[mythtv-users] HDHomeRun - Comcast shut off clear QAM

Andre Newman mythtv-list at dinkum.org.uk
Thu Dec 12 17:07:28 UTC 2013


On 12 Dec 2013, at 17:37, Michael T. Dean <mtdean at thirdcontact.com> wrote:

> On 12/12/2013 11:32 AM, Mike Perkins wrote:
>> On 12/12/13 16:05, Jay Ashworth wrote:
>>> From: "Michael T. Dean"
>>>> No, I mean, "VDPAU isn't guaranteed to work on all content, or with all
>>>> applications". VDPAU works great in MythTV on my PCIe GeForce GT220
>>>> (with CPU running in performance mode), but some content (such as that
>>>> from my NBC affiliate) trips it up, making video playback/watching with
>>>> VDPAU decode useless. And, since there's no way for me to tell MythTV
>>>> "only use VDPAU if the content came from channels other than this one,"
>>>> I need to use software decode (where /I/--or people smarter than me who
>>>> work on ffmpeg and MythTV video decoders can change and fix the
>>>> software). And, even if MythTV allowed me to only use VDPAU on content
>>>> from certain channels, I'd /still/ need a good CPU that can decode the
>>>> high-bitrate MPEG-2 in software--or else I couldn't watch Marvel's
>>>> Agents of S.H.I.E.L.D. So, while the Presentation portion of VDPAU is
>>>> wonderful, the Decode portion leaves a lot to be desired.
>>> 
>>> Oh, my.  I had no *idea* VDPAU was that sloppy.  Crap, and I just bought
>>> a new NV card. <sigh>
>>> 
>> It's not that VDPAU is sloppy, it's just that they can only code it to work with any examples they can get hold of.
>> 
>> It is obvious that although there are allegedly TV "standards" the variation possible inside those standards is so broad that examples will surface that no amount of existing coding can possibly deal with.
> 
> Right.
> 
>> 
>> The broadcasters don't care -- the TVs display them alright, don't they? Must be *your* problem, then.
>> 
>> The fact that VDPAU can't handle everything thrown at it is no different than what happens with ffmpeg -- various combinations of changes and/or corruptions in the input stream just can't be predicted or catered for in code up front. It takes someone to experience the problems, capture the offending stream, send it to the coders and for a fix to be added to the next release -- assuming anyone can be bothered, of course.
>> 
> 
> But the difference is that I can't change the silicon in my VDPAU-compatible card, nor can I change the code in the nvidia proprietary drivers, when the show I want to watch is encoded in such a way that VDPAU can't handle it.

Nvidia used to actively collect examples of non-working video, I sent them some early BBC HD stuff once. Do they still do that, did you submit an example of NBC's that shows the problem?


>  I can work on (or find someone else interested in working on) ffmpeg code.  And, by choosing a frontend system that can use, but doesn't have to use, VDPAU, I have options when I want to watch something that VDPAU can't handle.
> 
> Mike
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