Hi, sry for the noob question, but what is cable overhead meant for?
DP1.2 has 17.28 Gbit/s with overhead removed, but it actually has 21.6 Gbit/s. Whats the point in even advertising it if its not usable? Can you use all 21.6 Gbit/s for raw pixels x color x refresh ?
what is cable overhead for?
Re: what is cable overhead for?
From the Wiki page:
http://en.wikipedia.org/wiki/DisplayPor ... ifications
8b/10b encoding provides DC-balancing and Embedded Clock within serial channel (10 bit symbols, 20% coding overhead)
This means that for every 8 bits that are transmitted, there will be actually 10 bits flying over the wire. This is usually done for error-correction purposes. With any electrical signal, it is always possible that a bit is flipped by mistake during normal usage. The error-correction can find and correct some simple cases where a bit has been flipped by mistake.
I just read on the wiki-page that Display Port uses packets, just like most network technologies. So every frame that is being sent needs a header. That will take a little overhead too.
Besides video, Display Port can also send audio-signals. Not sure if bandwidth is reserved for that. I think HDMI can also do Ethernet over its cable alongside with video and audio signals. Not sure if Display Port can do that too. But that might take some bandwidth as well.
But the biggest overhead is the 8bit/10bit encoding.
http://en.wikipedia.org/wiki/DisplayPor ... ifications
8b/10b encoding provides DC-balancing and Embedded Clock within serial channel (10 bit symbols, 20% coding overhead)
This means that for every 8 bits that are transmitted, there will be actually 10 bits flying over the wire. This is usually done for error-correction purposes. With any electrical signal, it is always possible that a bit is flipped by mistake during normal usage. The error-correction can find and correct some simple cases where a bit has been flipped by mistake.
I just read on the wiki-page that Display Port uses packets, just like most network technologies. So every frame that is being sent needs a header. That will take a little overhead too.
Besides video, Display Port can also send audio-signals. Not sure if bandwidth is reserved for that. I think HDMI can also do Ethernet over its cable alongside with video and audio signals. Not sure if Display Port can do that too. But that might take some bandwidth as well.
But the biggest overhead is the 8bit/10bit encoding.