The team announced the moves Thursday via its official Twitter feed, but did not confirm any figures.
Another season was added to Seymour's contract so that the bonus can be prorated over the next five years, according to the report, and the defensive end will be under contract through the 2016 season.
The website reported that Huff's 2012 $4 million base salary also has been reduced to $700,000, and the remaining converted to a $3.3 million set to be combined with a pre-existing $4 million roster bonus to create a guaranteed $7.3 million bonus. Huff's contract was extended by two years, making him a Raider through the 2014 season.
Those two moves save the Raiders $11.82 million in cap space -- a huge number for a team that already has had to make a number of cost-cutting decisions. The Raiders currently are in talks with linebacker Kamerion Wimbley in hopes to restructure his deal, a source with knowledge of the situation recently told NFL Network insider Jason La Canfora.