Adaptive refresh rate conversion method

Abstract

The invention provides a self-adaptive refresh rate conversion method, which divides possible refresh rates in an application into two classes: one class is a stable refresh rate which refers to a certain same frame rate continuously output by a processor within a period of time; and the other type of refresh rate is a transition refresh rate which refers to an intermediate refresh rate which is used for connecting different stable refresh rates and appears briefly. The refresh rate conversion is realized by using a frame buffer, the probability of continuous frame loss is reduced as much as possible, and the display lagging caused by long-time continuous frame loss is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of display screen refresh, and in particular to an adaptive refresh rate conversion method. Background Art

[0002] With the advancement of display technology, current advanced display screens, such as (LTPO OLED), can already support a larger dynamic range of refresh rates (such as 120Hz~1Hz). In order to make full use of the characteristics of the screen to achieve high performance and low power consumption, the image processor has also been upgraded from fixed refresh rate output to variable refresh rate output, and the range of variation can cover the screen's support capabilities.

[0003] Usually, the image processor will dynamically adjust the refresh rate according to different application scenarios. For example, it will switch to high refresh rate mode (such as 120Hz) when playing games, switch to standard mode (such as 60Hz) when browsing documents, pictures, and web pages, switch to low refresh rate mode (such as 10Hz) when displaying static images, and further reduce the refresh rate (such as 1Hz) when the screen is in standby for a long time, thereby saving system power consumption. When this image processor that supports high dynamic range refresh rate is used with a screen that only supports standard refresh rate (such as 60Hz), refresh rate conversion is required.

[0004] Refresh rate conversion usually needs to be implemented with frame buffering. For the conversion from dynamic refresh rate to fixed refresh rate, due to the refresh rate mismatch, when the upstream refresh rate is high, frame loss will inevitably occur. For example, when 120Hz is converted to 60Hz, only one frame can be refreshed to the display for every two frames input, and the other frame is lost. Evenly spaced frame drops have little effect on the display, while continuous frame drops will cause obvious display stuttering and poor visual effects. One possible method is to use multi-frame buffering, where the number of cached frames depends on the ratio of the maximum output frame rate of the upstream image processor to the fixed refresh frequency of the downstream. The advantage of this method is that continuous frame drops and obvious display stuttering can be avoided to the greatest extent during the conversion process, but the problem is the resource overhead brought by multi-frame buffering, which will greatly increase the system cost and power consumption for system-on-chip applications.

[0005] In order to solve the above problems, the present invention designs an adaptive refresh rate conversion method, which is committed to using only one frame cache to achieve refresh rate conversion, while minimizing the probability of continuous frame loss and avoiding display freezes caused by long-term continuous frame loss. Summary of the invention

[0006] The present invention provides an adaptive refresh rate conversion method, comprising the following steps: Step 1: Analyze the behavior of the image processor and divide the refresh rates that appear in the application into two categories: one is the stable refresh rate, which refers to a certain frame rate that the processor will continuously output over a period of time; the other is the transitional refresh rate, which refers to the intermediate refresh rate that appears briefly to connect different stable refresh rates; Step 2: Using the output timing as a reference, define a cache write-forbidden area. When an input frame appears in this area, causing the input and output frame rates to mismatch, the frame is discarded. Step 3: For a stable refresh rate, phase lock the output frame with the input frame; Step 4: For the transition refresh rate, adjust the output frame rate.

[0007] Furthermore, in step 3, assuming that the input stable frame rate and the output fixed frame rate are integer multiples or divisible, the phase locking process is as follows: (1) When an input frame arrives, determine whether the input frame is the first input frame in the current output frame range. If so, record the current output line number; if not, skip it; (2) Calculate the difference in the number of output lines between two adjacent records, which is recorded as the phase difference; (3) If the two adjacent phase difference results are similar, the input frame rate is considered to be stable; if the two adjacent phase difference results are not similar, the input frame rate is considered to be unstable; (4) If the input frame rate is unstable, no processing is performed and the next detection is continued; (5) If the input frame rate is stable, the output frame rate is fine-tuned, and the phase difference is superimposed on the front shoulder of the field blanking to lock the phase; (6) Continue to the next test.

[0008] Furthermore, in step 4, the adjustment process is as follows: (1) Monitor whether frame loss occurs; (2) If frame loss occurs, determine whether two consecutive input frames have been lost. If not, continue monitoring; (3) If two consecutive frames are dropped, the output frame rate adjustment is triggered, and an increment is applied to the front porch of the field blanking of the output frame to increase the phase difference between the input and output so that the next input frame can move out of the write-inhibited area; (4) If the new input frame is already outside the prohibited writing area, the increment of the front shoulder of the field blanking is immediately canceled and the original output refresh rate is restored; if the new input frame is still in the prohibited writing area, the current state is maintained until an input frame is outside the prohibited writing area; (5) Continue monitoring.

[0009] The method described uses only one frame buffer. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Shown is a flow chart of the refresh rate conversion of the present invention.

[0011] Figure 2 Shown is a flow chart of the phase locking of the present invention.

[0012] Figure 3 Shown is a flow chart of output frame rate adjustment of the present invention. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] See also Figure 1-3 The present invention provides an adaptive refresh rate conversion method, comprising the following steps: Step 1: Analyze the behavior of the image processor and divide the possible refresh rates in the application into two categories: one is the stable refresh rate, which refers to the same frame rate that the processor will continuously output over a period of time; the other is the transitional refresh rate, which refers to the intermediate refresh rate that appears briefly to connect different stable refresh rates; Step 2: Since there is only one frame buffer, screen image tearing may occur when the input and output frame rates do not match. It is necessary to define a buffer write-forbidden area based on the output timing. When the input frame appears in this area, if the frame data is written into the buffer as usual, image tearing will inevitably occur. Therefore, the only option is to discard the frame. Step 3: For a stable refresh rate, since it lasts for a long time, the output frame and the input frame need to be able to phase lock so that the input frame data is not lost or lost evenly, reducing the visual impact on the display. Assuming that the input stable frame rate and the output fixed frame rate have an integer multiple or integer division relationship, the phase locking process is as follows: 1. When an input frame arrives, determine whether the input frame is the first input frame in the current output frame range. If so, record the current output line number; if not, skip it.

[0015] 2. Calculate the difference in the number of output lines between two adjacent records, hereinafter referred to as phase difference.

[0016] 3. If two adjacent phase difference results are close, the input frame rate is considered stable.

[0017] 4. If the input frame rate is unstable, no processing will be done and the next test will be continued.

[0018] 5. If the input frame rate is stable, the output frame rate is fine-tuned, and the phase difference is superimposed on the front shoulder of the vertical blanking to lock the phase.

[0019] 6. Continue to the next test.

[0020] Step 4: For the transition refresh rate, phase locking cannot be performed because the number of continuous frames is also small. However, since its position is relatively random, if it appears in the write-forbidden area, frame loss will occur. Single frame loss has little impact on the display. If frame loss occurs continuously, the output frame rate adjustment needs to be triggered. The adjustment process is as follows: 1. Monitor whether frame loss occurs.

[0021] 2. If frame loss occurs, determine whether two consecutive input frames are lost. If not, continue monitoring.

[0022] 3. If two consecutive frames are dropped, the output frame rate adjustment is triggered, and an increment is applied to the front porch of the field blanking of the output frame to increase the phase difference between the input and output, so that the next input frame moves out of the write-inhibited area as soon as possible.

[0023] 4. If the new input frame is already outside the forbidden write area, the increment of the front porch of the vertical blanking is immediately canceled to restore the original output refresh rate. If the new input frame is still in the forbidden write area, the current state is maintained until an input frame is outside the forbidden write area.

[0024] 5. Continue monitoring.

[0025] Combining the above four points, it is possible to achieve smooth display at different stable refresh rates by adaptively and dynamically fine-tuning the output frame rate under the premise of using only one frame cache, and reduce the number of dropped frames at transitional refresh rates to alleviate display stuttering.

[0026] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is limited by the appended claims and their equivalents.

Claims

1. An adaptive refresh rate conversion method, characterized in that: The following steps are involved: Step 1: Analyze the behavior of the image processor and divide the refresh rates that appear in the application into two categories: one is the stable refresh rate, which refers to a certain frame rate that the processor will continuously output over a period of time; the other is the transitional refresh rate, which refers to the intermediate refresh rate that appears briefly to connect different stable refresh rates; Step 2: Using the output timing as a reference, define a cache write-forbidden area. When an input frame appears in this area, causing the input and output frame rates to mismatch, the frame is discarded. Step 3: For a stable refresh rate, phase lock the output frame with the input frame; Step 4: For the transition refresh rate, adjust the output frame rate.

2. The adaptive refresh rate conversion method according to claim 1, characterized in that: In step 3, assuming that the input stable frame rate and the output fixed frame rate are integer multiples or divisible, the phase locking process is as follows: (1) When an input frame arrives, determine whether the input frame is the first input frame in the current output frame range. If so, record the current output line number; if not, skip it; (2) Calculate the difference in the number of output lines between two adjacent records, which is recorded as the phase difference; (3) If the two adjacent phase difference results are similar, the input frame rate is considered to be stable; if the two adjacent phase difference results are not similar, the input frame rate is considered to be unstable; (4) If the input frame rate is unstable, no processing is performed and the next detection is continued; (5) If the input frame rate is stable, the output frame rate is fine-tuned, and the phase difference is superimposed on the front shoulder of the field blanking to lock the phase; (6) Continue to the next test.

3. The adaptive refresh rate conversion method according to claim 2, characterized in that: In step 4, the adjustment process is as follows: (1) Monitor whether frame loss occurs; (2) If frame loss occurs, determine whether two consecutive input frames have been lost. If not, continue monitoring; (3) If two consecutive frames are dropped, the output frame rate adjustment is triggered, and an increment is applied to the front porch of the field blanking of the output frame to increase the phase difference between the input and output so that the next input frame can move out of the write-inhibited area; (4) If the new input frame is already outside the prohibited writing area, the increment of the front shoulder of the field blanking is immediately canceled and the original output refresh rate is restored; if the new input frame is still in the prohibited writing area, the current state is maintained until an input frame is outside the prohibited writing area; (5) Continue monitoring.

4. The adaptive refresh rate conversion method according to claim 3, characterized in that: The method described uses only one frame buffer.

Images