HDMI cables do not send 1's and 0's!!! - Page 2 - AVS Forum
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post #31 of 36 Old 12-16-2011, 02:28 PM
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As I understand it, decryption simply consists of XORing 24 bits (8 bits from each channel) with a 24 bit number that changes with each frame. So, a single bit error should affect only one pixel in one channel.
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post #32 of 36 Old 12-17-2011, 10:16 AM
 
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Colm, very interesting. So one for one except if the 24 bit "seed" is changed. If the 24 bit seed is changed then the decode would affect every pixel but just in that frame?
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post #33 of 36 Old 12-17-2011, 02:31 PM
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I did a little reading to refresh myself on the subject. Apparently, a new 24-bit number is generated for each pixel. So an error in the 24-bit number would affect only one pixel. Whether it affects a single pixel or an entire frame, the likelihood of an error in that number is extremely remote in an otherwise properly operating device. The 24-bit number is not transmitted, it is generated locally by both the transmitter and receiver starting with the same seed. The receiver and transmitter compare results every 128 frames to ensure they are in sync.

Look here for more detail than you probably want.
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post #34 of 36 Old 12-29-2011, 10:05 AM
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I believe that ground issues in equipment can also inject imperfections into the signal path of copper cable that can manifest as artifacts. Could be a factor in what the viewer sees when comparing cables.
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post #35 of 36 Old 12-30-2011, 10:49 AM
 
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Quote:
Originally Posted by Kei Clark View Post

I believe that ground issues in equipment can also inject imperfections into the signal path of copper cable that can manifest as artifacts. Could be a factor in what the viewer sees when comparing cables.

Kei, But those artifacts should manifest themselves as a large imperfections not as subtle changes in color or contrast which require uniform changes in multiple pixels. In other words, any ground issue would result in random changes not coherent changes to only the low order bits.

BTW, thanks for the help you've provided on the various HDMI questions. It is always good to have another person who understands HDMI help out.
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post #36 of 36 Old 12-31-2011, 02:28 PM
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Quote:
Originally Posted by alk3997 View Post

Kei, But those artifacts should manifest themselves as a large imperfections not as subtle changes in color or contrast which require uniform changes in multiple pixels. In other words, any ground issue would result in random changes not coherent changes to only the low order bits.

BTW, thanks for the help you've provided on the various HDMI questions. It is always good to have another person who understands HDMI help out.

Agreed. I don't get arund to this forum much, will have to visit more often.
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