[mythtv-users] HDHomeRun and jumpy video

Brian Wood beww at beww.org
Fri Sep 14 21:08:00 UTC 2007

Rich West wrote:
> Brian Wood wrote:
>> Rich West wrote:
>>> Dan Ritter wrote:
>>>> On Thu, Sep 13, 2007 at 10:48:18PM -0400, Rich West wrote:
>>>>> I've got a new HDHomeRun and a mediocre antenna set up which is showing 
>>>>> excellent signal quality on the major stations in the area.  However, 
>>>>> when those stations are viewed via mythtv, the video looks great except 
>>>>> for the fact that it seems to stutter about once a second.  One station 
>>>>> has the audio delayed by about a second, as well...
>>>>> Viewing through VLC is a little better, but not a whole lot....
>>>>> Before I go digging further, and possibly buying a better antenna, would 
>>>>> an antenna cause the stutter, or is this possibly a limitation of the 
>>>>> backend and/or frontend? (viewing via VLC is, obviously, direct to the 
>>>>> HDHR, whereas via mythtv it's going through the backend).
>>>> What's your hardware on the frontend? Have you had perfect HD
>>>> playback before?
>>> This is my first foray in to HD on this box other than playing DVD's or
>>> DivX/MPEG-4 HD video.
>>> The FE's have AMD64 3000+'s, 512MB RAM, local IDE drive, nVidia GeForce
>>> 6200.  The machines have always been rather bored.  Even when I was
>>> pushing HD during my tests last night, the machines were still bored...
>> Are you using nVidia's drivers? HD with the generic nv driver is
>> problematical.
>>> I guess I'll hit up RadioShack or something for a decent powered antenna
>>> vs the tiny thing I picked up at HomeDepot and give it another shot this
>>> evening.
>> Funny thing about digital TV: You either have it or you don't (sometimes
>> known as the "cliff" threshold).
>> If you have sufficient signal to watch it's unlikely a powered antenna
>> will help. Also remember than amplifiers amplify the noise as well as
>> the signal :-)
> Definitely using the nvidia drivers.
> Yup.. the advantage/disadvantage of being binary (1 on, 0 off). :)
> The antenna I picked up is this little powered antenna that is about
> 3.5" x 7" x 1/2".  It's ever so slightly bow shaped with a long (3ft)
> extendable antenna off of the back of it.  When I bought it, I figured I
> was only picking it up for testing/proof of concept.  Antennaweb shows
> all of the stations to be ~21miles from my house at 277Degrees (almost
> due-west).  I'm betting I probably need something a little more serious
> than this thing...

21 miles, if you are line-of-sight, should work OK with a basic indoor
antenna, maybe:

Something you get with a "better" antenna, in addition to more gain, is
better directionality (ie: rejection of "off-axis" signals). Sometimes,
even if you have adequate signal strength, you also have reflections
that are also of "adequate" strength to cause problems.

So a better antenna, even without amplification, can make a difference
even at what should be close distances.


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