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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Jan 24, 2010 4:32 pm Post subject: My dumb HD question of the day |
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So... I was spending some quality reading time in the bathroom this morning, with a copy of the 'Absolute Sound' from 2007, where they reviewed a number of flat screens. THis is the era where many flat screens couldn't accept a full 108p HDMI signal, but the panel itself was 1920 X 1080 and upconversion was done internally.
Reading the specs, I noticed something interesting. All HDMI input specs were 37Mhz for the video bandwidth. Why? Why then are us analog guys trying to find 150Mhz specs, and Mike is modding boards beyond that?
I'm missing something.. what is it?
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Sun Jan 24, 2010 5:09 pm Post subject: |
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Uh, compression in the codec?
CJ
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Sun Jan 24, 2010 5:19 pm Post subject: |
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| cmjohnson wrote: | Uh, compression in the codec?
CJ |
Compression codec? I thought HDMI was transporting uncompressed. Damn boat keeps missing me. 
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sun Jan 24, 2010 5:21 pm Post subject: |
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How about the simple explanation. The HDMI speed is a digital signal and the latter is an analog signal.
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Sun Jan 24, 2010 5:22 pm Post subject: |
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If the video format is 1080p @ 24Hz the bandwidth will be alot lower than 1080p @ 60Hz. The digital stuff will work with the low refresh inputs.
Scott
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Jan 24, 2010 5:31 pm Post subject: |
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The specs don't say in the review. Would I be wrong to assume that at say 720p/60, the video bandwidth of a digital set needs to be the same as an RGB analog input?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sun Jan 24, 2010 5:39 pm Post subject: |
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One more time. The speed of HDMI is in Gbit/s............
720p/1080i 8-bit is 742.5 Mbit/s per channel, 1080p 8-bit is 1.65 Gbit/s per channel, 1080p 12-bit DC is 2.23 Gbit/s per channel and so on.
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Mon Jan 25, 2010 11:21 am Post subject: |
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| macgyver655 wrote: | One more time. The speed of HDMI is in Gbit/s............
720p/1080i 8-bit is 742.5 Mbit/s per channel, 1080p 8-bit is 1.65 Gbit/s per channel, 1080p 12-bit DC is 2.23 Gbit/s per channel and so on. |
You know, the 'one more time' is what it took. 
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Trust no one. Absolutely no one. Advice of the board.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Mon Jan 25, 2010 3:53 pm Post subject: |
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Mac, call me stupid, but I still don't understand.
I looked at the review again, and it says: H bandwidth 37 Mhz.
Oh, and this is on component as well as HDMI.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Jan 25, 2010 3:56 pm Post subject: |
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| Curt Palme wrote: | Mac, call me stupid, but I still don't understand.
I looked at the review again, and it says: H bandwidth 37 Mhz.
Oh, and this is on component as well as HDMI. |
You got a make and model on the one being discussed? I want to read it before I comment. Something else doesn't make sense in your first post.
Last edited by macgyver655 on Mon Jan 25, 2010 3:56 pm; edited 1 time in total
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Mon Jan 25, 2010 3:56 pm Post subject: |
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Let me get it in a bit.
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Mon Jan 25, 2010 10:54 pm Post subject: |
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Here's another possibility: See all those pins on the HDMI connector? Or DVI connector? There are multiple data streams running on
the cable. Each individual one of them may be no more than 37 MHz but the aggregate bandwidth may be much higher.
CJ
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