因此,我尝试使用webp API编码图像。现在,我将使用openCV打开和处理图像,然后将其保存为webp。这是我正在使用的来源:

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <cv.h>
#include <highgui.h>
#include <webp/encode.h>

int main(int argc, char *argv[])
{

    IplImage* img = 0;
    int height,width,step,channels;
    uchar *data;
    int i,j,k;
    if (argc<2) {
        printf("Usage:main <image-file-name>\n\7");
    exit(0);
    }
    // load an image
    img=cvLoadImage(argv[1]);

    if(!img){
        printf("could not load image file: %s\n",argv[1]);
        exit(0);
    }

    // get the image data
    height      = img->height;
    width       = img->width;
    step        = img->widthStep;
    channels    = img->nChannels;
    data        = (uchar *)img->imageData;
    printf("processing a %dx%d image with %d channels \n", width, height, channels);

    // create a window
    cvNamedWindow("mainWin", CV_WINDOW_AUTOSIZE);
    cvMoveWindow("mainWin",100,100);

    // invert the image
    for (i=0;i<height;i++) {
        for (j=0;j<width;j++) {
            for (k=0;k<channels;k++) {
                data[i*step+j*channels+k] = 255-data[i*step+j*channels+k];
            }
        }
    }

    // show the image
    cvShowImage("mainWin", img);

    // wait for a key
    cvWaitKey(0);
    // release the image
    cvReleaseImage(&img);

    float qualityFactor = .9;
    uint8_t** output;
    FILE *opFile;
    size_t datasize;
    printf("encoding image\n");
    datasize = WebPEncodeRGB((uint8_t*)data,width,height,step,qualityFactor,output);

    printf("writing file out\n");
    opFile=fopen("output.webp","w");
    fwrite(output,1,(int)datasize,opFile);
}

当执行此命令时,我得到以下信息:
nato@ubuntu:~/webp/webp_test$ ./helloWorld ~/Pictures/mars_sunrise.jpg
processing a 2486x1914 image with 3 channels
encoding image
Segmentation fault

它显示图像很好,但是在编码上存在段错误。我最初的猜测是,这是因为我在尝试写出数据之前就发布了img,但是在尝试编码之前还是之后发布都似乎无关紧要。我还有其他可能会导致此问题的东西吗?是否需要复制图像数据或其他内容?

WebP api文档稀疏。这是自述文件中关于WebPEncodeRGB的内容:
The main encoding functions are available in the header src/webp/encode.h
The ready-to-use ones are:

size_t WebPEncodeRGB(const uint8_t* rgb, int width, int height,
    int stride, float quality_factor, uint8_t** output);

文档没有具体说明“步幅”是什么,但是我假设它与opencv的“步骤”相同。那合理吗?

提前致谢!

最佳答案

首先,如果以后使用它,请不要释放它。其次,您的输出参数指向未初始化的地址。这是将初始化的内存用于输出地址的方法:

uint8_t* output;
datasize = WebPEncodeRGB((uint8_t*)data, width, height, step, qualityFactor, &output);

关于c++ - WebP编码-段错误,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/10196671/

10-12 23:50