[pvrusb2] Maybe what a I really want is a Hauppauge HD PVR!?

[Mike Isely]

On Sun, 25 May 2008, roger wrote:

> 
> You're right, it seems to export the live stream via USB?

Of course.


> 
> But, noticed this within the Specs:
> "Note: the playback of high definition H.264 requires a fast CPU and at
> least 256MB of graphics memory"

That's because decoding h.264 is expensive in terms of CPU and memory.  
Note that it says _playback_.  The device and its driver are all about 
recording; the system is "on its own" for playback (i.e. device and 
driver are not involved).  This is true for any PVR setup except when 
using a Hauppauge PVR-350 with the ivtv driver (that device has mpeg2 
hardware _decode_ abilities but it runs out of gas once you get past SD 
quality).  The thing about this device is that since it encodes to a 
more 'expensive' format, then anything which plays back the captured 
video is going to need a lot of horsepower.


> 
> Is the only difference between the two newly released ATSC recorders,
> one exports MPEG2 and the other exports h.264 (aka MPEG-4 AVC)?  (Also
> noting the additional connectors for in & out processing.)

The HD-PVR also lacks a tuner.  The HD-PVR has component video inputs.  

The HVR-1950 is basically a souped up PVR-USB2 - same basic analog side 
as before plus a digital tuner.  Like the older PVR-USB2, the HVR-1950 
can also do composite / s-video capture, but HD quality streaming is 
limited to digital reception via its tuner.  (In other words it can tune 
and stream HD RF signals but it can only still hardware encode SD.)  
HD-capture is in the domain of the HD-PVR.  The HVR-1950 is the intended 
replacement for the PVR-USB2.  The pvrusb2 driver now handles the 
HVR-1950 - analog *and* digital sides.  Documentation for this is still 
forthcoming but the driver works now.  Unfortunately I probably won't 
get a chance to work on the documentation today due to a silly family 
commitment :-)

The HD-PVR by itself isn't a digital receiver.  But it's an ideal device 
when paired with an HD tuner that has HD outputs via component video.  
It solves the problem of linking up MythTV to a DRM-infected cable box.  
(At least I think it does, I have no personal experience with this.)  
This is why the MythTV crowd is drooling over it.  It just needs a Linux 
driver.

An absolute killer device would be an HD-PVR with a tuner and FM 
reception.  That would make it a complete HD-level evolution over what 
the PVR-USB2 was.  But I have no idea if anything like that is in the 
works.


> 
> 
> Guess I'll have to wait awhile to see the results of recording on lower
> processor platforms.

I'm sure you can use a very slow processor to record with the HD-PVR.  
It's playback that is the issue.  And the root cause has to do with 
h.264 decoding, so it isn't going to get any better with driver 
improvements.  More likely this will be less of an issue in the future 
and processor power improves.  It's the same sort of thing that happened 
and HD tuners started to appear and the computers of the day could 
barely handle the decoding requirements.  Nowadays just about any decent 
computer can do it.

  -Mike

-- 

Mike Isely
isely @ pobox (dot) com
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