Hey Steven,
Short answer:
If good quality HD films could be stored on DVDs they wouldn’t have needed to come up with blu-rays. Even that requires a dog choking amount of compression.
Long answer:
You can’t fit a watermelon through a hole the size of a lemon without squeezing some juice out of it. So you are going to loose quite a bit of quality trying to get that 90 gig file down to 4.5 gigs. What you mean by loosing it’s “HD Quality” I’m not quite sure. As “HD” only really refers to the display dimensions of the image…and loosely at that since it can (usually) mean 1920×1080 or 1280×720.
Compressing it as an h264 MOV using FCP, Quicktime Pro, Compressor, Adobe Media Encoder or whate have you will give you a good looking file that is much smaller. However, if it probably won’t fit down to the size you need unless make the quality settings at around medium or lower. Which might not give you the result that you want.
If you really need to transport the file at a reasonable quality your best bet is going to be a pocket USB hard drive. Or squeeze it down to about 14 gigs and dump it onto a cheap SD card. :/
Keep in mind that your master file is probably an Apple ProRes and that it won’t be playable on most computers. So you do need to convert it to a different codec. And don’t overlook the audio settings. An hour long uncompressed stereo audio track can eat up a lot of space. AAC would probably be your best bet.
This will get you a good looking file that is much smaller. Still not small enough to fit on a DVD I’m afraid.
VIDEO
Compression: H264
Quality: Medium to High (Don’t bother with best it will make a file of similar size to your master)
Key frame rate: Automatic
Frame Reordering: Yes
Dimensions: 1920×1080 or 1280×720 (If displaying on a TV I find that 720 scaled up to 1080 looks better than 1080 with aggressive compression)
SOUND
Format: AAC
Sample Rate: 44.1
Channels: Stereo
Bit Rate: 128 kbps
Prepare for internet steaming (NO)
Hope this helps, buddy.
– Drew