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Glenwing

Senior Moderator
  • Content Count

    16,390
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Reputation Activity

  1. Like
    Glenwing got a reaction from Bkstrat for a blog entry, ViewSonic XG2401 144 Hz over HDMI Testing   
    The ViewSonic XG2401 supports HDMI 1.4. I will now demonstrate it operating at 1920 × 1080 @ 144 Hz over HDMI. These tests are performed with an NVIDIA GeForce GTX 780 Ti, which also only supports up to HDMI 1.4.
    Display Settings Demonstration
    These settings show the XG2401 connected via HDMI on both ends at 1920 × 1080 @ 144 Hz with full RGB color. These settings are available out of the box without requiring any overclocking/custom resolutions. 1080p 144 Hz was in fact selected by default when the monitor was connected over HDMI for the first time, I didn't even need to set it to 144 Hz manually.
    Timing Parameters and EDID
    For 1920 × 1080 @ 144 Hz, ViewSonic has decided to define a set of custom timing parameters, with an effective resolution of 2026 × 1157 or a pixel rate of 337.0 Mpx/s, just barely within the 340 Mpx/s maximum of HDMI 1.4. Curiously, when connected via DisplayPort, the monitor uses slightly different parameters defined by the standardized CVT-R2 formula, 2000 × 1157 or 333.2 Mpx/s, which would also fall within the 340 Mpx/s limit of HDMI 1.4. However, these timings are not used for the HDMI connections for some reason.

    The EDID reports a maximum pixel clock of 340 Mpx/s, the highest allowed by HDMI 1.4. The 1080p 144 Hz format is defined within the CTA-861 extension block.

    The EDID is the same on both of the XG2401's HDMI ports, and 1080p 144 Hz works on both ports.
    Verification
    Of course, it is possible that the monitor is simply skipping frames, or failing to truly operate at 144 Hz in some other way. Some form of verification would be desirable.
    Verification by Oscilloscope
    This is measured using a Keysight EDUX1002A oscilloscope and a Texas Instruments TSL14S light-to-voltage converter. A pattern of alternating black and white frames was generated by the blurbusters flicker test (https://testufo.com/flicker). Since oscilloscopes are designed for measuring oscillating waveforms, a set of one white frame and one black frame is counted as a single "wave" (indicated by the two vertical orange lines marking the boundary of "one wave"). For this reason, the frequency displayed on the scope is half the actual refresh frequency, and the displayed period is twice the actual refresh period. In this case, 71.79 Hz indicates 71.79 sets of black-white transitions (2 frames) per second, for a total of 143.58 frames per second.
    Verification by High-Speed Camera
    This is a high-speed video of the blurbusters frame skipping test (https://testufo.com/frameskipping) shot with a Casio Exilim ZR100 at 1,000 FPS. Each frame of video represents 1 ms of real time. The video is played back at 30 FPS, meaning that every 1 second of video shows 30 ms of time. At 144 Hz, the display refreshes at intervals of 6.9444 ms. This means that we should see slightly more than 4 refreshes per second of video, which the video does show. This can also be verified more precisely by examining the video frame by frame and counting 7 frames between each refresh. We can also observe that the display is operating properly, without any frame skipping.
  2. Like
    Glenwing got a reaction from FPS god for a blog entry, ViewSonic XG2401 144 Hz over HDMI Testing   
    The ViewSonic XG2401 supports HDMI 1.4. I will now demonstrate it operating at 1920 × 1080 @ 144 Hz over HDMI. These tests are performed with an NVIDIA GeForce GTX 780 Ti, which also only supports up to HDMI 1.4.
    Display Settings Demonstration
    These settings show the XG2401 connected via HDMI on both ends at 1920 × 1080 @ 144 Hz with full RGB color. These settings are available out of the box without requiring any overclocking/custom resolutions. 1080p 144 Hz was in fact selected by default when the monitor was connected over HDMI for the first time, I didn't even need to set it to 144 Hz manually.
    Timing Parameters and EDID
    For 1920 × 1080 @ 144 Hz, ViewSonic has decided to define a set of custom timing parameters, with an effective resolution of 2026 × 1157 or a pixel rate of 337.0 Mpx/s, just barely within the 340 Mpx/s maximum of HDMI 1.4. Curiously, when connected via DisplayPort, the monitor uses slightly different parameters defined by the standardized CVT-R2 formula, 2000 × 1157 or 333.2 Mpx/s, which would also fall within the 340 Mpx/s limit of HDMI 1.4. However, these timings are not used for the HDMI connections for some reason.

    The EDID reports a maximum pixel clock of 340 Mpx/s, the highest allowed by HDMI 1.4. The 1080p 144 Hz format is defined within the CTA-861 extension block.

    The EDID is the same on both of the XG2401's HDMI ports, and 1080p 144 Hz works on both ports.
    Verification
    Of course, it is possible that the monitor is simply skipping frames, or failing to truly operate at 144 Hz in some other way. Some form of verification would be desirable.
    Verification by Oscilloscope
    This is measured using a Keysight EDUX1002A oscilloscope and a Texas Instruments TSL14S light-to-voltage converter. A pattern of alternating black and white frames was generated by the blurbusters flicker test (https://testufo.com/flicker). Since oscilloscopes are designed for measuring oscillating waveforms, a set of one white frame and one black frame is counted as a single "wave" (indicated by the two vertical orange lines marking the boundary of "one wave"). For this reason, the frequency displayed on the scope is half the actual refresh frequency, and the displayed period is twice the actual refresh period. In this case, 71.79 Hz indicates 71.79 sets of black-white transitions (2 frames) per second, for a total of 143.58 frames per second.
    Verification by High-Speed Camera
    This is a high-speed video of the blurbusters frame skipping test (https://testufo.com/frameskipping) shot with a Casio Exilim ZR100 at 1,000 FPS. Each frame of video represents 1 ms of real time. The video is played back at 30 FPS, meaning that every 1 second of video shows 30 ms of time. At 144 Hz, the display refreshes at intervals of 6.9444 ms. This means that we should see slightly more than 4 refreshes per second of video, which the video does show. This can also be verified more precisely by examining the video frame by frame and counting 7 frames between each refresh. We can also observe that the display is operating properly, without any frame skipping.
  3. Informative
    Glenwing got a reaction from Spotty for a blog entry, AOC G2460PF 120 Hz over HDMI Testing   
    The AOC G2460PF supports HDMI 1.4. I will now demonstrate it operating at 1920 × 1080 @ 120 Hz over HDMI. These tests are performed with an NVIDIA GeForce GTX 780 Ti, which also only supports HDMI 1.4.
     
    Display Settings Demonstration
    These settings show the G2460PF (EDID identifies itself as the "2460G4", Windows however does not read the name) connected via HDMI at 1920 × 1080 @ 120 Hz with full RGB color. A custom resolution was necessary to expose the 120 Hz option (CVT-RB timing was used, with a resulting pixel clock of 285 Mpx/s). Without custom resolutions, only options up to 60 Hz were available. Higher formats such as 144 Hz were also attempted, but failed. The monitor's HDMI port appears to support a maximum TMDS clock of approximately 300 MHz.
    Timing Parameters and EDID
    The EDID on this monitor reports a maximum of 170 Mpx/s, around the same as the maximum limit of SL-DVI or HDMI 1.2 (165 Mpx/s). However, in practice, the monitor's hardware works up to around 300 Mpx/s. Several custom resolutions were attempted. 1920 × 1080 @ 120 Hz worked with both CVT-RB timing (285 Mpx/s) and CTA-861 timing (297 Mpx/s), but anything above this point resulted in a black screen with a floating "Input Not Support" text. I attempted 1920 × 1080 @ 144 Hz at 317 Mpx/s without success, and even 138 Hz with a pixel rate of 304 Mpx/s (shown below) was rejected.

    This monitor makes a good demonstration for two important points:
    The maximum limit of an HDMI device can be any arbitrary limit that the manufacturer decides, or that the hardware is capable of. It is not simply "a device can support either HDMI 1.4 speed (340 Mpx/s) or be limited to HDMI 1.2 speed (165 Mpx/s)", or anything like that. The limitations can be anything, and may differ on every individual model. The limits listed in the EDID are simply values typed in by the manufacturer. The EDID does not have some method of magically detecting the actual hardware capabilities of the display. The EDID limits therefore do not necessarily represent the capabilities of the actual hardware. Verification
    Of course, it is possible that the monitor is simply skipping frames, or failing to truly operate at 144 Hz in some other way. Some form of verification would be desirable.
    Verification By Oscilloscope
    This is measured using a Keysight EDUX1002A oscilloscope and a Texas Instruments TSL14S light-to-voltage converter. A pattern of alternating black and white frames was generated by the blurbusters flicker test (https://testufo.com/flicker). Since oscilloscopes are designed for measuring oscillating waveforms, a set of one white frame and one black frame is counted as a single "wave" (indicated by the two vertical orange lines marking the boundary of "one wave"). For this reason, the frequency displayed on the scope is half the actual refresh frequency, and the displayed period is twice the actual refresh period. In this case, 60.00 Hz indicates 60 sets of black-white transitions (2 frames) per second, for a total of 120.00 frames per second. This demonstrates flawless 120 Hz operation.
    Verification By High-Speed Camera
    This is a high-speed video of the blurbusters frame skipping test (https://testufo.com/frameskipping) shot with a Casio Exilim ZR100 at 1,000 FPS. Each frame of video represents 1 ms of real time. The video is played back at 30 FPS, meaning that every 1 second of video shows 30 ms of time. At 120 Hz, the display refreshes at intervals of 8.333 ms. This means that we should see slightly fewer than 4 refreshes per second of video, which the video does show. This can also be verified more precisely by examining the video frame by frame and counting 8–9 frames between each refresh. We can also observe from this video that the display is operating properly, without any frame skipping.
    High-Speed Camera Complete Demonstration
    Just for good measure, this video shows the display operating at 1920 × 1080 @ 120 Hz over HDMI with the frame skipping test in a single take at 1,000 FPS.
  4. Informative
    Glenwing got a reaction from vanished for a blog entry, AOC G2460PF 120 Hz over HDMI Testing   
    The AOC G2460PF supports HDMI 1.4. I will now demonstrate it operating at 1920 × 1080 @ 120 Hz over HDMI. These tests are performed with an NVIDIA GeForce GTX 780 Ti, which also only supports HDMI 1.4.
     
    Display Settings Demonstration
    These settings show the G2460PF (EDID identifies itself as the "2460G4", Windows however does not read the name) connected via HDMI at 1920 × 1080 @ 120 Hz with full RGB color. A custom resolution was necessary to expose the 120 Hz option (CVT-RB timing was used, with a resulting pixel clock of 285 Mpx/s). Without custom resolutions, only options up to 60 Hz were available. Higher formats such as 144 Hz were also attempted, but failed. The monitor's HDMI port appears to support a maximum TMDS clock of approximately 300 MHz.
    Timing Parameters and EDID
    The EDID on this monitor reports a maximum of 170 Mpx/s, around the same as the maximum limit of SL-DVI or HDMI 1.2 (165 Mpx/s). However, in practice, the monitor's hardware works up to around 300 Mpx/s. Several custom resolutions were attempted. 1920 × 1080 @ 120 Hz worked with both CVT-RB timing (285 Mpx/s) and CTA-861 timing (297 Mpx/s), but anything above this point resulted in a black screen with a floating "Input Not Support" text. I attempted 1920 × 1080 @ 144 Hz at 317 Mpx/s without success, and even 138 Hz with a pixel rate of 304 Mpx/s (shown below) was rejected.

    This monitor makes a good demonstration for two important points:
    The maximum limit of an HDMI device can be any arbitrary limit that the manufacturer decides, or that the hardware is capable of. It is not simply "a device can support either HDMI 1.4 speed (340 Mpx/s) or be limited to HDMI 1.2 speed (165 Mpx/s)", or anything like that. The limitations can be anything, and may differ on every individual model. The limits listed in the EDID are simply values typed in by the manufacturer. The EDID does not have some method of magically detecting the actual hardware capabilities of the display. The EDID limits therefore do not necessarily represent the capabilities of the actual hardware. Verification
    Of course, it is possible that the monitor is simply skipping frames, or failing to truly operate at 144 Hz in some other way. Some form of verification would be desirable.
    Verification By Oscilloscope
    This is measured using a Keysight EDUX1002A oscilloscope and a Texas Instruments TSL14S light-to-voltage converter. A pattern of alternating black and white frames was generated by the blurbusters flicker test (https://testufo.com/flicker). Since oscilloscopes are designed for measuring oscillating waveforms, a set of one white frame and one black frame is counted as a single "wave" (indicated by the two vertical orange lines marking the boundary of "one wave"). For this reason, the frequency displayed on the scope is half the actual refresh frequency, and the displayed period is twice the actual refresh period. In this case, 60.00 Hz indicates 60 sets of black-white transitions (2 frames) per second, for a total of 120.00 frames per second. This demonstrates flawless 120 Hz operation.
    Verification By High-Speed Camera
    This is a high-speed video of the blurbusters frame skipping test (https://testufo.com/frameskipping) shot with a Casio Exilim ZR100 at 1,000 FPS. Each frame of video represents 1 ms of real time. The video is played back at 30 FPS, meaning that every 1 second of video shows 30 ms of time. At 120 Hz, the display refreshes at intervals of 8.333 ms. This means that we should see slightly fewer than 4 refreshes per second of video, which the video does show. This can also be verified more precisely by examining the video frame by frame and counting 8–9 frames between each refresh. We can also observe from this video that the display is operating properly, without any frame skipping.
    High-Speed Camera Complete Demonstration
    Just for good measure, this video shows the display operating at 1920 × 1080 @ 120 Hz over HDMI with the frame skipping test in a single take at 1,000 FPS.
  5. Funny
    Glenwing got a reaction from Daegun for a blog entry, How to Read the Product Description   
    "My laptop only has an HDMI port. I want to connect to the DisplayPort input on my monitor. Can I use this inexpensive DP to HDMI adapter I found on Amazon?"
     
    To answer this question, we must apply some reading skills:
     

     

     

     

     

     

     

     
     
    No, you can't.
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