I’ve been playing around with Slingbox a lot on my PC, Mac and Windows Mobile phone. There’s no doubt it’s a great product – my friend has even started to use my DVR to record and watch things remotely since he’s too cheap to get one!

Anyway, Sling’s video codec sometimes freaks me out when I’m beginning to buffer because it does something that I haven’t seen other codecs do – a pitch-invariant time stretch. Basically, it slows the whole video stream down without making it choppy or changing the pitch of the audio.

I’m assuming it does this to give itself time to buffer more video, avoiding some of the stutter-starts or blank pauses that other codecs suffer from – but the effect is a bit weird. Jon Stewart seems like he hasn’t had his coffee, theme songs are at a lower tempo… it’s just off enough to make me do a double take.

This only lasts for at most 20 seconds or so when I move from control mode into full streaming mode, so it’s certainly not a problem. I think more often than not it just makes me think, “Nice. Smart solution.” If they didn’t do this, transitioning from no-buffered, skippy-frame control-mode into the full streaming mode would be a lot less elegant.

Does anyone know if other streaming codecs use this technique?