Q: How To Watch Cable TV On My iMac?

If the settop box has s-video, component, or composite connections then you can get adapters to hook up that way.  But you are not going to get HD quality and you cannot use the HDMI outputs from the settop box due to HDCP copy protection.

Navigate to www.elgato.com, they have exactly what you need.

Elgato is not what he asked for.  He wants to connect his comcast box to his TV, not an alternative to receiving from another service or OTA.

1) I do not have HDMI but do have component connections. My TV is "720" resolution. Are you saying I won't get 720 on my iMac? (I cannot accept a lower resolution.)

Sorry you cannot do it, no HD.  Thank the entertainment industry for that. 

2) If I wanted to purcahse the adaptors, what would I search on? Say I go to Amazon; what search term would I use?

Google search for the kind of adapter you are looking for.  For example, if you decided to use component connection then google for say, "component video adapter for mac" (or other appropriate combination of words).  Apple also has a page that includes various adapters:

Monitor and display adapter table

Based on what he's told us this looks like it would work OK.

http://www.elgato.com/elgato/na/mainmenu/products/EyeTV-Hybrid-10/product1.en.ht ml

That device is basiclly similar to their OTA device.  If comcast was passing the local channels through their box unscrambled (QAM) it may (or may not) work.  But I think they scramble everything now.  This forced every comcast customer who didn't have a settop box (or DTA converter) to get one from comcast.

If you use OTA (over the air, antenna) or I think their service (I think they have one) then you can use those devices to record.  But there's no getting around the HDCP trying to use the HDMI output from comcast's settop box.

"It's interesting. It claims "high definition" but what that means is anyone's guess."

where I live all channels which call themselvs HD are 720P

havent come  across true ota 1080P

How about using a Slingbox?  Then you can view your cable tv from any computer anywhere (Assuming an internet connection.).

Rudegar wrote:

 

where I live all channels which call themselvs HD are 720P

havent come  across true ota 1080P

And you are not going to.  No OTA is 1080p (in the US, don't know about other countries that use the same system)  There are locals that use 1080i however.  They can do that if they only use a single subchannel and don't have to worry about splitting the bandwidth among multiple subchannels.

I think many CBS stations don't have multiple subs so they broadcast 1080i.  On the other hand I heard ABC specifically uses 720p because they think it looks better for sports events. 

The Elgato Eye TV HD does exactly what you're asking for.

I run my Bell Digital Set top box to my EyeTV HD via component cable and get full HD on my Mac.

I choose channels via the digital box and remote.

(ElGato has a remote system, but it;s skittish and dependent on what digital box you have; the EyeTV itself, however, coupled with the bundled EyeTV3 software is pretty trouble free and performs well.)

Unless Comcast has some encryption method that only your TV can decode, there should be no problem.

And why should there be? You paid for your service. Who's to say what screen you should choose to watch it on?