相机预览闪花屏条纹问题处理方法

和你一起终身学 习，这里是程序员Android
经典好文推荐，通过阅读本文，您将收获以下知识点:

一、问题描述

测试同事报了一个拍照后预览闪绿条纹问题

现象大概如下图：

image.png

二、问题分析

1. 复现问题 dump 图分析查看是哪个阶段导致的预览花屏问题

1.1 整个P2S I/O buffer 的 dump 方法

go 复制代码

adb root
adb remount
adb shell setenforce 0
adb shell setprop persist.vendor.mtk.camera.log_level 3
::P1 dump
::adb shell setprop vendor.debug.camera.dump.en 1
::adb shell setprop vendor.debug.feature.forceEnableIMGO 1
::adb shell setprop vendor.debug.camera.dump.p1.imgo 1

:: 预览魔法数字开启
adb shell setprop debug.cam.drawid 1
::enable img3o
adb shell setprop vendor.debug.fpipe.force.img3o 1
adb shell rm -rf /data/vendor/camera_dump/*
adb shell setprop vendor.debug.p2f.dump.enable 1
adb shell setprop vendor.debug.p2f.dump.mode 1
adb shell setprop vendor.debug.camera.preview.dump 1
::adb shell setprop vendor.debug.camera.preview.dump 0 复现问题后请关闭dump
adb shell pkill camera*
pause

1.2 camera_dump文件夹下的文件名称命令格式

UniqueKey-RequestNo-FrameNo-SensorDev-Port-BufferWidth-BufferHeight-BufferStride_ImageWidthxImageHeight_xxx.Format

在/data/vendor/camera_dump 下会dump 不同阶段的内容

image.png

sub P1 rrzo buffer

142407049-109-137-sub-rrzo-PW1280-PH960-BW2400__1280x960_10_3.packed_word
img3o buffer (P2Anode 下过了ISP 但是还没过MDP 的buffer，供3DNR用)

142407049-109-137-sub-img3o-PW1280-PH960-BW1280__1280x960_8_s0.yv12
sub 的P1 lcso buffer

142407049-109-137-sub-PW384-PH384-BW768__326x244_12_s0.lcso ---> sub sensor 的P1 lcso buffer
previewCallback ，也就是P2S 最终输出的sub sensor 的previewCallback buffer

142407049-109-137-sub-undef-PW960-PH720-BW960__960x720_8_s0.nv21
wdmao 代表判断为 display output buffer，也就是P2S 最终输出的sub sensor的display buffer

142407049-109-137-sub-wdmao-PW960-PH720-BW960__960x720_8_s0.nv21

通过 dump 查看经过P2Anode 输出的yv12 图就有条纹问题，然后需要查看有条纹问题那一帧附近的log。

1.3 dump 异常图Android log 分析

出现问题帧时间点： 14:25:21.430129 附近

image.png

1.4 查看14:25:21.430129 附件对应的 kernel log

go 复制代码

kernel log时间 +8 H +10ms 即kernel 时间 295 附近  = android 异常帧时间： 14:25:21.430129 
  异常条纹帧是，sensor driver 有调用set_max_framerate 更新 framelength =3008 导致预览坏帧发生。

go 复制代码

[  285.672406][T603753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     [  285.726555][T603753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
      // +8 H +10ms 即kernel 时间 295 附近  = android 异常帧时间： 14:25:21.430129
    [  285.823289][T500109] wdtk-5: [thread:109] 2025-03-10 06:25:11.875381 UTC;android time 2025-03-10 06:25:11.875381
     [  285.832074][ T3753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     [  285.876262][ T3753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     ... ...
     [  294.567745][T703753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     [  294.594359][T703753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     [  295.217019][T203753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     //+8 H +10ms 即kernel 时间 295 附近  = android 异常帧时间： 14:25:21.430129 
     // 异常条纹帧是，sensor driver 有调用set_max_framerate 更新 framelength =3008 导致预览坏帧发生
     [  295.268061][ T3753] 3AEventThd: xxx_SensroDriver[set_max_framerate] xxx_SensroDriver set_max_framerate():framerate = 300, min framelength should enable = 1
     [  295.269492][ T3753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3008,mini_framelegth=2506
     [  295.308503][T403753] 3AEventThd: xxx_SensroDriver[set_max_framerate] xxx_SensroDriver set_max_framerate():framerate = 240, min framelength should enable = 1
     [  295.309832][T403753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     [  295.341744][T403753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133
     [  295.396582][ T3753] 3AEventThd: xxx_SensroDriver[set_shutter] CST_004:xxx_SensroDriver set_shutter(): ratio = 64, real_shutter =6016, framelength =3133,mini_framelegth=3133

三、问题解决

发现Camera sensor驱动文件的流程存在少许问题，错误调节了framelength，导致预览出现概率性坏帧发生，找到问题点后，修改framelength update 流程，此问题后续压测不复现。

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