Monitor wakeup lag
Ever since I have seen computers, a flat monitor took a short while to turn on after the computer starts sending a signal. Usually this time is somewhere between one and a few seconds. That's the case when switching the computer on, when resuming it from standby, and when waking it after the monitor has gone idle and switched off. Back in the analogue days of VGA, I always thought it was because the flatscreen needed to adjust to the analogue signal to scan and digitise it correctly. Like an auto-adjust every time. But I don't get how this should be required for digital signals like DVI or HDMI.
Also, at the same time, internal notebook displays never had that delay. They turn on instantly and show the image right from the start. They've always been connected on a digital protocol, so that can work without a delay, too.
Why do external monitors still have that delay?
display
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
add a comment |
Ever since I have seen computers, a flat monitor took a short while to turn on after the computer starts sending a signal. Usually this time is somewhere between one and a few seconds. That's the case when switching the computer on, when resuming it from standby, and when waking it after the monitor has gone idle and switched off. Back in the analogue days of VGA, I always thought it was because the flatscreen needed to adjust to the analogue signal to scan and digitise it correctly. Like an auto-adjust every time. But I don't get how this should be required for digital signals like DVI or HDMI.
Also, at the same time, internal notebook displays never had that delay. They turn on instantly and show the image right from the start. They've always been connected on a digital protocol, so that can work without a delay, too.
Why do external monitors still have that delay?
display
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
This is very broad in the sense of all the different types and brands of equipment, as well as levels of technological advancement within those pieces of equipment. Is there a specific issue you are trying to overcome?
– CharlieRB
Sep 9 '14 at 10:59
I can imagine it's a broad topic. But it basically exists on every desktop computer and you can experience it yourself if you don't sit in front of a laptop. No specific issue though.
– ygoe
Sep 9 '14 at 15:07
Laptops are not using DVI so they have an easier time decoding the signal. DVI still needs to be decoded into the screen's native input signal.
– Kevin Panko
Sep 10 '14 at 4:52
add a comment |
Ever since I have seen computers, a flat monitor took a short while to turn on after the computer starts sending a signal. Usually this time is somewhere between one and a few seconds. That's the case when switching the computer on, when resuming it from standby, and when waking it after the monitor has gone idle and switched off. Back in the analogue days of VGA, I always thought it was because the flatscreen needed to adjust to the analogue signal to scan and digitise it correctly. Like an auto-adjust every time. But I don't get how this should be required for digital signals like DVI or HDMI.
Also, at the same time, internal notebook displays never had that delay. They turn on instantly and show the image right from the start. They've always been connected on a digital protocol, so that can work without a delay, too.
Why do external monitors still have that delay?
display
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
Ever since I have seen computers, a flat monitor took a short while to turn on after the computer starts sending a signal. Usually this time is somewhere between one and a few seconds. That's the case when switching the computer on, when resuming it from standby, and when waking it after the monitor has gone idle and switched off. Back in the analogue days of VGA, I always thought it was because the flatscreen needed to adjust to the analogue signal to scan and digitise it correctly. Like an auto-adjust every time. But I don't get how this should be required for digital signals like DVI or HDMI.
Also, at the same time, internal notebook displays never had that delay. They turn on instantly and show the image right from the start. They've always been connected on a digital protocol, so that can work without a delay, too.
Why do external monitors still have that delay?
display
display
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
asked Sep 9 '14 at 9:25
ygoeygoe
79721531
79721531
This is very broad in the sense of all the different types and brands of equipment, as well as levels of technological advancement within those pieces of equipment. Is there a specific issue you are trying to overcome?
– CharlieRB
Sep 9 '14 at 10:59
I can imagine it's a broad topic. But it basically exists on every desktop computer and you can experience it yourself if you don't sit in front of a laptop. No specific issue though.
– ygoe
Sep 9 '14 at 15:07
Laptops are not using DVI so they have an easier time decoding the signal. DVI still needs to be decoded into the screen's native input signal.
– Kevin Panko
Sep 10 '14 at 4:52
add a comment |
This is very broad in the sense of all the different types and brands of equipment, as well as levels of technological advancement within those pieces of equipment. Is there a specific issue you are trying to overcome?
– CharlieRB
Sep 9 '14 at 10:59
I can imagine it's a broad topic. But it basically exists on every desktop computer and you can experience it yourself if you don't sit in front of a laptop. No specific issue though.
– ygoe
Sep 9 '14 at 15:07
Laptops are not using DVI so they have an easier time decoding the signal. DVI still needs to be decoded into the screen's native input signal.
– Kevin Panko
Sep 10 '14 at 4:52
This is very broad in the sense of all the different types and brands of equipment, as well as levels of technological advancement within those pieces of equipment. Is there a specific issue you are trying to overcome?
– CharlieRB
Sep 9 '14 at 10:59
This is very broad in the sense of all the different types and brands of equipment, as well as levels of technological advancement within those pieces of equipment. Is there a specific issue you are trying to overcome?
– CharlieRB
Sep 9 '14 at 10:59
I can imagine it's a broad topic. But it basically exists on every desktop computer and you can experience it yourself if you don't sit in front of a laptop. No specific issue though.
– ygoe
Sep 9 '14 at 15:07
I can imagine it's a broad topic. But it basically exists on every desktop computer and you can experience it yourself if you don't sit in front of a laptop. No specific issue though.
– ygoe
Sep 9 '14 at 15:07
Laptops are not using DVI so they have an easier time decoding the signal. DVI still needs to be decoded into the screen's native input signal.
– Kevin Panko
Sep 10 '14 at 4:52
Laptops are not using DVI so they have an easier time decoding the signal. DVI still needs to be decoded into the screen's native input signal.
– Kevin Panko
Sep 10 '14 at 4:52
add a comment |
1 Answer
1
active
oldest
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Most external monitors will have processors to convert several potential sources such as DVI, HDMI and VGA to the monitor panels native signalling method or LVDS, for the panel electronics itself to convert to a native signal.
Most external monitors also have built in OSDs that need software to control it and inject it into the video stream.
These things need some kind of software/firmware to setup and control the digital signal processors, analog to digital converters (for VGA) and so on. The delay is not in the conversion of video from one standard to another (which can be done with a delay of less than 30ms per frame if memory serves) but is in the time to properly set up each processor in the pipeline in the correct order.
All of this is missing on a laptop display panel. The only control you have on a laptop is the backlight, all the picture brightness and contrast controls are done by the graphics card itself and not the monitor panel. The graphics card is essentially connected directly to the panel and already speaks the display panels "native" language with no intermediate processors to set up or conversion to take place.
External monitors also have independent power supplies unlike a laptop display. Power supplies take a few hundred milliseconds to a couple of seconds to switch to a high power state upon detection of a valid signal on one of the inputs. Usually a minimal set of electronics is kept alive when the display panel is off with the PSU in an efficient "standby" mode if you will.
Detection of the input signal also has a delay involved. Each input must be monitored or polled on a regular basis to check whether there is a valid signal and depending on the method this could be another couple of hundred milliseconds.
This gives you a generic set of steps for an external monitor:
- keep monitor PSU in low power state (standby)
- wait for valid digital/analog signal (only a small amount of electronics alive to reduce power)
- upon detection of valid signal switch the PSU on to high power mode
- power up analog and digital signal processors
- OSD processor
- Screen backlight switch on
- switch in whichever input was selected or has a valid input
- show picture
For a laptop the series of events is much smaller. The moment you hit the power button everything is immediately put into a high power state, including the display so the whole chain is effectively reduced to:
- pump video data at display panel.
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
add a comment |
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1 Answer
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Most external monitors will have processors to convert several potential sources such as DVI, HDMI and VGA to the monitor panels native signalling method or LVDS, for the panel electronics itself to convert to a native signal.
Most external monitors also have built in OSDs that need software to control it and inject it into the video stream.
These things need some kind of software/firmware to setup and control the digital signal processors, analog to digital converters (for VGA) and so on. The delay is not in the conversion of video from one standard to another (which can be done with a delay of less than 30ms per frame if memory serves) but is in the time to properly set up each processor in the pipeline in the correct order.
All of this is missing on a laptop display panel. The only control you have on a laptop is the backlight, all the picture brightness and contrast controls are done by the graphics card itself and not the monitor panel. The graphics card is essentially connected directly to the panel and already speaks the display panels "native" language with no intermediate processors to set up or conversion to take place.
External monitors also have independent power supplies unlike a laptop display. Power supplies take a few hundred milliseconds to a couple of seconds to switch to a high power state upon detection of a valid signal on one of the inputs. Usually a minimal set of electronics is kept alive when the display panel is off with the PSU in an efficient "standby" mode if you will.
Detection of the input signal also has a delay involved. Each input must be monitored or polled on a regular basis to check whether there is a valid signal and depending on the method this could be another couple of hundred milliseconds.
This gives you a generic set of steps for an external monitor:
- keep monitor PSU in low power state (standby)
- wait for valid digital/analog signal (only a small amount of electronics alive to reduce power)
- upon detection of valid signal switch the PSU on to high power mode
- power up analog and digital signal processors
- OSD processor
- Screen backlight switch on
- switch in whichever input was selected or has a valid input
- show picture
For a laptop the series of events is much smaller. The moment you hit the power button everything is immediately put into a high power state, including the display so the whole chain is effectively reduced to:
- pump video data at display panel.
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
add a comment |
Most external monitors will have processors to convert several potential sources such as DVI, HDMI and VGA to the monitor panels native signalling method or LVDS, for the panel electronics itself to convert to a native signal.
Most external monitors also have built in OSDs that need software to control it and inject it into the video stream.
These things need some kind of software/firmware to setup and control the digital signal processors, analog to digital converters (for VGA) and so on. The delay is not in the conversion of video from one standard to another (which can be done with a delay of less than 30ms per frame if memory serves) but is in the time to properly set up each processor in the pipeline in the correct order.
All of this is missing on a laptop display panel. The only control you have on a laptop is the backlight, all the picture brightness and contrast controls are done by the graphics card itself and not the monitor panel. The graphics card is essentially connected directly to the panel and already speaks the display panels "native" language with no intermediate processors to set up or conversion to take place.
External monitors also have independent power supplies unlike a laptop display. Power supplies take a few hundred milliseconds to a couple of seconds to switch to a high power state upon detection of a valid signal on one of the inputs. Usually a minimal set of electronics is kept alive when the display panel is off with the PSU in an efficient "standby" mode if you will.
Detection of the input signal also has a delay involved. Each input must be monitored or polled on a regular basis to check whether there is a valid signal and depending on the method this could be another couple of hundred milliseconds.
This gives you a generic set of steps for an external monitor:
- keep monitor PSU in low power state (standby)
- wait for valid digital/analog signal (only a small amount of electronics alive to reduce power)
- upon detection of valid signal switch the PSU on to high power mode
- power up analog and digital signal processors
- OSD processor
- Screen backlight switch on
- switch in whichever input was selected or has a valid input
- show picture
For a laptop the series of events is much smaller. The moment you hit the power button everything is immediately put into a high power state, including the display so the whole chain is effectively reduced to:
- pump video data at display panel.
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
add a comment |
Most external monitors will have processors to convert several potential sources such as DVI, HDMI and VGA to the monitor panels native signalling method or LVDS, for the panel electronics itself to convert to a native signal.
Most external monitors also have built in OSDs that need software to control it and inject it into the video stream.
These things need some kind of software/firmware to setup and control the digital signal processors, analog to digital converters (for VGA) and so on. The delay is not in the conversion of video from one standard to another (which can be done with a delay of less than 30ms per frame if memory serves) but is in the time to properly set up each processor in the pipeline in the correct order.
All of this is missing on a laptop display panel. The only control you have on a laptop is the backlight, all the picture brightness and contrast controls are done by the graphics card itself and not the monitor panel. The graphics card is essentially connected directly to the panel and already speaks the display panels "native" language with no intermediate processors to set up or conversion to take place.
External monitors also have independent power supplies unlike a laptop display. Power supplies take a few hundred milliseconds to a couple of seconds to switch to a high power state upon detection of a valid signal on one of the inputs. Usually a minimal set of electronics is kept alive when the display panel is off with the PSU in an efficient "standby" mode if you will.
Detection of the input signal also has a delay involved. Each input must be monitored or polled on a regular basis to check whether there is a valid signal and depending on the method this could be another couple of hundred milliseconds.
This gives you a generic set of steps for an external monitor:
- keep monitor PSU in low power state (standby)
- wait for valid digital/analog signal (only a small amount of electronics alive to reduce power)
- upon detection of valid signal switch the PSU on to high power mode
- power up analog and digital signal processors
- OSD processor
- Screen backlight switch on
- switch in whichever input was selected or has a valid input
- show picture
For a laptop the series of events is much smaller. The moment you hit the power button everything is immediately put into a high power state, including the display so the whole chain is effectively reduced to:
- pump video data at display panel.
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
Most external monitors will have processors to convert several potential sources such as DVI, HDMI and VGA to the monitor panels native signalling method or LVDS, for the panel electronics itself to convert to a native signal.
Most external monitors also have built in OSDs that need software to control it and inject it into the video stream.
These things need some kind of software/firmware to setup and control the digital signal processors, analog to digital converters (for VGA) and so on. The delay is not in the conversion of video from one standard to another (which can be done with a delay of less than 30ms per frame if memory serves) but is in the time to properly set up each processor in the pipeline in the correct order.
All of this is missing on a laptop display panel. The only control you have on a laptop is the backlight, all the picture brightness and contrast controls are done by the graphics card itself and not the monitor panel. The graphics card is essentially connected directly to the panel and already speaks the display panels "native" language with no intermediate processors to set up or conversion to take place.
External monitors also have independent power supplies unlike a laptop display. Power supplies take a few hundred milliseconds to a couple of seconds to switch to a high power state upon detection of a valid signal on one of the inputs. Usually a minimal set of electronics is kept alive when the display panel is off with the PSU in an efficient "standby" mode if you will.
Detection of the input signal also has a delay involved. Each input must be monitored or polled on a regular basis to check whether there is a valid signal and depending on the method this could be another couple of hundred milliseconds.
This gives you a generic set of steps for an external monitor:
- keep monitor PSU in low power state (standby)
- wait for valid digital/analog signal (only a small amount of electronics alive to reduce power)
- upon detection of valid signal switch the PSU on to high power mode
- power up analog and digital signal processors
- OSD processor
- Screen backlight switch on
- switch in whichever input was selected or has a valid input
- show picture
For a laptop the series of events is much smaller. The moment you hit the power button everything is immediately put into a high power state, including the display so the whole chain is effectively reduced to:
- pump video data at display panel.
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
answered Sep 14 '14 at 20:23
Mokubai♦Mokubai
56.9k16135153
56.9k16135153
add a comment |
add a comment |
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This is very broad in the sense of all the different types and brands of equipment, as well as levels of technological advancement within those pieces of equipment. Is there a specific issue you are trying to overcome?
– CharlieRB
Sep 9 '14 at 10:59
I can imagine it's a broad topic. But it basically exists on every desktop computer and you can experience it yourself if you don't sit in front of a laptop. No specific issue though.
– ygoe
Sep 9 '14 at 15:07
Laptops are not using DVI so they have an easier time decoding the signal. DVI still needs to be decoded into the screen's native input signal.
– Kevin Panko
Sep 10 '14 at 4:52