Back when I ran a business that competed with TVEyes and Critical Mention, I used up to 8 analog tuners in a single box to record channels. Happauge PVR-150 and PVR-500 (2 tuners in one card).

Nowadays, it's harder because you can't get many of the necessary channels via analog. You need the decryption of a digital box (imagine several cable boxes stacked on top of each other) to grab the video and even then, it's difficult to get the closed captioning. This makes the colocation complexity more expensive and many facilities would just say "um, no thanks, we're not running a cable line in here for that."

As someone who used to work at Critical Mention I can speak a little bit to this. The infrastructure was set up about 9-10 years ago and initially involved one very dedicated engineer driving around the country installing DVR's at the different affiliate stations in almost all (if not all) 210 DMA's. These DVR's would "phone" in with video, as well as close captioning text to the datacenters. Over the course of the last 10 years the stack has changed a few times, but more recently the real time processing occurred as a series of Python lookups queued in Rabbit MQ. The resultant data (Close captioning text as well as Schedule, Demographic, Affiliate) information was indexed in a full text search cluster. Creating a searchable set of all TV video across 90 days is an engineering feat in and of itself. That being said I don't think any companies have been able to mine the data, summarize or aggregate it in any way that can be truly beneficial to a brand.

It's actually a fun and interesting real-world distributed computing problem. You need computers w/ TV tuners in every major market across the country in order to get the _local_ broadcast news. The computers then FTP the data back to the central servers.

But you can't easily/cheaply get server racks in 100 cities that have cable TV lines going into the cages.

So you have to find reliable places to put all your distributed computers that have good TV signals, good upstream bandwidth, a person who can help reboot it when it crashes, and reasonable cost.

Silicondust sells some network tv tuner devices that are very usefull, I've used the home version, HDHomeRun device a few times, and it looks like thay have some big rack mounted ones that would be well suited for this sort of purpose.

http://www.silicondust.com/products/models/tech3-8us-2x4/

Lots of storage + Lots of I/O throughput + Lots of software defined radios

MythTV allows you to record multiple channels on the same multiplex in the DVB world.

http://www.snapstream.com/ (I assume it's not cheap.)