Linux（Ubutun）V4L2采集YUV422转YUV420，ALSA采集pcm、QT播放音频QOpenGL显示

在Ubutun16.0.中使用V4L2采集采集视频数据（YUV422）转换成YUV420数据，再使用ALSA采集pcm数据。
在两个线程中分别播放音频视频。
其中音频使用QT自带的multimedia播放
YUV420数据由Opengl实时渲染显示。

YUV422转420代码

//YUV422转YUV420
int YuvCapture::Yuv422ToYuv420(unsigned char *yuv422, unsigned char *yuv420, int width, int height)
{
    int ynum=width*height;
    int i,j,k=0;
    //得到Y分量
    for(i=0;i<ynum;i++){
        yuv420[i]=yuv422[i*2];
    }
    //得到U分量
    for(i=0;i<height;i++){
        if((i%2)!=0)continue;
        for(j=0;j<(width/2);j++){
            if((4*j+1)>(2*width))break;
            yuv420[ynum+k*2*width/4+j]=yuv422[i*2*width+4*j+1];
        }
        k++;
    }
    k=0;
    //得到V分量
    for(i=0;i<height;i++){
        if((i%2)==0)continue;
        for(j=0;j<(width/2);j++){
            if((4*j+3)>(2*width))break;
            yuv420[ynum+ynum/4+k*2*width/4+j]=yuv422[i*2*width+4*j+3];

        }
        k++;
    }

    return 1;
}

音频采集与视频采集在我的另外两篇博客中。

OpenGl渲染代码（使用QT中的OpenGLWidet）

#ifndef VIDEOPLAY_H
#define VIDEOPLAY_H
#include <QWidget>
#include <QOpenGLFunctions>
#include <QOpenGLWidget>
#include <QGLShaderProgram>
#include "ivideocall.h"
#include <mutex>

class VideoPlay : public QOpenGLWidget, protected QOpenGLFunctions, public IVideoCall
{
    Q_OBJECT
public:
    VideoPlay(QWidget *parent);
    ~VideoPlay();
    virtual void Init();
    virtual void Repaint(unsigned char *frame);
protected:
    void paintGL();
    void initializeGL();
    void resizeGL(int width, int height);
private:
    //shader程序
    QGLShaderProgram progma;

    //shader的yuv
    GLuint uint_yuv[3] = { 0 };
    //opengl中的材质地址
    GLuint opengl_texs[3] = { 0 };

    int width = 640;
    int height = 480;
    //材质内存空间
    unsigned char * datas[3] = { 0 };

    std::mutex mux;
};

#endif // VIDEOPLAY_H

CPP文件

#include "videoplay.h"
#include <QDebug>
#include <string.h>

VideoPlay::VideoPlay(QWidget *parent) :QOpenGLWidget(parent)
{}

VideoPlay::~VideoPlay()
{
    delete datas[0];
    delete datas[1];
    delete datas[2];
}
//自动加引号
#define GET_STR(x) #x
#define A_VER 3
#define T_VER 4

//顶点shader代码
const char *vString = GET_STR(
            attribute vec4 vertexIn;
        attribute vec2 textureIn;
varying vec2 textureOut;
void main(void)
{
    gl_Position = vertexIn;
    textureOut = textureIn;
}
);

//片元shader
const char *tString = GET_STR(
            varying vec2 textureOut;
        uniform sampler2D tex_y;
uniform sampler2D tex_u;
uniform sampler2D tex_v;
void main(void)
{
    vec3 yuv;
    vec3 rgb;
    yuv.x = texture2D(tex_y, textureOut).r;
    yuv.y = texture2D(tex_u, textureOut).r - 0.5;
    yuv.z = texture2D(tex_v, textureOut).r - 0.5;
    rgb = mat3(1.0, 1.0, 1.0,
               0.0, -0.39465, 2.03211,
               1.13983, -0.58060, 0.0) * yuv;
    gl_FragColor = vec4(rgb, 1.0);
}
);

void VideoPlay::Init()
{
    qDebug() << "Init done";
    mux.lock();
    this->width = 640;
    this->height = 480;

    //分配材质内存空间 Y U V
    datas[0] = new unsigned char[width * height];
    datas[1] = new unsigned char[width * height / 4];
    datas[2] = new unsigned char[width * height / 4];
    mux.unlock();
}

void VideoPlay::paintGL()
{
    mux.lock();
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, opengl_texs[0]);
    //修改材质内容
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, datas[0]);
    //关联shader
    glUniform1i(uint_yuv[0], 0);

    //1层
    glActiveTexture(GL_TEXTURE0 +1);
    glBindTexture(GL_TEXTURE_2D, opengl_texs[1]);
    //修改材质内容
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width/2, height/2, GL_RED, GL_UNSIGNED_BYTE, datas[1]);
    //关联shader
    glUniform1i(uint_yuv[1], 1);

    //2层
    glActiveTexture(GL_TEXTURE0 +2);
    glBindTexture(GL_TEXTURE_2D, opengl_texs[2]);
    //修改材质内容
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width/2, height/2, GL_RED, GL_UNSIGNED_BYTE, datas[2]);
    //关联shader
    glUniform1i(uint_yuv[2], 2);

    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    qDebug() << "Paint done";
    mux.unlock();
}

void VideoPlay::initializeGL()
{
    mux.lock();
    qDebug() << "initializeGL()";
    //初始化Opengl (QOFUNTIONs)函数
    initializeOpenGLFunctions();

    //program加载shadler脚本
    //顶点shader
    qDebug() << progma.addShaderFromSourceCode(QGLShader::Vertex, vString);
    //像素shader
    qDebug() << progma.addShaderFromSourceCode(QGLShader::Fragment, tString);

    //设置顶点坐标的变量
    progma.bindAttributeLocation("vertexIn", A_VER);

    //设置材质坐标
    progma.bindAttributeLocation("textureIn", T_VER);

    //编译shader
    qDebug() << "progma.link()" << progma.link();

    qDebug() << "progma.bind()" << progma.bind();

    //传入顶点材质坐标
    //顶点坐标
    static const GLfloat ver[] = {
        -1.0f, -1.0f,
        1.0f, -1.0f,
        -1.0f, 1.0f,
        1.0f, 1.0f
    };

    //材质坐标
    static const GLfloat tex[] = {
        0.0f, 1.0f,
        1.0f, 1.0f,
        0.0f, 0.0f,
        1.0f, 0.0f
    };

    //坐标写入到opengl中
    glVertexAttribPointer(A_VER, 2, GL_FLOAT, 0, 0, ver);
    glEnableVertexAttribArray(A_VER);

    glVertexAttribPointer(T_VER, 2, GL_FLOAT, 0, 0, tex);
    glEnableVertexAttribArray(T_VER);

    //从shader获取材质
    uint_yuv[0] = progma.uniformLocation("tex_y");
    uint_yuv[1] = progma.uniformLocation("tex_u");
    uint_yuv[2] = progma.uniformLocation("tex_v");

    //创建材质
    glGenTextures(3, opengl_texs);

    //Y
    glBindTexture(GL_TEXTURE_2D, opengl_texs[0]);
    //放大过滤线性插值
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    //缩小
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //创建材质空间
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

    //U
    glBindTexture(GL_TEXTURE_2D, opengl_texs[1]);
    //放大过滤线性插值
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    //缩小
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //创建材质空间
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width/2, height/2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

    //V
    glBindTexture(GL_TEXTURE_2D, opengl_texs[2]);
    //放大过滤线性插值
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    //缩小
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //创建材质空间
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width/2, height/2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

    mux.unlock();

}

void VideoPlay::Repaint(unsigned char *frame)
{
    mux.lock();
    if(!frame) return;
    int len  = width * height;
    memcpy(datas[0], frame, len);
    frame = frame + len;
    memcpy(datas[1], frame, (len / 4));
    frame  = frame + (len / 4);
    memcpy(datas[2], frame, (len / 4));
    mux.unlock();
    update();
}

void VideoPlay::resizeGL(int width, int height)
{
    qDebug() << "resizeGL:" << width << height;
}

最后效果 实时渲染视频播放音频

本代码仅供学习使用，代码没有做封装，退出时候还有BUG。
附上整个代码链接

链接：https://pan.baidu.com/s/1SqmKrhXUEZFwvqqwNUkGWQ 
提取码：cco3

编译需要安装alsa库，还有V4L库

需要FFMpeg资料可以私聊我。点个赞吧~~~