Sources say the fat lady has sung: Toshiba will be killing off the HD DVD format in a matter of weeks, after retailers' decisions to stop carrying hardware and software using the format have left it with no other choice.

For the record, Toshiba officially states that no decision has been made, but that the company is "studying the market impact and the value proposition for consumers" of HD DVD.

But the writing is pretty clearly on the wall. Since the beginning of 2008, Blu-ray discs have outsold HD DVD discs at a rate of 3 to 1. With more and more retailers opting not to stock HD DVD equipment and movies, there's just no way that number is going to go up. (Even the HD DVD fire sale and a $2.7 million Super Bowl ad don't seem to be helping.) While previous analysts have guessed that HD DVD would survive through the holiday season of 2008, it looks like Toshiba is ready to call it quits and move on to greener pastures. It's said the company now loses several hundred dollars on each HD DVD player sold.

The only real question remaining is how soon the announcement could come, and what the remaining backers of HD DVD will do when it does. How quickly will Paramount and Universal be able to switch production from HD DVD to Blu-ray? And what will Microsoft, a longtime HD DVD supporter, do? Fodder a-plenty for future blog posts, I'm sure.

Meanwhile, I'm happy to kick off the official date of death pool for HD DVD right here. My guess: March 7. (Why? Toshiba's fiscal year ends on March 31, and it will want to take the huge writeoff it has coming before the end of the year. March 7 gives it enough time to set things up for a rebound in 2008... probably making Blu-ray equipment and eating humble pie.)

Post your death date prediction in the comments section below. Winner gets bragging rights until Sony jacks Blu-ray prices up an extra 20 percent in celebration of its big win. Yay!

(Update: Wal-Mart announced it's going Blu-only today, too. Come on, Toshiba!) 

LINK: Toshiba to drop HD DVD, sources say