[RK3288][android7.1]修改USB摄像头预览像素分辨率

一，描述

1. 使用USB摄像头，一般情况下厂商提供的USB摄像头会有内置固件，里面支持多种分辨率（一般可直接插在电脑上看到拍照以及录像的质量），如下图所示：
   由上图可看出这款摄像头拍照支持的最大像素为1.9MP（大约200万像素），录像最大支持720P。
2. adb shell下也可以通过命令获取摄像头的信息：

rk3288:/ $ dumpsys media.camera
Camera module HAL API version: 0x1
Camera module API version: 0x1
Camera module name: RK29_ICS_CameraHal_Module
Camera module author: RockChip
Number of camera devices: 1
Number of normal camera devices: 1
Active Camera Clients:
[]
Allowed users:
0
Vendor tags left unimplemented.

Prior client events (most recent at top):
  01-01 10:56:49 : DISCONNECT device 0 client for package com.android.camera3 (PID 1959)
  01-01 10:56:35 : CONNECT device 0 client for package com.android.camera3 (PID 1959)
  01-01 09:22:11 : DISCONNECT device 0 client for package com.android.camera3 (PID 1462)
  01-01 09:21:33 : CONNECT device 0 client for package com.android.camera3 (PID 1462)
  01-01 08:00:59 : DISCONNECT device 0 client for package com.android.camera3 (PID 1462)
  01-01 08:00:46 : CONNECT device 0 client for package com.android.camera3 (PID 1462)
  01-01 08:00:17 : DISCONNECT device 0 client for package cameraserver (PID 234)
  01-01 08:00:15 : USER_SWITCH previous allowed users:  , current allowed users: 0

Camera 0 information:
  Facing: BACK
  Orientation: 0
  Resource Cost: 100
  Conflicting Devices: NONE
  Device version: 0x100
  Camera1 API shim is using parameters:
        CameraParameters::dump: mMap.size = 50
        antibanding: off
        antibanding-values: off,50hz,60hz,auto
        exposure-compensation: 0
        exposure-compensation-step: 1
        focal-length: 35
        focus-distances: 0.3,50,Infinity
        focus-mode: fixed
        focus-mode-values: fixed
        horizontal-view-angle: 10
        jpeg-quality: 70
        jpeg-thumbnail-height: 128
        jpeg-thumbnail-quality: 50
        jpeg-thumbnail-size-values: 0x0,160x128
        jpeg-thumbnail-width: 160
        max-exposure-compensation: 3
        max-num-detected-faces-hw: 2
        max-num-detected-faces-sw: 0
        max-num-focus-areas: 0
        max-num-metering-areas: 0
        max-zoom: 40
        min-exposure-compensation: -3
        picture-format: jpeg
        picture-format-values: jpeg
        picture-size: 1600x1200
        picture-size-values: 640x480,320x240,160x120,352x288,176x144,1280x1024,1600x1200
        preferred-preview-size-for-video:
        preview-format: yuv420sp
        preview-format-values: yuv420sp,yuv420p
        preview-fps-range: 5000,30000
        preview-fps-range-values: (5000,30000)
        preview-frame-rate: 30
        preview-frame-rate-values: 30,15,7
        preview-size: 640x480
        preview-size-values: 640x480,320x240,160x120,352x288,176x144,1280x1024,1600x1200
        recording-hint: false
        rk-continous-pic-num: 1
        rk-previwe-h-force: 0
        rk-previwe-w-force: 0
        rotation: 0
        vertical-view-angle: 10
        video-frame-format: yuv420sp
        video-size:
        video-size-values:
        video-snapshot-supported: true
        video-stabilization-supported: false
        whitebalance: auto
        whitebalance-values: auto,incandescent,fluorescent,daylight,cloudy-daylight
        zoom: 0
        zoom-ratios: 100,105,110,115,120,125,130,135,140,145,150,155,160,165,170,175,180,185,190,195,200,205,210,215,220,225,230,235,240,
245,250,255,260,265,270,275,280,285,290,295,300,
        zoom-supported: true
  Device 0 is closed, no client instance

No active camera clients yet.

Camera traces (0):
  No camera traces collected.

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二，问题现象

但是在Android系统上打开相机有时会发现拍照与录像预览时像素不清晰，分辨率并没有达到摄像头所支持的。通常情况下，预览分辨率是从设备 /data/camera/media_profiles.xml （ system/etc/media_profiles_default.xml）中配置的分辨率获取的。
可以修改对应的参数直接验证，方法如下：

adb root
adb remount
adb shell
busybox vi /data/camera/media_profiles.xml（编辑修改）
:wq（退出）
reboot

---

三，解决方法

如果需要在源码中（路径为/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp）指定，可以进行如下修改：

1. 拍照时，修改默认的PreviewSize预览分辨率和PictureSize照片大小，自行定制预览分辨率，把1600x1200设为最大分辨率。

diff --git a/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp b/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
index b565930a68..83a4888fa6 100755
--- a/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
+++ b/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
@@ -164,14 +164,14 @@ void CameraUSBAdapter::initDefaultParameters(int camFd)
     params.set(KEY_PREVIEW_W_FORCE,"0");
     params.set(KEY_PREVIEW_H_FORCE,"0");
-    params.set(CameraParameters::KEY_SUPPORTED_PREVIEW_SIZES, parameterString.string());
-    if(parameterString.contains("640x480"))
-        params.setPreviewSize(640,480);
+    params.set(CameraParameters::KEY_SUPPORTED_PREVIEW_SIZES, "640x480,320x240,160x120,352x288,176x144,1280x1024,1600x1200");
+    if(parameterString.contains("1600x1200"))//如果1600x1200有包含在支持分辨率KEY_SUPPORTED_PREVIEW_SIZES中为真,setPreviewSize为1600x1200;
+        params.setPreviewSize(1600,1200);
     else
         params.setPreviewSize(mCamDriverFrmWidthMax,mCamDriverFrmHeightMax);
     /*picture size setting*/      
-    params.set(CameraParameters::KEY_SUPPORTED_PICTURE_SIZES, parameterString.string());        
-    params.setPictureSize(mCamDriverFrmWidthMax,  mCamDriverFrmHeightMax);        
+    params.set(CameraParameters::KEY_SUPPORTED_PICTURE_SIZES, "640x480,320x240,160x120,352x288,176x144,1280x1024,1600x1200");
+    params.setPictureSize(1600,1200);
     
     /* set framerate */
     struct v4l2_streamparm setfps;

2. 录像时，设置默认的KEY_SUPPORTED_VIDEO_SIZES，把1600x1200设为最大预览分辨率。

KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO：设置在录制视频时首选的预览尺寸
KEY_VIDEO_SIZE：设置相机的视频尺寸
KEY_SUPPORTED_VIDEO_SIZES：获取相机支持的视频尺寸列表

diff --git a/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp b/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
index b565930a68..153d88407f 100755
--- a/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
+++ b/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
@@ -571,15 +571,15 @@ void CameraUSBAdapter::initDefaultParameters(int camFd)
#if (CONFIG_CAMERA_SETVIDEOSIZE == 0)
     if(false/*mIsCtsTest*/){
    
    
         if(gCamInfos[mCamId].facing_info.facing == CAMERA_FACING_BACK){
    
    
-             //back camera, may need to manually modify based on media_profiles.xml supported.
-             params.set(CameraParameters::KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO,"1920x1080");
-             params.set(CameraParameters::KEY_VIDEO_SIZE,"1920x1080");
-             params.set(CameraParameters::KEY_SUPPORTED_VIDEO_SIZES,"176x144,320x240,352x288,640x480,1280x720,1920x1080");
+             //back camera（后置）, may need to manually modify based on media_profiles.xml supported.
+             params.set(CameraParameters::KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO,"1600x1200");
+             params.set(CameraParameters::KEY_VIDEO_SIZE,"1600x1200");
+             params.set(CameraParameters::KEY_SUPPORTED_VIDEO_SIZES,"1600x1200");
         }else{
    
    
-             //front camera
-             params.set(CameraParameters::KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO,"640x480");
-             params.set(CameraParameters::KEY_VIDEO_SIZE,"640x480");
-             params.set(CameraParameters::KEY_SUPPORTED_VIDEO_SIZES,"176x144,320x240,352x288,640x480,1280x720");
+             //front camera（前置）
+             params.set(CameraParameters::KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO,"1600x1200");
+             params.set(CameraParameters::KEY_VIDEO_SIZE,"1600x1200");
+             params.set(CameraParameters::KEY_SUPPORTED_VIDEO_SIZES,"1600x1200");
         }
     } else {
    
    
          params.set(CameraParameters::KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO,"");

---

以上为设置为1600x1200预览分辨率的方法，想要更换其他分辨率，可以通过如上方法修改自己需要指定的分辨率；
注：一定要在USB摄像头支持的分辨率中指定自己需要的分辨率！