option is to use 1/2 D1 format if you need to make the best use of the bitrate available. A lot would depend on the quality of the video you are converting.

[yoda313]

Well another option of course is to buy a divx dvd player. You can get them for around $50 USD nowadays. That way you just burn the avi's as is without reencoding.

[doggyofone]

redwudz, what is 1/2 D1 format?

[kschang]

Normal rez for DVD video is 720xwhatever (NTSC vs PAL's vertical rez) You could encode video for 1/2 of horizontal rez, or 360xwhatever, and DVD will still play it, and you will save a bit on the bitrate.

[doggyofone]

NTSC is normally 648x486. If I reduce to say 324 x 243, how does this change my bitrate setting? Do I double?

[redwudz]

What kschang said. And if you look to the upper left for 'What is' DVD, you will see the different compatible formats for a DVD, including 1/2 D1. Generally when you end up with a bitrate down around 2000-3000, 1/2 D1 will do a better encode than full D1.

Take a 5 minute representative clip from your video and try it both ways. It works very well for VHS quality video or your 'average' Xvid, but saves a lot of space by being able to use a lower bitrate.

EDIT: This is the NTSC DVD format

720 x 480 pixels MPEG2 (Called Full-D1)

352 x 480 pixels MPEG2 (Called Half-D1, same as the CVD Standard)

Leave the bitrate the same as you calculated it for Full-D1, but use 1/2 D1 format. It makes better use of the bitrate available. Try it.

[doggyofone]

I'll encode with CCE at 352x480 and check the results. Bitrate for the original avi encode I set at 3000. The AVI is a quality file, but just over 3 hours, so the final result is crammed onto 4.7.
Thanks for the help.

[TBoneit]

NTSC is normally 648x486. If I reduce to say 324 x 243, how does this change my bitrate setting? Do I double?

NTSC has no connection to resolution. DVD supports certain resolutions only IE 720 by 480 or 704 by 480 or 352 by 480 or 352 by 240.

[doggyofone]

I gave this a try. Seems to be working OK.
Thanks for the help and lesson!