Create DVD from mkv and retain size?

[elven]

Hi all,

I'm hoping someone on this board can help me with a weird problem...

Stated simply, I would like to turn a Matroska-video (MP4, AAC sound) into a regular Video-DVD (DVD-R, 4.4GB). I'm working on a Linux system (Ubuntu Gutsy), and there seem to be not too many tools able to read mkv-files at all.
One that I found is DeVeDe: Practical, easy to use, and achieves what I want to achieve, i.e. it turns my mkv-file into an iso, ready to burn (or creates to disk structure for me).

My problem is the following: The original mkv-video is about 4.4GB, so it is perfectly sized for an ordinary DVD-R. DeVeDe, however, reduces the size of my original video by more than 50%, although the "disk usage" bar says "101%" (of 4.7GB). Now, I know, this is just an estimation... but the resulting video is about 1.2GB!

I simply cannot believe that the quality of a 1.2GB-video is *not* far worse than a 4.4GB-MP4, no matter how good the encoding. So, I really would like to keep the original size (4.4GB) (as much as possible). Does anyone have any idea how I could achieve that? Can I increase the "video rate" (DeVeDe suggests 5001)? To what number? (I don't want to try different settings, as the process takes about 5 hours each time).

By the way, I also tried avidemux with about the same results.

Any ideas?
Thanks in advance,
Marcus

[guns1inger]

I am guessing, but the size of it, that this is a 720p source. To determine the bitrate you need, use abitrate calculator. I like Vcalc, however that is Windows only. The board calculator should run in any java capable browser, so start with that. You need to enter the running time of the video and the size of the disc (in this case the default will do) and it will tell you the bitrate you should be encoding at. 5000 sounds about right for a 2 hour movie with 192 - 224 kbps stereo audio.

Assuming that is the running time of the video, then obviously the encoder isn't using that bitrate. However, 1.2 GB is also right for a 30 minute video, so you need to work out what your video really is.

I have tried to fill in the gaps in your post with some assumptions that may not be correct. If they are, you will be reducing the resolution by 50%, and re-encoding, so there will be a quality hit. if I am wrong, well . . . . you need to fill in the missing details then.