Comcast announced last week it will offer lightning-fast Internet connections to about 1.5 million metro Atlanta homes starting next month. The speed would be twice what rivals Google and AT&T have said they will offer locally.

Some facts about the changing cable landscape in metro Atlanta:

What you could do with faster online speeds at home?

Comcast says it will offer 2 gigabit-per-second residential speeds in metro Atlanta. Google and AT&T have separately announced plans for 1 gigabit speeds in some local cities. Currently, many local Comcast customers get 50 megabit-per-second connections. (1,000 megabits make a gigabit.)

How fast would it take to download:

A full-length HD movie

• 2 gigabit = 12 seconds

• 1 gigabit = 24 seconds

• 50Mbps = 8 minutes

100 songs

• 2 gigabit = 2.4 seconds

• 1 gigabit = 4.8 seconds

• 50Mbps = 1 minute and 36 seconds

High-speed Q&A

Q: When will some metro Atlantans have access to the gigabit-per-second speed?

A: Comcast said the service rolls out next month and installations could take place within weeks. Neither Google nor AT&T has set a date for their own local service. Some business customers already have access to much faster speeds. And small areas are offering the service, such as on the Georgia Tech campus and at the Avalon development in Alpharetta.

Q: How much will the residential gig service cost?

A: Neither Comcast nor AT&T has disclosed pricing. Google has said prices will be roughly similar to offerings in other cities where the service is priced at $70 a month.

Q: Where are there likely to be at least two providers offering gigabit-per-second online connections in metro Atlanta?

A: Comcast is expected to rollout gig service to 1.5 million homes in metro Atlanta - the “vast majority” of the customers it serves. If you are looking for another option, here are the incorporated cities where Google and/or AT&T have said they will or may add gig service:

Alpharetta —- AT&T considering

Atlanta —- Google and AT&T

Avondale Estates —- Google

Brookhaven —- Google

College Park —- Google

Decatur —- Google and AT&T

Duluth —- AT&T considering

East Point —- Google

Hapeville —- Google

Lawrenceville —- AT&T considering

Lithonia —- AT&T considering

Marietta —- AT&T considering

McDonough —- AT&T considering

Newnan —- AT&T

Norcross —- AT&T considering

Sandy Springs —- Google, AT&T

Smyrna —- Google

Woodstock —- AT&T considering

Sources: Comcast, AT&T, Google, Arris Group of Suwanee

Source: Suwanee-based Arris Group