Request Advice for creating DVDs from 7.5 gig file sizes

Question

Hi,
[using dvdstudio 3]
I’m looking for advice for home DVD project i'm working on. I want to create a DVD from video that has been captured to my computer using iMovieHD, and have completed my wanted edits for two clips. They are about an hour-plus each. When exporting the two clips separately (Sharing, in iMovie terms), the file sizes are about 7.5 Gig each at full quality,and I understand I’m going to have to cut some corners in the process to get both on one DVD and I’m even willing to have two DVDs, but still need to know the best way to decrease the file size for each one. The audio should remain as 16 bit 44.1 Khz, Stereo.
I’m wondering what the best method to achieve an optimum quality DVD is. Again, I realize I’ll have to compress the video at the loss of quality (i.e., “cut corners”) to make the DVDs.
In my previous experiences, I’ve retained the larger file size all the way up through the authoring process in DVD Studio letting it build a 7.5 gig dvd format (VIDEO_TS). Then, I used DVDx2One to compress it down to 4.5. The end result was pretty good and I never had any troubles per say. However, this project is important to me and I want to make the best quality I can. What would you do differently?
Here are my software tools that I use interchangeably for previous projects; copying, authoring, editing, etc:
-> iMovieHD 4x – used to capture the video.
-> DVD Studio 3 - to author and build my dvd session
-> ffmpegx - as a video conversion and compression tool
-> DVDX2one to recompress DVD formatted (VIDEO_TS).
Thanks very much for your tips!
JeffTronics

Answer 1

Hi Jeff - is the iMovie file in QT format?
If so, you need to compress it to MPEG2 - you don't need to suffer too much of a quality loss by doing so - how long (in minutes) is the video?
You should also encode the audio to AC3 - this will save loads of space as AC3 is about a tenth the size of a .aiff.
ffmpeg will create the MPEG for you, but so will DVDSP (as indeed will Quicktime). In your applications folder you should find 'A.Pack' which will handle the audio conversion as well.
The exact encoding parameters you use will depend on the nature of the footage that you have got - it's more than just squeezing it to fit - you need to account for fades, pans, zooms and fast action as well. Some parts can have a lower bitrate applied than others, and this is where a tool such as Compressor comes in handy. DVDSP will encode the footage as you work, or when you build if you want it to - this is also a reasonable option if you have nothing else available, or if you are new to the whole thing.
The best workflow is to go from iMovie to a compression tool to create your MPEG2 file. Take the associated .aiff file and encode to to Dolby Digital (AC3). Import both the MPEG2 and the AC3 file into DVDSP and you should be able to get the entire project to less than 4.37GB (the maximum capacity of a DVD-R).