# Can HDMI cause pixelation, freezing?



## dlfl (Jul 6, 2006)

Is it technically possible for an HDMI connection to cause pixelation and freezing that wouldn't be there with a component connection?

I just switched from HDMI to component out of my HD. I did this to eliminate the HDMI as a possible cause for a remote control lockup I sometimes have when I change channels and the TA/SDV system delays too long providing the correct frequency (my theory anyway).

It hasn't been long enough to reach any conclusions yet. I have had one instance where a channel took at least 10 sec. to tune. With HDMI, the remote control would have been locked up requiring power cycling the TV (not the TiVo) to recover. With component it didn't lock up and finally the channel tuned.

However I also have just a feeling (for now) that I'm seeing less pixelation and freezes on one of the channels (SCIHD) where I used to see occasional bad flare ups of this. This is an SDV channel -- the few channels where I do get pixelation and freezes are all SDV.

So, I'm wondering: Is there any theoretical basis for HDMI introducing pixelation or freezing that wouldn't be there with component? Perhaps a flaw in the TV's processing of the HDMI signal?


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## vccat (Oct 21, 2009)

If you have a bad HDMI cable or HDMI connection, it can degrade the digital signal and that could show up as blocks, sparkles or freezing unlike an analog component signal where you would see something wrong with the image long before it got so bad it started dropping out.


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## justen_m (Jan 15, 2004)

Are you using the Native video setting on your Tivo? Try switching to Fixed 1080i or Fixed 720p, whatever one matches your TV's actual resolution. Maybe there is a handshake issue going on over HDMI if you are changing channels between one that is 720p, 1080i, or 480i to one that is different resolution. It is a simple thing to try.

If the problem is only on SDV channels (I assume by this you mean standard def, 480i), perhaps your tv is just doing a poor job converting that resolution to your TV's native resolution. When this occurs over HDMI (which I think is a 2way channel, as opposed to all other channels being just 1way), perhaps the protocol stacks are failing or erroring out.


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## dlfl (Jul 6, 2006)

I'm using fixed 720p output.

SDV means Switched Digital Video. SDV is used for some HD and SD channels.

Pixelation and freezing are only occasional on a few SDV channels I watch, both SD and HD. I would think a bad HDMI cable would cause more trouble than that but ..... ? I have an identical HDMI cable that I use to connect a DVD player to the TV and the video is rock solid perfect with that source.

In my first post I left out another possible theory: problems with the TiVo circuitry that creates the HDMI signal.


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## justen_m (Jan 15, 2004)

dlfl said:


> In my first post I left out another possible theory: problems with the TiVo circuitry that creates the HDMI signal.


Ahh, got it. Well, I've got my TivoHD hooked up to my TV via HDMI and haven't noticed any pixelation or freezing, but my sources feeding the Tivo are OTA HD and analog cable. No cable cards or SDV here.

Perhaps there is a conflict with Tivo's HDMI chipset and SDV chipset? Without knowing system architecture, it is tough to say. Perhaps they are sharing the same bus and exceeding its max bandwidth. With component, you've got analog signals so it probably wouldn't share the same bus as SDV, but since HDMI is digital, perhaps it and SDV share the same one somewhere internally. Just theorizing here, sorry I can't be of more help.

[edit] However, you'd expect a lot more people having the same problem as you if this was a system architecture limitation. Have you tried swapping HDMI cables between Tivo and DVD player?


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## dlfl (Jul 6, 2006)

justen_m said:


> ........you'd expect a lot more people having the same problem as you if this was a system architecture limitation. Have you tried swapping HDMI cables between Tivo and DVD player?


Based on forum posts I suspect a lot of people using digital cable do have occasional pixelation and freezes on some of their channels. I just don't know how many of them have sorted out whether the HDMI connection plays a role. I think other causes are more likely suspects but just wondered what others thought, or if anyone actually knew if HDMI could cause such problems.

I'm watching IMUS on FBN right now and getting occasional glitches just like I did when using HDMI. FBN is an SDV SD channel and the RS errors are zero, as they always are when I get glitches. I suspect: (1) cable system encoding that the TiVo decoders just don't handle correctly or (2) some mysterious SDV problem such as the TWC Carolinas thread is working.


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## vccat (Oct 21, 2009)

If your seeing the same *digital* glitches like you did when using HDMI then you now know it was not the HDMI cable connection and must be the Cable channels or Tivo Tunner.

A problem with the analog component connection would not break up in the same way as digital.


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