feat(render): VSync 呈现时钟升级为去抖 PI 滤波，消除周期性 hitch#56
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将 CalculatePresentTime 从"朴素首帧锚点 + 漂移硬重置"改为 alpha-beta(PI)时钟恢复 + 自适应 cushion + 迟到帧不拽网格： - offset 小比例项(Kp=1/64)跟踪偏移均值，保持呈现网格近似刚性 - skew 积分项(Ki=1/2048)消除主机/客户端时钟频差的斜坡滞后 - 在线抖动估计驱动自适应 cushion（净 LAN 低延迟、抖动网络更深缓冲） - 迟到帧按原网格时刻立即呈现，网格保持连续，消除旧硬重置的周期性 hitch 仅影响 VSync 模式(config.enableVsync=true)；低延迟模式走 OH_VideoDecoder_RenderOutputBuffer 直渲染，完全不受影响。 Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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📝 WalkthroughWalkthrough本次修改重构了 NativeRender 的 VSync 呈现时间计算逻辑，改为基于单调时钟的偏移、频差和抖动在线估计，并同步更新了相关状态字段；另外还更新了一个子模块指针。 Changes呈现时间估计模型重构
子模块指针更新
Estimated code review effort: 4 (Complex) | ~45 minutes 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Actionable comments posted: 2
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@nativelib/src/main/cpp/native_render.cpp`:
- Around line 327-330: The discontinuity check in native_render.cpp only treats
forward PTS jumps greater than 2 seconds as a reset, so smaller reconnect/seek
jumps still flow through the PI path and can skew targetPresentTimeNs. Update
the discontinuity logic in the render timing path around the PTS comparison in
native_render.cpp so that smaller forward jumps within the reconnect/seek range
also trigger a re-anchor based on frame interval or continuity threshold, while
still keeping 2 seconds as the maximum upper bound. Use the existing timing
state such as timeBaseInitialized_ and lastPtsUs_ to detect and reset continuity
before the PI limiter runs.
- Around line 353-357: The PI gain updates in native_render.cpp use bit shifts
on ec, which can bias negative values compared with the intended Kp/Ki behavior.
Update the estimatedOffsetNs_ and skewNs_ calculations in the native render
logic to use division by 64 and 2048 instead of right shifts, keeping the
existing ec clamp and the surrounding PI controller flow intact.
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
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📒 Files selected for processing (2)
nativelib/src/main/cpp/native_render.cppnativelib/src/main/cpp/native_render.h
| // 检测 PTS 不连续（重连 / seek / 编码器重启）：PTS 回退，或跳变 > 2s。 | ||
| const bool discontinuity = timeBaseInitialized_ && | ||
| (pts < lastPtsUs_ || (pts - lastPtsUs_) > 2000000LL); | ||
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🎯 Functional Correctness | 🟠 Major | ⚡ Quick win
补上 2 秒以内的 PTS 正向跳变重锚。
Line 329 只把 >2s 当作不连续；如果 reconnect/seek 让 PTS 正向跳 500ms～2s，会进入 PI 分支并被 ±8ms 限幅，targetPresentTimeNs 仍会偏到未来，可能造成 VSync 冻结。建议按帧间隔设置更近的连续性阈值，保留 2s 作为上限。
🐛 建议修正
- // 检测 PTS 不连续（重连 / seek / 编码器重启）：PTS 回退，或跳变 > 2s。
- const bool discontinuity = timeBaseInitialized_ &&
- (pts < lastPtsUs_ || (pts - lastPtsUs_) > 2000000LL);
+ // 检测 PTS 不连续（重连 / seek / 编码器重启）：PTS 回退，或明显超过正常帧间隔。
+ const int64_t ptsDeltaUs = pts - lastPtsUs_;
+ int64_t discontinuityThresholdUs = (frameIntervalNs / 1000LL) * 8;
+ if (discontinuityThresholdUs < 250000LL) discontinuityThresholdUs = 250000LL;
+ else if (discontinuityThresholdUs > 2000000LL) discontinuityThresholdUs = 2000000LL;
+ const bool discontinuity = timeBaseInitialized_ &&
+ (ptsDeltaUs < 0 || ptsDeltaUs > discontinuityThresholdUs);📝 Committable suggestion
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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| // 检测 PTS 不连续（重连 / seek / 编码器重启）：PTS 回退，或跳变 > 2s。 | |
| const bool discontinuity = timeBaseInitialized_ && | |
| (pts < lastPtsUs_ || (pts - lastPtsUs_) > 2000000LL); | |
| // 检测 PTS 不连续（重连 / seek / 编码器重启）：PTS 回退，或明显超过正常帧间隔。 | |
| const int64_t ptsDeltaUs = pts - lastPtsUs_; | |
| int64_t discontinuityThresholdUs = (frameIntervalNs / 1000LL) * 8; | |
| if (discontinuityThresholdUs < 250000LL) discontinuityThresholdUs = 250000LL; | |
| else if (discontinuityThresholdUs > 2000000LL) discontinuityThresholdUs = 2000000LL; | |
| const bool discontinuity = timeBaseInitialized_ && | |
| (ptsDeltaUs < 0 || ptsDeltaUs > discontinuityThresholdUs); |
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@nativelib/src/main/cpp/native_render.cpp` around lines 327 - 330, The
discontinuity check in native_render.cpp only treats forward PTS jumps greater
than 2 seconds as a reset, so smaller reconnect/seek jumps still flow through
the PI path and can skew targetPresentTimeNs. Update the discontinuity logic in
the render timing path around the PTS comparison in native_render.cpp so that
smaller forward jumps within the reconnect/seek range also trigger a re-anchor
based on frame interval or continuity threshold, while still keeping 2 seconds
as the maximum upper bound. Use the existing timing state such as
timeBaseInitialized_ and lastPtsUs_ to detect and reset continuity before the PI
limiter runs.
ec>>6 / ec>>11 为算术右移(向负无穷取整)，对负 ec 与预期的 ec/64、 ec/2048(向零取整)差 1 单位。稳态残差常处亚-2048ns 区间，右移每帧 多减 1 并累积进 skew 积分项——离线仿真显示会把 skew 估计带成错误负号。 改为整除后无此直流偏置，且与注释中 Kp=1/64、Ki=1/2048 语义一致。 Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
1 participant
背景
主机(Sunshine)把捕获时刻(QPC 精度)写进 RTP 90kHz 时间戳，common-c 在
RtpVideoQueue.c映射为presentationTimeUs（以首帧为原点的呈现时间）。鸿蒙端native_render一直用它做 host→本地时钟的呈现映射，但旧滤波器是"首帧锚点 + 漂移时硬重置"，会周期性产生可见 hitch。改动
CalculatePresentTime升级为 alpha-beta(PI)时钟恢复 + 自适应 cushion：受影响的帧节奏模式
config.enableVsync = true）RenderOutputBufferAtTime，本 PR 改的就是它的呈现时刻计算enableVsync = false）OH_VideoDecoder_RenderOutputBuffer直渲染，完全绕过CalculatePresentTime验证
因 OHOS NDK 全量构建需 DevEco 环境，采用离线仿真（g++，抽取函数原文逐字编译，
-Wall -Wextra零警告）对比新旧算法，4 场景（净 LAN / 典型 WiFi / 抖动远端 / 120fps）：风险
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