c语言中怎么获取视频帧数

获取视频帧数需要使用视频处理库，比如FFmpeg。以下是使用FFmpeg获取视频帧数的示例代码：

#include <stdio.h>
#include <libavformat/avformat.h>

int main(int argc, char **argv)
{
    AVFormatContext *pFormatCtx = NULL;
    int i, videoStream;
    AVRational videoTimeBase;
    AVCodecParameters *pCodecPar = NULL;
    int64_t duration, totalFrames;

    if (argc < 2) {
        printf("Usage: %s <video_file>\n", argv[0]);
        return -1;
    }

    // Open video file
    if (avformat_open_input(&pFormatCtx, argv[1], NULL, NULL) != 0) {
        printf("Error: Could not open file '%s'\n", argv[1]);
        return -1;
    }

    // Retrieve stream information
    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        printf("Error: Could not find stream information\n");
        return -1;
    }

    // Dump information about file onto standard error
    av_dump_format(pFormatCtx, 0, argv[1], 0);

    // Find the first video stream
    videoStream = -1;
    for (i = 0; i < pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            videoStream = i;
            break;
        }
    }
    if (videoStream == -1) {
        printf("Error: Could not find video stream\n");
        return -1;
    }

    // Get video parameters
    pCodecPar = pFormatCtx->streams[videoStream]->codecpar;
    videoTimeBase = pFormatCtx->streams[videoStream]->time_base;

    // Calculate video duration and total frames
    duration = pFormatCtx->duration;
    totalFrames = (duration * pCodecPar->frame_rate.num + pCodecPar->frame_rate.den - 1) / pCodecPar->frame_rate.den;

    printf("File '%s':\n", argv[1]);
    printf("  Duration: %" PRId64 " seconds\n", duration / AV_TIME_BASE);
    printf("  Video stream:\n");
    printf("    Codec: %s\n", avcodec_get_name(pCodecPar->codec_id));
    printf("    Resolution: %dx%d\n", pCodecPar->width, pCodecPar->height);
    printf("    Frame rate: %.2f\n", (double)pCodecPar->frame_rate.num / pCodecPar->frame_rate.den);
    printf("    Total frames: %" PRId64 "\n", totalFrames);

    // Close video file
    avformat_close_input(&pFormatCtx);

    return 0;
}

编译代码需要链接FFmpeg库，比如使用以下命令：

gcc -o get_frames get_frames.c -lavformat

运行程序需要传递视频文件路径，比如：

./get_frames video.mp4

程序将输出视频文件的基本信息，包括总帧数。