Feb 27, 2025 · DispSync is a software phase-lock loop (PLL) that generates the VSYNC and SF_VSYNC signals used by Choreographer and SurfaceFlinger, even if not offset from hardware VSYNC. Figure 1. DispSync flow. DispSync has the following qualities: Reference — HW_VSYNC_0. Output — VSYNC and SF_VSYNC.

Jan 15, 2015 · The DispSync code will instead use the timestamps from retire fences (which is a whole other discussion) to see if it is falling out of sync, and will temporarily re-enable the hardware signal until it's back on track.

Jun 8, 2021 · In general, you'll simply want a suspend function (or a suspending piece of code in this case) instead of a function that returns a Flow. Now, whether you keep your single-item flow or not, you can use the coroutineScope { ... } suspending function to define a local scope from which you can start coroutines.

Mar 13, 2020 · When the APP submits the generated interface to Buffer, it will call the operation of queueBuffer, and finally notify the SF composition interface. When SF needs to synthesize interface, it sends request Vsync signal to EventThread (SF),EventThread (SF) to DispSyncThread thread.

Jan 16, 2020 · This process is optimized by making the DispSync thread of SurfaceFlinger directly responsible for the propagation of periodic VSYNC signals to the other components of the display pipeline.

Aug 16, 2017 · The SurfaceFlinger DispSync * enhancements may cause the Choreographer-reported vsync time to be offset from the * actual-reported vsync time (which may itself be slightly offset from the actual-actual * vsync time).

Android is designed to use VSYNC at its core, but there are multiple VSYNC signals that it employs. Via https://source.android.com/devices/graphics/implement.html in the "VSYNC Offset" section, there is a flow diagram which diagrams three VSYNC signals: HW_VSYNC_0, VSYNC, and SF-VSYNC.

Nov 19, 2021 · 因此，为了解决延迟的问题，Android 系统引入了 软件 VSYNC 模型 DispSync. 承接上文，SurfaceFlinger 和 App 端都需要依据 VSYNC 来“行事”。 在引入软件 VSYNC 模型后，SurfaceFlinger 和 App 端将改为 依赖软件生成的 VSYNC 信号。 DispSync 接收来自硬件的 VSYNC 信号，然后在 指定的偏移（Phase） 之后分别发送软件 VSYNC 至 SurfaceFlinger 和 App。 为了方便区分，硬件 VYSNC 表示为 HW_VSYNC_0，发送至 SurfaceFlinger 以及 …

Jul 26, 2019 · DispSync 类似于一个 PLL（phase lock loop，锁相回路），它通过接收硬件 VSYNC，然后给其他关心硬件 VSYNC 的组件（SurfaceFlinger 和需要渲染的 app）在指定的偏移以后发送软件 VSYNC， 并且当误差在可接受的范围内，将会关闭硬件 VSYNC。 谷歌的 这篇文档 里面详细有一张非常准确的图： （为了方便，后面所有的 硬件 VSYNC 使用 HW-VSYNC 代指， 软件 VSYNC 使用 SW-VSYNC 代指） 前面提到 DispSync 是一个模拟 HW-VSYNC 的软件模 …

Nov 3, 2019 · DispSync 类似于一个 PLL（phase lock loop，锁相回路），它通过接收硬件 VSYNC，然后给其他关心硬件 VSYNC 的组件（SurfaceFlinger 和需要渲染的 app）在指定的偏移以后发送软件 VSYNC，**并且当误差在可接受的范围内，将会关闭硬件 VSYNC。 **谷歌的 这篇文档 里面详细有一张非常准确的图： （为了方便，后面所有的 硬件 VSYNC 使用 HW-VSYNC 代指， 软件 VSYNC 使用 SW-VSYNC 代指） 前面提到 DispSync 是一个模拟 HW-VSYNC 的 …