android – 使用FFmpeg检索专辑封面

我正在开发一个依赖于FFmpeg来检索音频元数据的 Android应用程序.我知道可以使用FFMpeg以编程方式检索专辑封面.但是,一旦您解码了艺术(MP3中的视频帧),如何生成图像文件(PNG)以便在应用程序中使用？我搜遍了所有但似乎无法找到一个有效的例子.

编辑,这是解决方案：

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>

void retrieve_album_art(const char *path,const char *album_art_file) {
    int i,ret = 0;

    if (!path) {
        printf("Path is NULL\n");
        return;
    }

    AVFormatContext *pformatCtx = avformat_alloc_context();

    printf("opening %s\n",path);

    // open the specified path
    if (avformat_open_input(&pformatCtx,path,NULL,NULL) != 0) {
        printf("avformat_open_input() Failed");
        goto fail;
    }

    // read the format headers
    if (pformatCtx->iformat->read_header(pformatCtx) < 0) {
        printf("Could not read the format header\n");
        goto fail;
    }

    // find the first attached picture,if available
    for (i = 0; i < pformatCtx->nb_streams; i++)
        if (pformatCtx->streams[i]->disposition & AV_disPOSITION_ATTACHED_PIC) {
            AVPacket pkt = pformatCtx->streams[i]->attached_pic;
            FILE* album_art = fopen(album_art_file,"wb");
            ret = fwrite(pkt.data,pkt.size,1,album_art);
            fclose(album_art);
            av_free_packet(&pkt);
            break;
        }

    if (ret) {
        printf("Wrote album art to %s\n",album_art_file);
    }

    fail:
        av_free(pformatCtx);
        // this line crashes for some reason...
        //avformat_free_context(pformatCtx);
}

int main() {
    avformat_network_init();
    av_register_all();

    const char *path = "some url";
    const char *album_art_file = "some path";

    retrieve_album_art(path,album_art_file);

    return 0;
}

ffmpeg -i input.mp3 -an -vcodec copy cover.jpg

AVFormatContext* fmt_ctx;
// set up fmt_ctx to read first video stream
AVPacket pkt;
av_read_frame(fmt_ctx,&pkt);
FILE* image_file = fopen("image.jpg","wb");
int result = fwrite(pkt.data,image_file);
fclose(image_file);