用Qt调用ffmpeg接口的简单例子

下面是一个简单的使用Qt调用FFmpeg接口的例子：

#include <QCoreApplication>
#include <QDebug>
#include <QString>
#include <QByteArray>
#include <QFile>
#include <QDir>
#include <QProcess>
#include <iostream>

extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/imgutils.h>
}

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

    // 注册所有FFmpeg组件
    av_register_all();

    // 打开输入文件
    AVFormatContext *pFormatCtx = NULL;
    if (avformat_open_input(&pFormatCtx, "input.mp4", NULL, NULL) != 0) {
        qCritical() << "Could not open input file" << endl;
        return -1;
    }

    // 获取流信息
    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        qCritical() << "Could not find stream information" << endl;
        return -1;
    }

    // 找到视频流
    int videoStream = -1;
    for (int i = 0; i < pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            videoStream = i;
            break;
        }
    }
    if (videoStream == -1) {
        qCritical() << "Could not find video stream" << endl;
        return -1;
    }

    // 获取视频解码器
    AVCodecParameters *pCodecParams = pFormatCtx->streams[videoStream]->codecpar;
    AVCodec *pCodec = avcodec_find_decoder(pCodecParams->codec_id);
    if (pCodec == NULL) {
        qCritical() << "Could not find codec" << endl;
        return -1;
    }

    // 打开解码器
    AVCodecContext *pCodecCtx = avcodec_alloc_context3(pCodec);
    if (avcodec_parameters_to_context(pCodecCtx, pCodecParams) < 0) {
        qCritical() << "Could not copy codec parameters to decoder context" << endl;
        return -1;
    }
    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
        qCritical() << "Could not open codec" << endl;
        return -1;
    }

    // 获取帧缓冲
    AVFrame *pFrame = av_frame_alloc();
    if (pFrame == NULL) {
        qCritical() << "Could not allocate frame" << endl;
        return -1;
    }

    // 读取视频帧
    AVPacket packet;
    int frameCount = 0;
    while (av_read_frame(pFormatCtx, &packet) >= 0) {
        if (packet.stream_index == videoStream) {
            // 解码视频帧
            int ret = avcodec_send_packet(pCodecCtx, &packet);
            if (ret < 0) {
                qCritical() << "Error sending packet to decoder" << endl;
                return -1;
            }
            while (ret >= 0) {
                ret = avcodec_receive_frame(pCodecCtx, pFrame);
                if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
                    break;
                } else if (ret < 0) {
                    qCritical() << "Error during decoding" << endl;
                    return -1;
                }

                // 处理视频帧
                std::cout << "Frame " << frameCount << " (type=" << pFrame->pict_type << ", size=" << pFrame->pkt_size << ")" << std::endl;

                frameCount++;
            }
        }

        av_packet_unref(&packet);
    }

    // 释放资源
    avcodec_free_context(&pCodecCtx);
    avformat_close_input(&pFormatCtx);
    avformat_free_context(pFormatCtx);
    av_frame_free(&pFrame);

    return a.exec();
}

这个例子演示了如何使用FFmpeg解码视频帧。请注意，此代码仅为示例，实际使用时可能需要进行更多的错误处理和资源管理。