RK3568 重新封装V4l2为一个C++ Camera管理类 （基于RK编译环境，纯linux环境得小伙伴可以自己阅读代码做出对应得修改主要修改(CameraReader.cpp CameraReader,h thread.h))

CameraReader.cpp

/*
 * Copyright 2015 Rockchip Electronics Co. LTD
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define MODULE_TAG "CameraReader"



#include "mpp_log.h"
#include "mpp_mem.h"
#include "CameraReader.h"

CameraReader::CameraReader(const char *device, RK_U32 bufcnt, RK_U32 width, RK_U32 height, MppFrameFormat fmt)
:thread(device),
mBufcnt(bufcnt),
mWidth(width),
mHeight(height),
mFmt(fmt)
{
       strcpy(mDevice,device);
}

// Wrap ioctl() to spin on EINTR
RK_S32 CameraReader::Ioctl(RK_S32 fd, RK_S32 req, void* arg)
{
    struct timespec poll_time;
    RK_S32 ret;

    while ((ret = ioctl(fd, req, arg))) {
        if (ret == -1 && (EINTR != errno && EAGAIN != errno)) {
            // mpp_err("ret = %d, errno %d", ret, errno);
            break;
        }
        // 10 milliseconds
        poll_time.tv_sec = 0;
        poll_time.tv_nsec = 10000000;
        nanosleep(&poll_time, NULL);
    }

    return ret;
}

// Create a new context to capture frames from <fname>.
// Returns NULL on error.
RK_S32 CameraReader::Init(const char *device, RK_U32 bufcnt, RK_U32 width, RK_U32 height, MppFrameFormat format)
{
    struct v4l2_capability     cap;
    struct v4l2_format         vfmt;
    struct v4l2_requestbuffers req;
    struct v4l2_buffer         buf;
    enum   v4l2_buf_type       type;
    RK_U32 i;
    RK_U32 buf_len = 0;
   
    mCtx = mpp_calloc(CamSource, 1);
    if (!mCtx)
        return -1;

    mCtx->bufcnt = bufcnt;
    mCtx->fd = open(device, O_RDWR, 0);
    if (mCtx->fd < 0) {
        mpp_err_f("Cannot open device\n");
        goto FAIL;
    }

    // Determine if fd is a V4L2 Device
    if (0 != Ioctl(mCtx->fd, VIDIOC_QUERYCAP, &cap)) {
        mpp_err_f("Not v4l2 compatible\n");
        goto FAIL;
    }

    if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) && !(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE_MPLANE)) {
        mpp_err_f("Capture not supported\n");
        goto FAIL;
    }

    if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
        mpp_err_f("Streaming IO Not Supported\n");
        goto FAIL;
    }

    // Preserve original settings as set by v4l2-ctl for example
    vfmt = (struct v4l2_format) {0};
    vfmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    if (cap.capabilities & V4L2_CAP_VIDEO_CAPTURE_MPLANE)
        vfmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;

    vfmt.fmt.pix.width = width;
    vfmt.fmt.pix.height = height;

    if (MPP_FRAME_FMT_IS_YUV(format)) {
        vfmt.fmt.pix.pixelformat = V4L2_yuv_cfg[format - MPP_FRAME_FMT_YUV];
    } else if (MPP_FRAME_FMT_IS_RGB(format)) {
        vfmt.fmt.pix.pixelformat = V4L2_RGB_cfg[format - MPP_FRAME_FMT_RGB];
    }

    if (!vfmt.fmt.pix.pixelformat)
        vfmt.fmt.pix.pixelformat = V4L2_PIX_FMT_NV12;

    type = (v4l2_buf_type) vfmt.type;
    mCtx->type = (v4l2_buf_type) vfmt.type;

    if (-1 == Ioctl(mCtx->fd, VIDIOC_S_FMT, &vfmt)) {
        mpp_err_f("VIDIOC_S_FMT\n");
        goto FAIL;
    }

    if (-1 == Ioctl(mCtx->fd, VIDIOC_G_FMT, &vfmt)) {
        mpp_err_f("VIDIOC_G_FMT\n");
        goto FAIL;
    }

    mpp_log("get width %d height %d", vfmt.fmt.pix.width, vfmt.fmt.pix.height);

    // Request memory-mapped buffers
    req = (struct v4l2_requestbuffers) {0};
    req.count  = mCtx->bufcnt;
    req.type   = type;
    req.memory = V4L2_MEMORY_MMAP;
    if (-1 == Ioctl(mCtx->fd, VIDIOC_REQBUFS, &req)) {
        mpp_err_f("Device does not support mmap\n");
        goto FAIL;
    }

    if (req.count != mCtx->bufcnt) {
        mpp_err_f("Device buffer count mismatch\n");
        goto FAIL;
    }

    // mmap() the buffers into userspace memory
    for (i = 0 ; i < mCtx->bufcnt; i++) {
        buf = (struct v4l2_buffer) {0};
        buf.type    = type;
        buf.memory  = V4L2_MEMORY_MMAP;
        buf.index   = i;
        struct v4l2_plane planes[FMT_NUM_PLANES];
        buf.memory = V4L2_MEMORY_MMAP;
        if (V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE == type) {
            buf.m.planes = planes;
            buf.length = FMT_NUM_PLANES;
        }

        if (-1 == Ioctl(mCtx->fd, VIDIOC_QUERYBUF, &buf)) {
            mpp_err_f("ERROR: VIDIOC_QUERYBUF\n");
            goto FAIL;
        }

        mCtx->fbuf[i].start = mmap(NULL, buf.length,
                                  PROT_READ | PROT_WRITE, MAP_SHARED,
                                  mCtx->fd, buf.m.offset);
        if (V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE == buf.type) {
            // tmp_buffers[n_buffers].length = buf.m.planes[0].length;
            buf_len = buf.m.planes[0].length;
            mCtx->fbuf[i].start =
                mmap(NULL /* start anywhere */,
                     buf.m.planes[0].length,
                     PROT_READ | PROT_WRITE /* required */,
                     MAP_SHARED /* recommended */,
                     mCtx->fd, buf.m.planes[0].m.mem_offset);
        } else {
            buf_len = buf.length;
            mCtx->fbuf[i].start =
                mmap(NULL /* start anywhere */,
                     buf.length,
                     PROT_READ | PROT_WRITE /* required */,
                     MAP_SHARED /* recommended */,
                     mCtx->fd, buf.m.offset);
        }
        if (MAP_FAILED == mCtx->fbuf[i].start) {
            mpp_err_f("ERROR: Failed to map device frame buffers\n");
            goto FAIL;
        }
        struct v4l2_exportbuffer expbuf = (struct v4l2_exportbuffer) {0} ;
        // xcam_mem_clear (expbuf);
        expbuf.type = type;
        expbuf.index = i;
        expbuf.flags = O_CLOEXEC;
        if (Ioctl(mCtx->fd, VIDIOC_EXPBUF, &expbuf) < 0) {
            mpp_err_f("get dma buf failed\n");
            goto FAIL;
        } else {
            mpp_log("get dma buf(%d)-fd: %d\n", i, expbuf.fd);
            MppBufferInfo info;
            memset(&info, 0, sizeof(MppBufferInfo));
            info.type = MPP_BUFFER_TYPE_EXT_DMA;
            info.fd =  expbuf.fd;
            info.size = buf_len & 0x07ffffff;
            info.index = (buf_len & 0xf8000000) >> 27;
            mpp_buffer_import(&mCtx->fbuf[i].buffer, &info);
        }
        mCtx->fbuf[i].export_fd = expbuf.fd;
    }

    for (i = 0; i < mCtx->bufcnt; i++ ) {
        struct v4l2_plane planes[FMT_NUM_PLANES];

        buf = (struct v4l2_buffer) {0};
        buf.type    = type;
        buf.memory  = V4L2_MEMORY_MMAP;
        buf.index   = i;
        buf.memory = V4L2_MEMORY_MMAP;

        if (V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE == type) {
            buf.m.planes = planes;
            buf.length = FMT_NUM_PLANES;
        }

        if (-1 == Ioctl(mCtx->fd, VIDIOC_QBUF, &buf)) {
            mpp_err_f("ERROR: VIDIOC_QBUF %d\n", i);
            Deinit(mCtx);
            goto FAIL;
        }
    }

    // Start capturing
    if (-1 == Ioctl(mCtx->fd, VIDIOC_STREAMON, &type)) {
        mpp_err_f("ERROR: VIDIOC_STREAMON\n");
        Deinit(mCtx);
        goto FAIL;
    }

    //skip some frames at start
    for (i = 0; i < mCtx->bufcnt; i++ ) {
        RK_S32 idx = GetFrame(mCtx);
        if (idx >= 0)
            PutFrame(mCtx, idx);
    }
    code = new RkH264Encode();
    code->start();
    return MPP_OK;

FAIL:
    Deinit(mCtx);
    mCtx = NULL;
    return MPP_NOK;
}

// Free a context to capture frames from <fname>.
// Returns NULL on error.
MPP_RET CameraReader::Deinit(CamSource *ctx)
{
    struct v4l2_buffer buf;
    enum v4l2_buf_type type;
    RK_U32 i;

    if (NULL == ctx)
        return MPP_OK;

    if (ctx->fd < 0)
        return MPP_OK;

    // Stop capturing
    type = ctx->type;

    Ioctl(ctx->fd, VIDIOC_STREAMOFF, &type);

    // un-mmap() buffers
    for (i = 0 ; i < ctx->bufcnt; i++) {
        buf = (struct v4l2_buffer) {0};
        buf.type    = type;
        buf.memory  = V4L2_MEMORY_MMAP;
        buf.index   = i;
        Ioctl(ctx->fd, VIDIOC_QUERYBUF, &buf);
        if (ctx->fbuf[buf.index].buffer) {
            mpp_buffer_put(ctx->fbuf[buf.index].buffer);
        }
        munmap(ctx->fbuf[buf.index].start, buf.length);
    }

    // Close v4l2 device
    close(ctx->fd);
    MPP_FREE(ctx);
    return MPP_OK;
}

// Returns a pointer to a captured frame and its meta-data. NOT thread-safe.
RK_S32 CameraReader::GetFrame(CamSource *ctx)
{
    struct v4l2_buffer buf;
    enum v4l2_buf_type type;

    type = ctx->type;
    buf = (struct v4l2_buffer) {0};
    buf.type   = type;
    buf.memory = V4L2_MEMORY_MMAP;

    struct v4l2_plane planes[FMT_NUM_PLANES];
    if (V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE == type) {
        buf.m.planes = planes;
        buf.length = FMT_NUM_PLANES;
    }

    if (-1 == Ioctl(ctx->fd, VIDIOC_DQBUF, &buf)) {
        mpp_err_f("VIDIOC_DQBUF\n");
        return MPP_NOK;
    }

    if (buf.index > ctx->bufcnt) {
        mpp_err_f("buffer index out of bounds\n");
        return MPP_NOK;
    }

    if (V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE == type)
        buf.bytesused = buf.m.planes[0].bytesused;
  
    return buf.index;
}

// It's OK to capture into this framebuffer now
MPP_RET CameraReader::PutFrame(CamSource *ctx, RK_S32 idx)
{
    struct v4l2_buffer buf;
    enum v4l2_buf_type type;

    if (idx < 0)
        return MPP_OK;

    type = ctx->type;
    buf = (struct v4l2_buffer) {0};
    buf.type   = type;
    buf.memory = V4L2_MEMORY_MMAP;
    buf.index  = idx;

    struct v4l2_plane planes[FMT_NUM_PLANES];
    if (V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE == type) {
        buf.m.planes = planes;
        buf.length = FMT_NUM_PLANES;
    }

    // Tell kernel it's ok to overwrite this frame
    if (-1 == Ioctl(ctx->fd, VIDIOC_QBUF, &buf)) {
        mpp_err_f("VIDIOC_QBUF\n");
        return MPP_OK;
    }

    return MPP_OK;
}

MppBuffer CameraReader::Frame2Buf(CamSource *ctx, RK_S32 idx)
{
    if (idx < 0)
        return NULL;

    return ctx->fbuf[idx].buffer;
}
RK_S32 CameraReader::Open(){
    return Init(mDevice, mBufcnt,mWidth, mHeight, mFmt);
}

bool CameraReader::readyToRun(){
    return Open()==MPP_OK;
}
void CameraReader::start(){
    run();//线程开始跑
}
//线程主体函数
bool CameraReader::threadLoop(){
    //printf("threadLoop\n");
    static FILE *fp = NULL;
    static int count = 0;
    int index = GetFrame(mCtx);
   
    if(index == MPP_NOK){
        usleep(2000); 
        return true;
    }
    Frame2Buf(mCtx,index)//在这里出数据
     /×code->write();
     while(code->dealImageCompletes()){
      usleep(10); 
    }×/
    PutFrame(mCtx,index);
    return true;
}

CameraReader.h

/*
 * Copyright 2015 Rockchip Electronics Co. LTD
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef __CAMERA_READER_H__
#define __CAMERA_READER_H__
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <sys/select.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/videodev2.h>

#include "mpp_frame.h"
#include "thread.h"
#include "RkH264Encode.h"

typedef struct CamSource CamSource;
typedef struct CamFrame_t {
    void        *start;//ÍŒÏñÊýŸÝ¿ªÊŒ¶Î
    size_t      length;
    RK_S32      export_fd;
    RK_S32      sequence;
    MppBuffer   buffer;
} CamFrame;

struct CamSource {
    RK_S32              fd;     // Device handle
    RK_U32              bufcnt; // # of buffers
    enum v4l2_buf_type  type;
    MppFrameFormat      fmt;
    CamFrame            fbuf[10];// frame buffers
};

static RK_U32 V4L2_yuv_cfg[MPP_FMT_YUV_BUTT] = {
    V4L2_PIX_FMT_NV12,
    0,
    V4L2_PIX_FMT_NV16,
    0,
    V4L2_PIX_FMT_YVU420,
    V4L2_PIX_FMT_NV21,
    V4L2_PIX_FMT_YUV422P,
    V4L2_PIX_FMT_NV61,
    V4L2_PIX_FMT_YUYV,
    V4L2_PIX_FMT_YVYU,
    V4L2_PIX_FMT_UYVY,
    V4L2_PIX_FMT_VYUY,
    V4L2_PIX_FMT_GREY,
    0,
    0,
    0,
};

static RK_U32 V4L2_RGB_cfg[MPP_FMT_RGB_BUTT - MPP_FRAME_FMT_RGB] = {
    V4L2_PIX_FMT_RGB565,
    0,
    V4L2_PIX_FMT_RGB555,
    0,
    V4L2_PIX_FMT_RGB444,
    0,
    V4L2_PIX_FMT_RGB24,
    V4L2_PIX_FMT_BGR24,
    0,
    0,
    V4L2_PIX_FMT_RGB32,
    V4L2_PIX_FMT_BGR32,
    0,
    0,
};

#define FMT_NUM_PLANES 1

class CameraReader : public threadBase{
private:
    
    CamSource *mCtx = NULL;
    char mDevice[20];
    RK_U32 mBufcnt;
    RK_U32 mWidth;
    RK_U32 mHeight; 
    MppFrameFormat mFmt;
    RkH264Encode *code;

    // Create a new context to capture frames from <fname>. Returns NULL on error.
    RK_S32 Init(const char *device, RK_U32 bufcnt, RK_U32 width, RK_U32 height, MppFrameFormat fmt);
    RK_S32 Open();
    // Stop capturing and free a context.
    MPP_RET Deinit(CamSource *ctx);
    
    RK_S32 Ioctl(RK_S32 fd, RK_S32 req, void* arg);
    // Returns the next captured frame and its meta-data.
    RK_S32 GetFrame(CamSource *ctx);

    // Tells the kernel it's OK to overwrite a frame captured
    MPP_RET PutFrame(CamSource *ctx, RK_S32 idx);

    MppBuffer Frame2Buf(CamSource *ctx, RK_S32 idx);

    bool readyToRun();
    bool threadLoop();
public:
    CameraReader(const char *device, RK_U32 bufcnt, RK_U32 width, RK_U32 height, MppFrameFormat fmt);
    void start();
};
#endif /* __CAMERA_READER_H__ */

main_test

#include <string.h>
#include "rk_mpi.h"

#include "mpp_env.h"
#include "mpp_mem.h"
#include "mpp_time.h"
#include "mpp_debug.h"
#include "mpp_common.h"
#include "CameraReader.h"
int main(){
    CameraReader *camera1 = new CameraReader("/dev/video0", 10, 1920, 1080, MPP_FMT_YUV420SP);
    camera1->start();//线程开始
    while(1){
       usleep(33333);
    }
}

mpp/mpp-develop/test/CMakeLists.txt

....

# new dec multi unit test
add_mpp_test(mpi_dec_multi c)

#add
add_mpp_test(main cpp) 

...

mpp/mpp-develop/util/CMakeLists.txt

# vim: syntax=cmake
# ----------------------------------------------------------------------------
# add libvpu implement
# ----------------------------------------------------------------------------
include_directories(${PROJECT_SOURCE_DIR}/mpp/base/inc)

add_library(utils STATIC
    mpp_enc_roi_utils.c
    mpi_enc_utils.c
    mpi_dec_utils.c
    mpp_opt.c
    utils.c
    iniparser.c
    dictionary.c
    camera_source.c
	CameraReader.cpp
	thread.cpp
	thread.h
    )

target_link_libraries(utils mpp_base)

此类继承于threadBase在我上一片文章有linux下 C++ 封装一个简洁管理方便线程类_hmbbPdx_的博客-程序员宅基地