If the image quality on your burned DVDs is poor, the cause is often a combination of the project resolution you used and the amount of MPEG2 compression required to fit the video on the disc. Projects use either NTSC (720x480) or PAL (720x576) resolution.
When you import your material, it is adjusted to fit whichever video standard is used for the project.

The original picture usually has a much higher resolution (unless the material is exported in High Definition).
The maximum number of pixels generated is based on the number of lines available in the TV standard.
The standard MPEG resolutions are:

• 704x480 pixels (TV NTSC)
• 704x576 pixels (TV PAL)
• 720x480 pixels (DVD NTSC)
• 720x576 pixels (DVD PAL)

The DVD player takes the video data and formats it for PAL or NTSC.
The DVD format uses MPEG2 video compression to ensure the video will fit on a DVD.
The longer the video is, the higher the compression ratio needs to be, and the more likely it is that the compressed video will contain artefacts. If additional compression is required to fit your video on a DVD, the resulting image quality may be poor.