Best quality mpeg 2 encoding software / approaches?

[Dave Friend]

“The lower the number the higher the quality, but also bigger
file sizes. ideally you would want the smallest GOP possible.”

Not necessarily. Small GOP (down to an all I frame structure) only looks good when you have a high enough bit rate to make decent pictures. It’s a bit rate higher than allowed by the DVD spec to be certain. Also, picture quality will will often improve with a longer GOP at the data rates that are typical of a long-form (feature length) DVD. Even if you are not filling the disc and can run at or near the max rate for a DVD there are advantages to using at least a moderate sized GOP.

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