Eddie Vedder, Jeff Ament, Stone Gossard and Mike McCready helped define the Seattle sound that became known as grunge rock. Their band, Pearl Jam, became one of the hottest groups of the last quarter century.

Now the band, which added drummer Matt Cameron, also of Soundgarden, in 1998, is 20 years in and marking the anniversary with a special documentary, “Pearl Jam Twenty,” crafted by filmmaker and rock journalist Cameron Crowe.

The film will premiere nationwide Friday, Oct. 21 at 9 p.m. on PBS (check local listings) as part of the first PBS Arts Fall Festival.

Crowe had access to more than 1,200 hours of Pearl Jam archival footage to put together the fim. The soundtrack for “Pearl Jam Twenty” will be released Sept. 20 via Columbia.

The PBS excerpt reveals how the seminal Seattle band formed and features “Footsteps” from the original Momma-Son demo tape that Vedder sent to Stone Gossard as his audition for the band.

The intimate video for “Thumbing My Way” features the band’s acoustic rendition of the 2002 “Riot Act” concert favorite.

With access to over 1,200 hours of Pearl Jam archival footage, Crowe has pieced together an inside look at a band that shaped an entire genre of music.

The soundtrack for ‘Pearl Jam Twenty’ will be released Sept. 20 via Columbia. You can pre-order the album now either as a CD or a download through amazon.com by clicking the link at left. The CD sells for $16.99.