An Adaptive Refresh Rate Conversion Method

Abstract

The present invention proposes an adaptive refresh rate conversion method, which classifies the refresh rates that may occur in an application into two categories: one is a stable refresh rate, which refers to a certain same frame rate that the processor continuously outputs within a period of time; the other is a transitional refresh rate, which refers to an intermediate refresh rate that appears briefly to connect different stable refresh rates. The refresh rate conversion is achieved by using a frame buffer, while minimizing the probability of consecutive frame drops and avoiding display stuttering caused by long-term consecutive frame drops.

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:

[0007] Step 1: Analyze the behavior of the image processor and classify the refresh rates that occur in the application into two categories: one is the stable refresh rate, which refers to a certain same frame rate that the processor continuously outputs within 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;

[0008] Step 2: With the output timing as a reference, delimit the cache write prohibition area. When a certain input frame appears within this area, resulting in a mismatch between the input and output frame rates, discard the frame;

[0009] Step 3: For the stable refresh rate, perform phase locking on the output frame and the input frame;

[0010] Step 4: For the transitional refresh rate, adjust the output frame rate.

[0011] Furthermore, in Step 3, assuming that there is an integer multiple or divisibility relationship between the input stable frame rate and the output fixed frame rate, the process of phase locking is as follows:

[0012] (1) When an input frame arrives, determine whether the input frame is the first input frame within the range of the current output frame. If it is, record the current output line number; if not, skip it;

[0013] (2) Calculate the difference between the output line numbers recorded twice in succession, and denote it as the phase difference;

[0014] (3) If the results of adjacent two phase differences are similar, it is considered that the input frame rate is stable; if the results of adjacent two phase differences are not similar, it is considered that the input frame rate is unstable;

[0015] (4) If the input frame rate is unstable, do not perform any processing and continue the next detection;

[0016] (5) If the input frame rate is stable, trigger a fine adjustment of the output frame rate, and superimpose the phase difference on the front porch before the field blanking to lock the phase;

[0017] (6) Continue the next detection.

[0018] Furthermore, in Step 4, the adjustment process is as follows:

[0019] (1) Monitor whether frame loss occurs;

[0020] (2) If frame loss occurs, determine whether two consecutive input frames are lost. If not, continue to monitor;

[0021] (3) If two consecutive frames are lost, trigger an adjustment of the output frame rate, and apply an increment to the front porch before the field blanking of the output frame to increase the phase difference between the input and output, so that the next input frame can be moved out of the write prohibition area;

[0022] (4) If the new input frame is already outside the prohibited writing area, immediately cancel the increment of the front porch of the vertical blanking interval and restore the original output refresh rate; if the new input frame is still within the prohibited writing area, maintain the current state until an input frame is outside the prohibited writing area;

[0023] (5) Continue to monitor.

[0024] The method only uses one-frame buffer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shown is a flowchart of the refresh rate conversion of the present invention.

[0026] Figure 2 Shown is a flowchart of the phase locking of the present invention.

[0027] Figure 3 Shown is a flowchart of the output frame rate adjustment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Please refer to Figures 1-3 , the present invention provides an adaptive refresh rate conversion method, including the following steps:

[0030] Step 1: Analyze the behavior of the image processor and classify the refresh rates that may occur in the application into two categories: one is the stable refresh rate, which refers to a certain same frame rate that the processor will continuously output within 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;

[0031] Step 2: Since there is only one-frame buffer, there is a possibility of screen image tearing when the input and output frame rates do not match. It is necessary to delimit a prohibited writing area for the buffer with reference to the output timing. When an input frame appears within this area, if the frame data is written into the buffer as usual, image tearing will surely occur. Therefore, at this time, only this frame can be discarded;

[0032] Step 3: For the stable refresh rate, because its duration is long, the input frame and the output frame need to be phase-locked so that the input frame data is not lost or lost evenly, reducing the visual impact on the display. Assume that there is an integer multiple or divisible relationship between the input stable frame rate and the output fixed frame rate. Then the process of phase locking is as follows:

[0033] 1. When an input frame arrives, determine whether the input frame is the first input frame within the current output frame range. If so, record the current output line number; if not, skip it.

[0034] 2. Calculate the difference between the output line numbers recorded twice in succession, hereinafter referred to as the phase difference.

[0035] 3. If two adjacent phase difference results are similar, it is considered that the input frame rate is stable.

[0036] 4. If the input frame rate is unstable, do not perform any processing and continue the next detection.

[0037] 5. If the input frame rate is stable, trigger the fine-tuning of the output frame rate, and superimpose the phase difference on the front porch before the field blanking to lock the phase.

[0038] 6. Continue the next detection.

[0039] Step 4: For the transition refresh rate, since the number of consecutive frames is also small, phase locking cannot be performed. However, since its occurrence position is relatively random, if it appears in the prohibited writing area, frame loss will occur. Single-frame loss has little impact on the display. If consecutive frame losses occur, it is necessary to trigger the adjustment of the output frame rate. The adjustment process is as follows:

[0040] 1. Monitor whether frame loss occurs.

[0041] 2. If frame loss occurs, determine whether two consecutive input frames are lost. If not, continue monitoring.

[0042] 3. If two consecutive frames are lost, trigger the adjustment of the output frame rate, and apply an increment to the front porch before the field blanking of the output frame to increase the phase difference between the input and the output, so that the next input frame can be moved out of the prohibited writing area as soon as possible.

[0043] 4. If the new input frame is already outside the prohibited writing area, immediately cancel the increment of the front porch before the field blanking and restore the original output refresh rate. If the new input frame is still within the prohibited writing area, maintain the current state until an input frame is outside the prohibited writing area.

[0044] 5. Continue monitoring.

[0045] Based on the above four points, it is possible to achieve smooth display at different stable refresh rates and reduce the number of lost frames at the transition refresh rate, thereby reducing the display stuttering phenomenon, on the premise of only using one-frame buffer, by means of adaptively dynamically fine-tuning the output frame rate.

[0046] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0047] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. 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 It includes the following steps: Step 1: Analyze the behavior of the image processor and classify the refresh rates that appear in the application into two categories: one is the stable refresh rate, which refers to a certain same frame rate that the processor will continuously output within 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: Taking the output timing as a reference, delimit the cache write - prohibited area. When a certain input frame appears within this area, causing a mismatch between the input and output frame rates, discard the frame; Step 3: For the stable refresh rate, perform phase - locking on the output frame and the input frame; Step 4: For the transitional refresh rate, adjust the output frame rate; In Step 3, assuming that there is an integer - multiple or divisible relationship between the input stable frame rate and the output fixed frame rate, the process of phase - locking is as follows: (1) When an input frame arrives, determine whether the input frame is the first input frame within the range of the current output frame. If it is, record the current output line number; if not, skip it; (2) Calculate the difference between the output line numbers recorded twice in succession, and denote it as the phase difference; (3) If the results of two adjacent phase differences are similar, it is considered that the input frame rate is stable; if the results of two adjacent phase differences are not similar, it is considered that the input frame rate is unstable; (4) If the input frame rate is unstable, do not perform any processing and continue the next detection; (5) If the input frame rate is stable, trigger a fine - tuning of the output frame rate, and superimpose the phase difference on the front porch before the field blanking to lock the phase; (6) Continue the next detection; 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 are lost. If not, continue to monitor; (3) If two consecutive frames are lost, trigger an adjustment of the output frame rate, and apply an increment to the front porch before 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 - prohibited area; (4) If the new input frame is already outside the write - prohibited area, immediately cancel the increment to the front porch before the field blanking and restore the original output refresh rate; if the new input frame is still within the write - prohibited area, maintain the current state until an input frame is outside the write - prohibited area; (5) Continue to monitor.

2. The adaptive refresh rate conversion method according to claim 1, wherein: The method only uses one - frame cache.

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