[mythtv-users] Hauppauge HD-PVR: Photos and link to pre-order

[Brian Phillips]

Craig Treleaven wrote:
> Am I the only one finding the gaga excitement about this device
> rather premature?  Unless I've missed it, we have no objective
> evidence of how well it works.  1080i is 1920 X 1080 pixels, 30 times
> a second.  At 3 bytes per pixel, that is 186,624000 bytes per second.
> (720P has about 11% less.)  Good quality H.264 is usually done in two
> passes and even high end PC's take several times live to give a
> tightly compressed, good quality result.     
> 
> They say their $250 device encodes in real time.  Does the quality
> suck or the compression?  Or both?  Are they throwing away 3/4 of the
> pixels from the start to get the data rate down to something the
> device can keep up with?  Do they have to take shortcuts with the
> compression meaning that we'll be burning hard drive space faster
> than Paris Hilton goes through personal lubricant?     
> 
> They've promised a lot and I hope they can deliver.  But I'll be
> skeptical until there are credible reports in from the field. 
> 
> Craig

Why does the quality or the compression have to suck?  They say it encodes
in real time, if that's the case, they're definitely not using an Intel/AMD
CPU running an OS.  I imagine it would be like most (almost all) real time
DSP devices.  It uses a hardware chip dedicated to h.264 encoding.  These
chips usually are clocked VERY slow, but can make up for that by using less
clock cycles to do more complicated tasks.  In one of my undergrad DSP
classes the professor showed us a cheap DSP we would be working with and
said it was clocked at a whopping 166 MHz.  We all laughed thinking our
calculators had beefier equipment.  He then said that it took a Intel/AMD
CPU on the order of 13 clock cycles to accomplish a single multiply
operation.  The DSP could do two simultaneous multiplies per clock cycle.

Surely you are not forgetting that most everyone on this list has a
real-time encoder card for their current SDTV setup.  No one's throwing away
bits there and the quality doesn't suck too bad... 

$250 sounds about right if all this device does is sample an analog stream,
encode, and pass the bits out the USB port.

Brian