2 ms·

Not on a monitor (that I'm aware of), but it is a major feature of signal distribution equipment for installed AV and broadcast. A large part of the delay that

Not on a monitor (that I'm aware of), but it is a major feature of signal distribution equipment for installed AV and broadcast. A large part of the delay that you are seeing is from EDID negotiation and HDCP. This happens of the 100kbit/s DDC channel and requires a bit of back and forth. On the above systems this is pre-negotiated so that switching can take place across a single frame. A lot of that equipment is likely price prohibitive for desktop use, but you may be able to reduce the time a little with sidestepping that process either in your machine setup or with an external bit of lower cost hardware like and EDID emulator (e.g. https://www.extron.com/product/edid101h4kplus https://www.extron.com/product/edid101h4kplus).

mort96 4y ago
100kbit/second is still blazing fast for communication which ought to be on the order of a hundred bytes... 4 seconds at 100kbit/s is 50kB. Why does it have to be so chatty?
- kimburgess 4y ago
  When the input is first selected here's will be a hot plug detect, EDID request and an EDID response. That response can be up to 32kB so anywhere up to ~2 seconds depending on how many extension blocks are in use by the display. Here's a nice breakdown on more of what happens there: https://research.nccgroup.com/wp-content/uploads/2020/07/hdmi_-_hacking_displays_made_interesting.pdf https://research.nccgroup.com/wp-content/uploads/2020/07/hdm.... When a suitable set of image parameters have been agreed HDCP (may) then step in to ruin your day. Again a nice walkthrough of that is available here: https://blog.cryptographyengineering.com/2012/08/27/reposted-cryptanalysis-of-hdcp-v2/ https://blog.cryptographyengineering.com/2012/08/27/reposted.... As other commenters have correctly noted, there's definite room for improvement. One thing to remember though is this involves hardware that can be in operation for the order of decades so there's a lot of cruft that accretes in order to maintain compatibility. Frankly it's mildly impressive that for the most part all the above happens in silence and continues to (mostly) work.

mort96 4y ago

100kbit/second is still blazing fast for communication which ought to be on the order of a hundred bytes... 4 seconds at 100kbit/s is 50kB. Why does it have to be so chatty?

kimburgess 4y ago
When the input is first selected here's will be a hot plug detect, EDID request and an EDID response. That response can be up to 32kB so anywhere up to ~2 seconds depending on how many extension blocks are in use by the display. Here's a nice breakdown on more of what happens there: https://research.nccgroup.com/wp-content/uploads/2020/07/hdmi_-_hacking_displays_made_interesting.pdf https://research.nccgroup.com/wp-content/uploads/2020/07/hdm.... When a suitable set of image parameters have been agreed HDCP (may) then step in to ruin your day. Again a nice walkthrough of that is available here: https://blog.cryptographyengineering.com/2012/08/27/reposted-cryptanalysis-of-hdcp-v2/ https://blog.cryptographyengineering.com/2012/08/27/reposted.... As other commenters have correctly noted, there's definite room for improvement. One thing to remember though is this involves hardware that can be in operation for the order of decades so there's a lot of cruft that accretes in order to maintain compatibility. Frankly it's mildly impressive that for the most part all the above happens in silence and continues to (mostly) work.