Re: stutter on ABC 720p ATSC signals
- From: "JW" <JW@xxxxxxxxxxxx>
- Date: Wed, 3 Oct 2007 10:06:31 -0700
Yes, digital signals are much more sensitive to Multipath and back retroflection problems then analog tuners. Some people who have antennas in their attics have reduced these problem by shielding the antennas on the sides and the back. Because of this you see some antennas advertised as HD antennas that are not multipath sensitive, however, they are best only used when all the broadcast antennas are at the same location. Newer HD tuners have been designed to not be as multipath sensitive and they are starting to show up in some HD tuners. Your Tivo may have one of these new tuners.
From everything you have tried I think you have hit on the problem sinceMultipath problems can be frequency sensitive.
Graphic cards perform the hardware acceleration used to de-interlace and apply motion compensation for use with interlaced broadcasts by the decoders. However I don't think this is your problem since you have the latest Nvidia cards.
Did you use the following utility to change decoders in Vista?
http://mediacenterexpert.blogspot.com/2006/07/vista-media-center-decoder-utility.html
Have you tried one of the card vendors application yet instead of MC?
"David" <David@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:8464047B-C472-4CF9-B7BA-7532E296D3F7@xxxxxxxxxxxxxxxx
I have tried the direct run and I still get the same problems. I don't know
how to check if it's a multi-path issue or if that could even affect a
digital transmission.
I have am currently using HDHomeRuns but have an HDTV Wonder and an
Avermedia A180. All exhibit the same problem.
I have two sets running at 1080p and one at 720p but all have nVidia
graphics cards that are new (but purchased from diff vendors). Does the
graphics card/driver affect the decoding process?
I have tried the Cyberlink PowerDVD decoder and it has the same problem. At
one time, I thought Cyberlink made the MS decoder and if that's true then
maybe that wasn't a good test.
When I watch the recorded file, I keep thinking it's a decoding problem. It
most often (but not always) happens when the scene is changing say from a
commercial back to the main program or when the main program changes from one
scene to another like I see often in news programs. It doesn't seem to be
tied to the amount of action on the screen.
I guess I need to understand the elements involved in the decoding process.
Do you know who makes the MS decoder?
Is the graphics card and graphics card driver part of the decoding process?
Thanks for the help.
"JW" wrote:
The tuner in your TiVo probably has more sensitivity and interference
rejection capability then those in your PCs. So I suggest that you try
connecting only one of your PCs directly to the cable line to see the if
splitters or other connections you have in order to maximize signal strength
and reduce possible interference.
Also I suggest that if you have a different model graphics card available I
suggest you try it in one of the PCs. If an older card it might not hande
l1080i but hopefully it can handle 720p
What make/model tuner cards are you using?
Do you have the same problem if you are running the tuner card manufacturers
TV program instead of MC?
If you have another DVD Decoder on the system to can possibly switch to it
using the following utility.
http://mediacenterexpert.blogspot.com/2006/07/vista-media-center-decoder-utility.html
"David" <David@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:80689C2C-B77C-48A9-9C62-FBC6AC4D79DB@xxxxxxxxxxxxxxxx
> Thanks for the tips. I will try your suggestion.
>
> I am using the default decoder and my drivers are up to date.
>
> David
>
> "JW" wrote:
>
>> At the moment one thing I can think of is to call your ABC station and
>> see
>> if they are aware of any problems and/or go to the avsforum,.com >> local
>> HDTV
>> subforum for your city and see if there any threads there that may
>> assist.
>> ABC and Fox may be using different buffer sizes which is causing the
>> problem
>> only on Vista and not on your Tivo. Do you also have the latest Vista
>> drivers for your HDTV tuner card
>> I assume that you are using MS MPEG2 decoder which is the default on
>> Vista.
>>
>> "David" <David@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>> news:B37E9C0A-3E57-408D-8E15-B11AD3908A6E@xxxxxxxxxxxxxxxx
>> >I get the stutter in MP as well as MC. Actually, the stutter can >> >appear
>> > anytime even in scenes where the only thing changing is someone >> > moving
>> > their
>> > arm or walking from one side of the scene to the other. It can >> > happen
>> > when
>> > the viewing commercials that are 4:3 or in 16:9 full HD pictures.
>> > Quickly
>> > panning scenes on evening HD 16:9 shows can be flawless. The >> > symptom
>> > seems
>> > to have little reproducibilty when it comes to the amount of action >> > on
>> > the
>> > screen.
>> >
>> > I also have an HD Tivo pulling in ATSC and the picture is flawless >> > on
>> > ABC
>> > with this unit so I think it cannot be a station bandwidth issue.
>> >
>> > "JW" wrote:
>> >
>> >> Do you also get the stutter if you play a recording in MediaPlayer
>> >> instead
>> >> of MC?
>> >> Is the stutter in high action video such as sports or when panning >> >> a
>> >> scene?
>> >> If yes to both of these the problem is that your local ABC station
>> >> does
>> >> not
>> >> have enough bandwidth allocated to its "HD" station and it is not
>> >> transmitting all of the data so they are dropping frames during the
>> >> broadcasts.
>> >>
>> >> "David" <David@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>> >> news:4373F25B-CC2E-4743-8BDB-C9097EE13AC0@xxxxxxxxxxxxxxxx
>> >> > When watching ABC I get occasional stutters in the picture. The
>> >> > stutters
>> >> > are
>> >> > very slight and the sound does not stutter. I have 3 different
>> >> > computers
>> >> > and
>> >> > the stutters happen at the same exact place in the material on >> >> > all 3
>> >> > computers when viewing ABC.
>> >> >
>> >> > When viewing and if I rewind the buffer or recording, the stutter
>> >> > occurs
>> >> > at
>> >> > the same place each time. This seems to point to something in >> >> > the
>> >> > digital
>> >> > stream since it's always in the same place when you rewind and
>> >> > exaclty
>> >> > in
>> >> > the
>> >> > same place on the other computers watching ABC.
>> >> >
>> >> > All other stations are perfect, even FOX which is also 720p.
>> >> >
>> >> > Signal strength is well above 90%.
>> >> >
>> >> > The computers are running Vista Ultimate and are all Core 2 Duos >> >> > and
>> >> > have
>> >> > nVidia 8600GTS graphics cards with the latest drivers and the 4
>> >> > hotfixes
>> >> > MS
>> >> > and nVidia recommend.
>> >> >
>> >> > To me, it's as if the decoder, when reading the file, finds
>> >> > something
>> >> > it
>> >> > doesn't like in the video stream and simply skips over it. The
>> >> > stutter
>> >> > is
>> >> > very subtle but bugs the heck out of me.
>> >> >
>> >> > Any ideas?
>> >> >
>> >> > Thanks
>> >>
>>
.
- References:
- Re: stutter on ABC 720p ATSC signals
- From: JW
- Re: stutter on ABC 720p ATSC signals
- From: David
- Re: stutter on ABC 720p ATSC signals
- From: JW
- Re: stutter on ABC 720p ATSC signals
- From: David
- Re: stutter on ABC 720p ATSC signals
- From: JW
- Re: stutter on ABC 720p ATSC signals
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- Re: stutter on ABC 720p ATSC signals
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