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

Scott D. Davilla davilla at 4pi.com
Tue Apr 8 01:17:21 UTC 2008


>On 4/7/2008 2:14 PM, Steven Adeff wrote:
>>>   > What would also be cool is a dual encoder version (ala PVR-500)....
>>>   >
>>>
>>>   Buy two. ;)
>>>    
>>
>>  haha, touche. but seriously.... extra power, extra shelf space, etc.
>>  The HD-Homerun could have been a single tuner device too with the "buy
>>  two" option. even the PVR-500 did not have to exist. But why not lower
>>  the footprint and include two devices in one box, sharing one power
>>  supply, one USB cable, etc.
>>  
>
>MPEG 4 encoding is extremely CPU intensive.  To date there are no chips
>that can encode two streams of raw HD data.  With the size and price
>point Hauppauge has aimed for it wouldn't be cost effective to have a
>dual device.  Even the highest performance TI DSP can't encode two HD
>streams simultaneously (although it can encode a stream and decode
>another at the same time).  That isn't to say that someday there will
>not be a dual device.  Remember the PVR-500 came out *several* years
>after the single tuner Hauppauge PVR cards.
>

The Hauppauge HD-PVR is based on a chip from Ambarella. It's not a 
fast DSP that give realtime H.264 encoding but custom asic (think 
fpga on steroids). That's hardware based parallel processing, much, 
much faster than any cpu or dsp around. Custom asic hardware tends to 
be very fast but very specific function in this case a reatime H.264 
encoder. We do hardware with a fpga here at work. It been amazing to 
watch the progress in computational power over that last few years. 
Orders of magnitude increases in raw computational power and number 
of logic cells.

Ambarella also makes encoding chips for HD cameras. In Sept 2007, 
they came out with a SoC (system on chip) that makes it easy to 
create something like the Hauppauge HD-PVR USB device (it's not a 
card, it's a box). I bet that the Hauppauge HD-PVR is based of their 
SoC chipset. The Ambarella web site does not mention any dual stream 
chipsets so a dual encoder would be much harder for Hauppauge to 
implement. In addition, you also have to factor the USB connection. A 
single USB data stream is much easier to implement than a dual USB 
data stream even though USB can handle multiple data streams.





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