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playatim
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Join Date: Jul 2012
Posts: 9

How Does High Def. Sync with TVs Capabilities?

11/13/2012 8:12 PM

does anybody know how cable boxes communicate with high def tvs to show correct mode? My hdmi out of cable box is 1080i and just got a set for repair that only accepts 720p signals. is it reduced in main board of set or supposed to tell box to down convert?
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Joshi
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Join Date: Oct 2007
Location: India
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#1

Re: How Does High Def. Sync with TVs Capabilities?

11/14/2012 1:55 AM

How cable boxes communicate with high def tvs to show correct mode?
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playatim
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Join Date: Jul 2012
Posts: 9
#2

Re: How Does High Def. Sync with TVs Capabilities?

11/14/2012 11:34 AM

when connected to cable box this set shows noise then nothing, but have hdmi adapter on computer w a manual selector set to 720p pic shows normally.
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Wal
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Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#3

Re: How Does High Def. Sync with TVs Capabilities?

11/15/2012 3:51 AM

Connect your cable box to your monitor using AV cables, I suspect your box has AV sockets too...

Go to the menu of your cable box via the on screen display (with your remote) and see if the HDMI interface has some options in the setup panes.

If you were able to find a way to alter the HDMI to 720 V 1080 you can can then test the HDMI cable connection.

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playatim
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Join Date: Jul 2012
Posts: 9
#4
In reply to #3

Re: How Does High Def. Sync with TVs Capabilities?

11/15/2012 10:24 AM

so nobody gonna answer the question? already knew this
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Anonymous Poster #1
#5
In reply to #4

Re: How Does High Def. Sync with TVs Capabilities?

11/15/2012 3:36 PM

I can't tell you how, but I can tell you that I have to turn my TV on first and it signals the cable box what its resolution is. Then, I turn the cable box to on from standby, and it sets itself to the TV resolution.
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Anonymous Poster #2
#6

Re: How Does High Def. Sync with TVs Capabilities?

11/15/2012 5:42 PM

Communication channel protocols

HDMI has three physically separate communication channels, which are the DDC, TMDS and the optional CEC.[81] HDMI 1.4 added ARC and HEC.[82][83]

[edit]DDCMain article: Display Data Channel

The Display Data Channel (DDC) is a communication channel based on the I²C bus specification.[84][85] HDMI specifically requires support for the Enhanced Display Data Channel (E-DDC), which is used by the HDMI source device to read the E-EDID data from the HDMI sink device to learn what audio/video formats it supports.[81][84][85] HDMI requires that the E-DDC support I²C standard mode speed (100 kbit/s) and allows optional support for fast mode speed (400 kbit/s).[86]

The DDC channel is actively used for High Definition Content Protection.

From Wikipedea http://en.wikipedia.org/wiki/HDMI

My understanding of is that the A/V format is decided during handshake between the box and the tv when the connection is first made
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playatim
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Join Date: Jul 2012
Posts: 9
#7
In reply to #6

Re: How Does High Def. Sync with TVs Capabilities?

11/15/2012 7:51 PM

so that means its not communicating with the box, problem could be w either, but since it also doesnt sink w mine its probably a problem w the main board on tv. thank you
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