音视频基础——libyuv格式转换

http://blog.csdn.net/fengbingchun/article/details/50323273

libyuv是Google开源的实现各种YUV与RGB之间相互转换、旋转、缩放的库。它是跨平台的，可在Windows、Linux、Mac、Android等操作系统，x86、x64、arm架构上进行编译运行，支持SSE、AVX、NEON等SIMD指令加速。

下面说一下libyuv在Windows7VS2013 x64上的编译步骤及使用：

1. 从https://code.google.com/p/libyuv/source/checkout或者https://github.com/lemenkov/libyuv下载libyuv源码；我是通过svn直接从google下载的，版本号是1433，更新日期2015年6月13日；

2. 通过cmake gui生成vs2013 x64工程，不需要额外的配置；

3. 打开Project.sln工程，重新编译，即可生成yuv.lib静态库；

4. 新添加一个test_libyuv控制台工程，用于测试yuv.lib的正确性，测试代码如下：

[cpp] view plaincopy

#include <iostream>
#include <assert.h>
#include "libyuv.h"
#include <cmath>
#include <opencv2/opencv.hpp>
void test_BGRAToI420(const cv::Mat& matSrc, int width, int height, int size_frame, cv::Mat& matDst);
void test_BGRAToNV21(const cv::Mat& matSrc, int width, int height, int size_frame, cv::Mat& matDst);
void test_BGRAToNV12(const cv::Mat& matSrc, int width, int height, int size_frame, cv::Mat& matDst);
int main(int argc, char* argv[])
{
cv::Mat matSrc = cv::imread("cat.jpg");
if (!matSrc.data) {
std::cout << "read src image error" << std::endl;
return -1;
}
//cv::resize(matSrc, matSrc, cv::Size(500, 111));
int width = matSrc.cols;
int height = matSrc.rows;
int size_frame = width * height;
cv::Mat matI420, matNV21, matNV12;
test_BGRAToI420(matSrc, width, height, size_frame, matI420);
test_BGRAToNV21(matSrc, width, height, size_frame, matNV21);
test_BGRAToNV12(matSrc, width, height, size_frame, matNV12);
assert((matI420.depth() == matNV21.depth()) && (matI420.depth() == matNV12.depth()));
assert((matI420.channels() == matNV21.channels()) && (matI420.channels() == matNV12.channels()));
for (int i = 0; i < height; i++) {
const unsigned char* pI420 = matI420.ptr(i);
const unsigned char* pNV21 = matNV21.ptr(i);
const unsigned char* pNV12 = matNV12.ptr(i);
for (int j = 0, m = 0; j < width; j++, m+=4) {
if ((pI420[m] != pNV21[m]) || (pI420[m] != pNV12[m]) ||
(pI420[m + 1] != pNV21[m + 1]) || (pI420[m + 1] != pNV12[m + 1]) ||
(pI420[m + 2] != pNV21[m + 2]) || (pI420[m + 2] != pNV12[m + 2]) ||
(pI420[m + 3] != pNV21[m + 3]) || (pI420[m + 3] != pNV12[m + 3])) {
std::cout << "convert error" << std::endl;
}
}
}
std::cout << "ok" << std::endl;
return 0;
}
void test_BGRAToI420(const cv::Mat& matSrc, int width, int height, int size_frame, cv::Mat& matDst)
{
// BGRA <--> I420(YUV420P)
cv::Mat matBGRA, matI420, matARGB;
cv::cvtColor(matSrc, matBGRA, cv::COLOR_BGR2BGRA);
matARGB = cv::Mat(height, width, CV_8UC4, cv::Scalar::all(0));
libyuv::BGRAToARGB(matBGRA.data, width * 4, matARGB.data, width * 4, width, height);
uchar* pI420 = new uchar[width * height + (width + 1) / 2 * (height + 1) / 2 * 2];
memset(pI420, 0, sizeof(uchar) * (width * height + (width + 1) / 2 * (height + 1) / 2 * 2));
uchar* dst_y = pI420;
int dst_y_stride = width;
uchar* dst_u = pI420 + size_frame;
int dst_u_stride = (width + 1) / 2;
uchar* dst_v = pI420 + size_frame + dst_u_stride * (height + 1) / 2;
int dst_v_stride = (width + 1) / 2;
libyuv::BGRAToI420(matARGB.data, width * 4, dst_y, dst_y_stride, dst_u, dst_u_stride, dst_v, dst_v_stride, width, height);
matI420 = cv::Mat(height, width, CV_8UC4, cv::Scalar::all(0));
libyuv::I420ToBGRA(dst_y, dst_y_stride, dst_u, dst_u_stride, dst_v, dst_v_stride, matI420.data, width * 4, width, height);
cv::Mat matBGRA_ = cv::Mat(height, width, CV_8UC4, cv::Scalar::all(0));
libyuv::ARGBToBGRA(matI420.data, width * 4, matBGRA_.data, width * 4, width, height);
cv::imwrite("I420_bgra.jpg", matBGRA_);
matBGRA_.copyTo(matDst);
int count_diff = 0;
int max_diff = 0;
int threshold = 20;//
for (int i = 0; i < height; i++) {
uchar* pSrc = matBGRA.ptr(i);
uchar* pDst = matBGRA_.ptr(i);
for (int j = 0, m = 0; j < width; j++, m += 4) {
int tmp = std::max(abs(pSrc[m] - pDst[m]), abs(pSrc[m + 1] - pDst[m + 1]));
tmp = std::max(tmp, abs(pSrc[m + 2] - pDst[m + 2]));
if (tmp > max_diff)
max_diff = tmp;
if (abs(pSrc[m] - pDst[m]) > threshold ||
abs(pSrc[m + 1] - pDst[m + 1]) > threshold ||
abs(pSrc[m + 2] - pDst[m + 2]) > threshold) {
count_diff++;
//std::cout << i << " " << j << std::endl;
}
}
}
std::cout << "convert I420 to BGRA diff max: " << max_diff << std::endl;
if (count_diff > width + height) {//
std::cout << "convert I420 to BGRA error." << std::endl;
std::cout << "diff num: " << count_diff << std::endl;
}
delete[] pI420;
}
void test_BGRAToNV12(const cv::Mat& matSrc, int width, int height, int size_frame, cv::Mat& matDst)
{
// BGRA <--> NV12
cv::Mat matBGRA, matNV12;
cv::cvtColor(matSrc, matBGRA, cv::COLOR_BGR2BGRA);
uchar* pNV12 = new uchar[width * height + ((width + 1) / 2) * ((height + 1) / 2) * 2];
memset(pNV12, 0, sizeof(uchar) * (width * height + ((width + 1) / 2) * ((height + 1) / 2) * 2));
uchar* dst_y = pNV12;
int dst_y_stride = width;
uchar* dst_vu = pNV12 + size_frame;
int dst_vu_stride = (width + 1) / 2 * 2;
libyuv::ARGBToNV12(matBGRA.data, width * 4, dst_y, dst_y_stride, dst_vu, dst_vu_stride, width, height);
matNV12 = cv::Mat(height, width, CV_8UC4, cv::Scalar::all(0));
libyuv::NV12ToARGB(dst_y, dst_y_stride, dst_vu, dst_vu_stride, matNV12.data, width * 4, width, height);
cv::imwrite("NV12_bgra.jpg", matNV12);
matNV12.copyTo(matDst);
int count_diff = 0;
int max_diff = 0;
int threshold = 20;//
for (int i = 0; i < height; i++) {
uchar* pSrc = matBGRA.ptr(i);
uchar* pDst = matNV12.ptr(i);
for (int j = 0, m = 0; j < width; j++, m += 4) {
int tmp = std::max(abs(pSrc[m] - pDst[m]), abs(pSrc[m + 1] - pDst[m + 1]));
tmp = std::max(tmp, abs(pSrc[m + 2] - pDst[m + 2]));
if (tmp > max_diff)
max_diff = tmp;
if (abs(pSrc[m] - pDst[m]) > threshold ||
abs(pSrc[m + 1] - pDst[m + 1]) > threshold ||
abs(pSrc[m + 2] - pDst[m + 2]) > threshold) {
count_diff++;
//std::cout << i << " " << j << std::endl;
}
}
}
std::cout << "convert NV12 to BGRA diff max: " << max_diff << std::endl;
if (count_diff > width + height) {//
std::cout << "convert NV12 to BGRA error." << std::endl;
std::cout << "diff num: " << count_diff << std::endl;
}
delete[] pNV12;
}
void test_BGRAToNV21(const cv::Mat& matSrc, int width, int height, int size_frame, cv::Mat& matDst)
{
// BGRA <--> NV21
cv::Mat matBGRA, matNV21;
cv::cvtColor(matSrc, matBGRA, cv::COLOR_BGR2BGRA);
uchar* pNV21 = new uchar[width * height + ((width + 1) / 2) * ((height + 1) / 2) * 2];
memset(pNV21, 0, sizeof(uchar) * (width * height + ((width + 1) / 2) * ((height + 1) / 2) * 2));
uchar* dst_y = pNV21;
int dst_y_stride = width;
uchar* dst_vu = pNV21 + size_frame;
int dst_vu_stride = (width + 1) / 2 * 2;
libyuv::ARGBToNV21(matBGRA.data, width * 4, dst_y, dst_y_stride, dst_vu, dst_vu_stride, width, height);
matNV21 = cv::Mat(height, width, CV_8UC4, cv::Scalar::all(0));
libyuv::NV21ToARGB(dst_y, dst_y_stride, dst_vu, dst_vu_stride, matNV21.data, width * 4, width, height);
cv::imwrite("NV21_bgra.jpg", matNV21);
matNV21.copyTo(matDst);
int count_diff = 0;
int max_diff = 0;
int threshold = 20;//
for (int i = 0; i < height; i++) {
uchar* pSrc = matBGRA.ptr(i);
uchar* pDst = matNV21.ptr(i);
for (int j = 0, m = 0; j < width; j++, m += 4) {
int tmp = std::max(abs(pSrc[m] - pDst[m]), abs(pSrc[m + 1] - pDst[m + 1]));
tmp = std::max(tmp, abs(pSrc[m + 2] - pDst[m + 2]));
if (tmp > max_diff)
max_diff = tmp;
if (abs(pSrc[m] - pDst[m]) > threshold ||
abs(pSrc[m + 1] - pDst[m + 1]) > threshold ||
abs(pSrc[m + 2] - pDst[m + 2]) > threshold) {
count_diff++;
//std::cout << i << " " << j << std::endl;
}
}
}
std::cout << "convert NV21 to BGRA diff max: " << max_diff << std::endl;
if (count_diff > width + height) {//
std::cout << "convert NV21 to BGRA error." << std::endl;
std::cout << "diff num: " << count_diff << std::endl;
}
delete[] pNV21;
}

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