一，v4l2loopback 簡(jiǎn)介
v4l2loopback是一個(gè)Linux內(nèi)核模塊，它允許用戶創(chuàng)建虛擬視頻設(shè)備。這種虛擬視頻設(shè)備可以用于各種用途，例如將實(shí)際攝像頭的視頻流復(fù)制到虛擬設(shè)備上，或者用于視頻流的處理和分析等。v4l2loopback的主要作用是創(chuàng)建一個(gè)虛擬的Video4Linux2設(shè)備，它可以接收來(lái)自其他應(yīng)用程序的視頻數(shù)據(jù)，并將這些數(shù)據(jù)提供給其他應(yīng)用程序。
一旦加載了v4l2loopback模塊，就可以在/dev目錄下找到虛擬設(shè)備文件，通常命名為/dev/videoX（X是一個(gè)數(shù)字）。
二，驅(qū)動(dòng)文件配置
1. v4l2loopback 內(nèi)核模塊驅(qū)動(dòng)文件
1> v4l2loopback.c： v4l2loopback 內(nèi)核模塊的 C 語(yǔ)言源代碼文件。它包含了實(shí)現(xiàn) v4l2loopback 模塊功能的代碼。
2> v4l2loopback.h： v4l2loopback 內(nèi)核模塊的頭文件，通常包含一些宏定義、結(jié)構(gòu)體定義、函數(shù)聲明等。
3> v4l2loopback_formats.h：這個(gè)文件包含了有關(guān)視頻格式的定義和處理，用于支持 v4l2loopback 模塊對(duì)不同視頻格式的處理和轉(zhuǎn)換。
2. 移植 v4l2loopback驅(qū)動(dòng)
a. 將驅(qū)動(dòng)(v4l2loopback)拷貝到下面的文件夾：
./kernel/drivers/v4l2loopback
b. 在 Makefile 中添加 v4l2loopback設(shè)備
kernel/drivers/Makefile中添加：
+obj-y +=v4l2loopback/
c. 編譯kernel后會(huì)在目錄下生成對(duì)應(yīng)的.o文件
~/RK3568_Android11/kernel/drivers/v4l2loopback$ ls
built-in.a Makefile modules.builtin modules.order v4l2loopback.c v4l2loopback_formats.h v4l2loopback.h v4l2loopback.o
d. 驗(yàn)證 v4l2loopback.ko 模塊是否加載成功
設(shè)備 video9 就是 v4l2loopback.ko 模塊驅(qū)動(dòng)的設(shè)備,確認(rèn)v4l2loopback.ko 模塊移植成功。
三，hardware下整合v4l2loopback 虛擬攝像頭設(shè)備
源碼目錄：hardware/interfaces/camera/
修改補(bǔ)丁如下：
diff --git a/camera/device/3.4/default/ExternalCameraDevice.cpp b/camera/device/3.4/default/ExternalCameraDevice.cpp
index ec3264894..c2a1f4156 100755
--- a/camera/device/3.4/default/ExternalCameraDevice.cpp
+++ b/camera/device/3.4/default/ExternalCameraDevice.cpp
@@ -22,6 +22,8 @@
#include <array>
#include <regex>
#include <linux/videodev2.h>
+#include <linux/v4l2-subdev.h>
+#include <linux/videodev2.h>
#include "android-base/macros.h"
#include "CameraMetadata.h"
#include "../../3.2/default/include/convert.h"
@@ -373,6 +395,7 @@ status_t ExternalCameraDevice::initDefaultCharsKeys(
UPDATE(ANDROID_LENS_INFO_AVAILABLE_OPTICAL_STABILIZATION,
&opticalStabilizationMode, 1);
+ ALOGD("=========mCameraId.c_str():%s ANDROID_LENS_FACING_EXTERNAL:%d========", mCameraId.c_str(), ANDROID_LENS_FACING_EXTERNAL);
const uint8_t facing = ANDROID_LENS_FACING_EXTERNAL;
UPDATE(ANDROID_LENS_FACING, &facing, 1);
@@ -831,6 +854,16 @@ void ExternalCameraDevice::getFrameRateList(
}
}
+ struct v4l2_capability capability_v4l2;
+ int ret_query_v4l2 = ioctl(fd, VIDIOC_QUERYCAP, &capability_v4l2);
+ if (ret_query_v4l2 < 0) {
+ ALOGE("%s v4l2 QUERYCAP %s failed: %s", __FUNCTION__, strerror(errno));
+ }
+ if(strstr((const char*)capability_v4l2.driver,"v4l2")){
+ LOGD("======%s: capability_v4l2.driver:%s ========", __func__, capability_v4l2.driver);
+ SupportedV4L2Format::FrameRate fr = {1,30}; //特定幀率（1幀每秒到30幀每秒）添加到 format->frameRates 向量中
+ format->frameRates.push_back(fr);
+ }
if (format->frameRates.empty()) {
ALOGE("%s: failed to get supported frame rates for format:%c%c%c%c w %d h %d",
__FUNCTION__,
@@ -917,6 +950,12 @@ std::vector<SupportedV4L2Format> ExternalCameraDevice::getCandidateSupportedForm
int ret = 0;
while (ret == 0) {
ret = TEMP_FAILURE_RETRY(ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc));
+ if(ret < 0 && strstr((const char*)capability.driver, "v4l2")) {
+ ALOGE("driver.find :%s",capability.driver);
+ fmtdesc.pixelformat = V4L2_PIX_FMT_NV12;
+ ret = 0;
+ }
ALOGV("index:%d,ret:%d, format:%c%c%c%c", fmtdesc.index, ret,
fmtdesc.pixelformat & 0xFF,
(fmtdesc.pixelformat >> 8) & 0xFF,
@@ -963,6 +1002,39 @@ std::vector<SupportedV4L2Format> ExternalCameraDevice::getCandidateSupportedForm
}
}
}
+ if(strstr((const char*)capability.driver, "v4l2")) {
+ ALOGD("driver.find :%s",capability.driver);
+ SupportedV4L2Format format_1920x1080 {
+ .width = 1920,
+ .height = 1080,
+ .fourcc = V4L2_PIX_FMT_NV12
+ };
+ updateFpsBounds(fd, cropType, fpsLimits, format_1920x1080, outFmts);//名為 updateFpsBounds 的函數(shù)，向其傳遞了一些參數(shù)，包括文件描述符 fd、crop 類型、幀率限制、format_1920x1080 結(jié)構(gòu)和 outFmts
+ ret = -1;
+ }
}
fmtdesc.index++;
}
diff --git a/camera/device/3.4/default/ExternalCameraDeviceSession.cpp b/camera/device/3.4/default/ExternalCameraDeviceSession.cpp
index e2ab4fa2f..664d7d262 100644
--- a/camera/device/3.4/default/ExternalCameraDeviceSession.cpp
+++ b/camera/device/3.4/default/ExternalCameraDeviceSession.cpp
@@ -14,7 +14,7 @@
* limitations under the License.
*/
#define LOG_TAG "ExtCamDevSsn@3.4"
-//#define LOG_NDEBUG 0
+#define LOG_NDEBUG 0
#define ATRACE_TAG ATRACE_TAG_CAMERA
#include <log/log.h>
@@ -3104,7 +3104,18 @@ int ExternalCameraDeviceSession::configureV4l2StreamLocked(
ALOGE("%s: QUERYBUF %d failed: %s", __FUNCTION__, i, strerror(errno));
return -errno;
}
+//fy
+ ALOGD("==========mV4L2Buffer[%d] = (char*)mmap()==========", i);
+ if (buffer.memory == V4L2_MEMORY_MMAP) {
+ mV4L2Buffer[i] = (char*)mmap(0 /* start anywhere */ ,
+ buffer.length, PROT_READ, MAP_SHARED, mV4l2Fd.get(),
+ buffer.m.offset);
+ if (mV4L2Buffer[i] == MAP_FAILED) {
+ LOGE("%s(%d): Unable to map buffer(length:0x%x offset:0x%x) %s(err:%d)\n",__FUNCTION__,__LINE__, buffer.length,buffer.m.offset,strerror(errno),errno);
+ }
+ }
+ V4l2BufferLen = buffer.length;
if (TEMP_FAILURE_RETRY(ioctl(mV4l2Fd.get(), VIDIOC_QBUF, &buffer)) < 0) {
ALOGE("%s: QBUF %d failed: %s", __FUNCTION__, i, strerror(errno));
return -errno;
@@ -3401,8 +3412,10 @@ Status ExternalCameraDeviceSession::configureStreams(
}
}
// Find the smallest format that matches the desired aspect ratio and is wide/high enough
- SupportedV4L2Format v4l2Fmt {.width = 0, .height = 0};
- SupportedV4L2Format v4l2Fmt_tmp {.width = 0, .height = 0};
+// SupportedV4L2Format v4l2Fmt {.width = 0, .height = 0};
+// SupportedV4L2Format v4l2Fmt_tmp {.width = 0, .height = 0};
+//初始化寬度為 1920，高度為 1088，fourcc 值為 V4L2_PIX_FMT_NV12;
+ SupportedV4L2Format v4l2Fmt {.width = 1920, .height = 1088, .fourcc = V4L2_PIX_FMT_NV12};
+ SupportedV4L2Format v4l2Fmt_tmp {.width = 1920, .height = 1088, .fourcc = V4L2_PIX_FMT_NV12};
for (const auto& fmt : mSupportedFormats) {
uint32_t dim = (mCroppingType == VERTICAL) ? fmt.width : fmt.height;
if (dim >= maxDim) {
diff --git a/camera/device/3.4/default/include/ext_device_v3_4_impl/ExternalCameraDeviceSession_3.4.h b/camera/device/3.4/default/include/ext_device_v3_4_impl/ExternalCameraDeviceSession_3.4.h
index 209c5e91e..027a27ae7 100755
--- a/camera/device/3.4/default/include/ext_device_v3_4_impl/ExternalCameraDeviceSession_3.4.h
+++ b/camera/device/3.4/default/include/ext_device_v3_4_impl/ExternalCameraDeviceSession_3.4.h
@@ -383,6 +383,9 @@ protected:
SupportedV4L2Format mV4l2StreamingFmt;
double mV4l2StreamingFps = 0.0;
size_t mV4L2BufferCount = 0;
+ #define V4L2_BUFFER_MAX 32
+ char *mV4L2Buffer[V4L2_BUFFER_MAX];
+ unsigned int V4l2BufferLen = 0;
struct v4l2_plane planes[1];
struct v4l2_capability mCapability;
diff --git a/camera/device/3.4/default/include/ext_device_v3_4_impl/ExternalCameraDevice_3_4.h b/camera/device/3.4/default/include/ext_device_v3_4_impl/ExternalCameraDevice_3_4.h
index 6e0e4ebab..e085682d4 100644
diff --git a/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp b/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp
index 65447421c..a5a74e380 100755
--- a/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp
+++ b/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp
@@ -257,6 +257,8 @@ void ExternalCameraProviderImpl_2_4::addExternalCamera(const char* devName) {
}
void ExternalCameraProviderImpl_2_4::deviceAdded(const char* devName) {
+ ALOGD("=============%s===========", __func__);
+ struct v4l2_capability capability;
if (std::atoi(devName + kDevicePrefixLen) >= 30)
{
sp<device::V3_4::implementation::ExternalFakeCameraDevice> deviceImpl =
@@ -267,14 +269,15 @@ void ExternalCameraProviderImpl_2_4::deviceAdded(const char* devName) {
}
deviceImpl.clear();
} else {
- {
+ {
+ ALOGD("======fd(::open(devName, O_RDWR)) devName:%s ==========", devName);
base::unique_fd fd(::open(devName, O_RDWR));
if (fd.get() < 0) {
ALOGE("%s open v4l2 device %s failed:%s", __FUNCTION__, devName, strerror(errno));
return;
}
- struct v4l2_capability capability;
+// struct v4l2_capability capability;
int ret = ioctl(fd.get(), VIDIOC_QUERYCAP, &capability);
if (ret < 0) {
ALOGE("%s v4l2 QUERYCAP %s failed", __FUNCTION__, devName);
@@ -289,6 +292,7 @@ void ExternalCameraProviderImpl_2_4::deviceAdded(const char* devName) {
// See if we can initialize ExternalCameraDevice correctly
sp<device::V3_4::implementation::ExternalCameraDevice> deviceImpl =
new device::V3_4::implementation::ExternalCameraDevice(devName, mCfg);
+ ALOGD("=========ExternalCameraDevice(devName:%s======", devName);
if (deviceImpl == nullptr || deviceImpl->isInitFailed()) {
ALOGW("%s: Attempt to init camera device %s failed!", __FUNCTION__, devName);
return;
@@ -296,7 +300,15 @@ void ExternalCameraProviderImpl_2_4::deviceAdded(const char* devName) {
deviceImpl.clear();
}
- addExternalCamera(devName);
+ //fy
+ if(capability.device_caps & V4L2_CAP_VIDEO_CAPTURE) {
+ ALOGD("===========dzp_test: devName:%s========", devName);
+ addExternalCamera(devName);
+ }
+ else addExternalCamera(devName);
return;
}
@@ -331,6 +349,7 @@ ExternalCameraProviderImpl_2_4::HotplugThread::HotplugThread(
ExternalCameraProviderImpl_2_4::HotplugThread::~HotplugThread() {}
bool ExternalCameraProviderImpl_2_4::HotplugThread::threadLoop() {
+ ALOGD("============%s kDevicePath:%s========", __func__, kDevicePath);
// Find existing /dev/video* devices
DIR* devdir = opendir(kDevicePath);
if(devdir == 0) {
@@ -351,6 +370,7 @@ bool ExternalCameraProviderImpl_2_4::HotplugThread::threadLoop() {
snprintf(v4l2DevicePath, kMaxDevicePathLen,
"%s%s", kDevicePath, de->d_name);
mParent->deviceAdded(v4l2DevicePath);
+ ALOGD("=============v4l2DevicePath:%s ==============", v4l2DevicePath);
}
}
}
-
添加虛擬攝像頭設(shè)備接口：在 “hardware/interfaces/camera/” 目錄下可能會(huì)添加或修改相機(jī)設(shè)備的接口，以便 Android 系統(tǒng)可以與 v4l2loopback 虛擬攝像頭進(jìn)行交互。
-
實(shí)現(xiàn)虛擬攝像頭設(shè)備功能：可能會(huì)在該目錄下實(shí)現(xiàn)虛擬攝像頭設(shè)備的功能，包括與 Android 相機(jī)框架的集成、數(shù)據(jù)流處理等。
-
支持虛擬攝像頭的配置：可能會(huì)對(duì) Android 相機(jī)服務(wù)的配置進(jìn)行修改，以支持虛擬攝像頭設(shè)備的添加和管理。
改動(dòng)的目的是將 v4l2loopback 虛擬攝像頭設(shè)備整合到 Android 系統(tǒng)中，以便應(yīng)用程序可以與虛擬攝像頭進(jìn)行交互，并利用其提供的視頻流數(shù)據(jù)。文章來(lái)源：http://www.zghlxwxcb.cn/news/detail-805121.html
四，賦予虛擬攝像頭注冊(cè)節(jié)點(diǎn)權(quán)限
device/rockchip/common/ueventd.rockchip.rc中修改：
/dev/video9 0666 media camera
虛擬攝像頭注冊(cè)節(jié)點(diǎn)設(shè)為666權(quán)限是為了確保所有用戶都能夠訪問(wèn)和使用該節(jié)點(diǎn)。權(quán)限數(shù)字666表示所有用戶都有讀寫權(quán)限，這意味著任何用戶都可以讀取和寫入該節(jié)點(diǎn)，從而能夠?qū)μ摂M攝像頭進(jìn)行訪問(wèn)和控制。
例如，如果虛擬攝像頭用于視頻會(huì)議應(yīng)用程序，那么所有參與會(huì)議的用戶都需要能夠訪問(wèn)虛擬攝像頭節(jié)點(diǎn)。
需要注意的是，賦予666權(quán)限也可能存在一定的安全風(fēng)險(xiǎn)，因?yàn)檫@樣做會(huì)允許任何用戶都能夠?qū)υ摴?jié)點(diǎn)進(jìn)行讀寫操作。因此，在實(shí)際應(yīng)用中，需要仔細(xì)考慮安全性和訪問(wèn)控制的需求，以確定是否真的需要將虛擬攝像頭節(jié)點(diǎn)權(quán)限設(shè)置為666。文章來(lái)源地址http://www.zghlxwxcb.cn/news/detail-805121.html
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