Why are my DVDSP DVDs low quality?

[jbaugh]

I have been making QT movies using Photo to Movie. I start with high resolution photos (i.e, 2400 X 1600) and then save the slideshow to HD DV (1081i) setting with Width set at 1140 and Height set at 1080. The quality setting is set to highest quality. I am very impressed with the resulting QT movie when played on my computer monitor. They are nothing short of spectacular and I would love to be able to share them with distant friends. The QT movie usually weighs in at about 20 GB in size for a 25 minute movie.

When I build a DVD with DVDSP, I am quite surprised to find that there is only about 1.2 GB of data on the final DVD. Most of the DVD is not used. The quality of the movie when viewed from the DVD on my new HD widescreen television is very disappointing. The image sharpness is much less than when viewed as a QT movie.

What is happening here? Why is DVDSP compressing the data so much? Is this why my final DVDs are poor quality? Would my DVD be higher quality if DVDSP used more of the 4.7 GB capacity of the DVD? Or is this just the nature of the beast? The limitations of the technology.

Is there anything I can do to produce high quality sharp slideshow movies when viewed on a HD TV screen? Or will I have to wait for the capability to burn true HD DVDs?

Any suggestions will be greatly appreciated.
John

[jagabo]

NTSC DVD is limited to 720x480 frame size. That's about half the resolution in each dimension compared to your QT file.

[Case]

When downscaling from 1080 (HD DV) to 480 (DVD NTSC), you loose 55% of your detail in vertical direction. I think you may "have to wait for the capability to burn true HD DVDs" to retain all your glorious detail.

[jbaugh]

Wow!
Thank you jagabo and Case. I barely clicked the "Submit" button and I got two responses.

Your answers make very good sense and I'm even embarrassed that I asked such a simple question now.

Does this mean that I will get just as good a quality with my DVDs (in terms of TV viewing) by making 720 X 480 QT movies as I do with the much larger file size of the 1440 X 1080 QT movie?

There are two other movie formats available with Photo to Movie:
1) DV Widescreen (NTSC) Width 720 Height 480
2) HD DV 720 Width 1280 Height 720

For my stated use and purpose would I be better off exporting the Photo to Movie projects with one of these formats?

My ultimate goal was to make the same high quality movie that I see on my computer with my 20 GB QT movie available for others to view. I quess this is just not practical with current levels of technology.

Thanks for your patience with my ignorance.
John

[jagabo]

Widescreen DVD would give you the same resolution issues. HD DV would give you something closer to the resolution of your source but will be very large.

You should look into creating low frame rate MOV files at high resolutions without transitions. That should allow you to use codecs like Motion JPEG and have each image only encoded once within the file. For example, you could create a 2400x1600 MJPEG MOV file at 0.125 frames per second. Each frame would be displayed for 8 seconds. The total file size would only be the sum of the JPEG images.