Advice plz: what bitrate for ogm video transcoded to dvd?

[Nolonemo]

I have some anime files that are in .ogm format. I want to put them all onto a DVD.

The .ogm files are around 360MB for a 40 min video, so I figure that the bitrate for the video and 2 audio files in the .ogm wrapper is around 1000 kbps, therefore the video bitrate must be less. The video format is 640 x 480 (according to WMP when I play the .ogg files in it).

I've demuxed the audio using virtualdubmod and will transcode the video streams to elementary video stream m2v using Tmpgenc, then author to a single disk, convering the .wav audio to AC3.

Given the low bitrate of the originals, will it make a difference if I transcode to full DVD or half D1? Or should I stick to full D1 because the originals are 640x480?

I also don't know if a higher bitrate will make a noticable quality difference -- if I burn to DVD5, my video bitrate will have to be around 2200 kbps (taking into account AC3 audio and some overhead for menus), if I burn to DVD9, bitrate could go up to 4500 kbps. Given that the orignals have such a low bitrate will I see a difference?

Final question. I'm planning to use 2-pass VBR in Tmpgenc. How close to the average bitrate will the actual bitrate be (ie, how conservative do I have to be in setting the bitrate in Tmpgenc?). I don't want to transcode all the stuff and find out I'm a little over the size limit for whatever my target disk size is.

Thanks for your help.

[jimmalenko]

Given the low bitrate of the originals, will it make a difference if I transcode to full DVD or half D1? Or should I stick to full D1 because the originals are 640x480?

I'd go Full D1 - you'd be throwing away almost half your horizontal resolution if you used half D1, and by the sounds of the source, you need every bit of quality you can retain.

I also don't know if a higher bitrate will make a noticable quality difference -- if I burn to DVD5, my video bitrate will have to be around 2200 kbps (taking into account AC3 audio and some overhead for menus), if I burn to DVD9, bitrate could go up to 4500 kbps. Given that the orignals have such a low bitrate will I see a difference?

Bitrates need to be taken in context of the codec used. For example, you generally need roughly 3-4x the bitrate of Xvid/DivX when using MPEG-2 to get a comparable quality. IMO 2200 would be really scraping the barrel for Full D1 - even Half D1 would probably struggle. 4500 might just be OK for Full D1 if using 2-pass VBR.

Final question. I'm planning to use 2-pass VBR in Tmpgenc. How close to the average bitrate will the actual bitrate be (ie, how conservative do I have to be in setting the bitrate in Tmpgenc?). I don't want to transcode all the stuff and find out I'm a little over the size limit for whatever my target disk size is.

I'd subtract 100 off whatever a bitrate calculator gives you. This should provide plenty of room for basic menus. If you want motion menus, then you're gonna need to take off more.