QImage与AVFrame互转

先是AVFrame转QImage

#pragma execution_character_set("utf-8")


static int decode_write_frame(AVCodecContext *avctx, AVFrame *frame, int *frame_count, AVPacket *pkt, int last)
{
    int len, got_frame;
    char buf[1024];
    len = avcodec_decode_video2(avctx, frame, &got_frame, pkt);
    if (len < 0) {
        printf("Error while decoding frame %d\n", *frame_count);
        return len;
    }
    if (got_frame) {
        printf("Saving frame %3d\n", *frame_count);

        QImage image(QSize(avctx->width, avctx->height), QImage::Format_RGB888);

        for(int h = 0; h < avctx->height; h++)
        {
            for(int w = 0; w < avctx->width; w ++)
            {
                int hh = h >> 1;
                int ww = w >> 1;
                int Y = frame->data[0][h * frame->linesize[0] + w];
                int U = frame->data[1][hh * (frame->linesize[1]) + ww];
                int V = frame->data[2][hh * (frame->linesize[2]) + ww];

                int C = Y - 16;
                int D = U - 128;
                int E = V - 128;

                int r = 298 * C           + 409 * E + 128;
                int g = 298 * C - 100 * D - 208 * E + 128;
                int b = 298 * C + 516 * D           + 128;

                r = qBound(0, r >> 8, 255);
                g = qBound(0, g >> 8, 255);
                b = qBound(0, b >> 8, 255);

                r = qBound(0, r, 255);
                g = qBound(0, g, 255);
                b = qBound(0, b, 255);

                QRgb rgb = qRgb(r, g, b);
                image.setPixel(QPoint(w, h), rgb);
            }
        }

        QString fname = QString("img") + QString::number(*frame_count) + ".jpg";
        image.save(fname);


        //pgm_save(frame->data[0], frame->linesize[0], avctx->width, avctx->height, buf);
        (*frame_count)++;
    }
    if (pkt->data) {
        pkt->size -= len;
        pkt->data += len;
    }
    return 0;
}

然后是QImage转AVFrame

#pragma execution_character_set("utf-8")


QImage image = QPixmap::grabWindow(QApplication::desktop()->winId()).toImage();
    image = image.scaled(QSize(resize_width, resize_height));

    av_init_packet(pkt);
    pkt->data = NULL;    // packet data will be allocated by the encoder
    pkt->size = 0;

    for (int h = 0; h < context->height; h++)
    {
        for (int w = 0; w < context->width; w++)
        {
            QRgb rgb = image.pixel(w, h);

            int r = qRed(rgb);
            int g = qGreen(rgb);
            int b = qBlue(rgb);

            int dy = ((66*r + 129*g + 25*b) >> 8) + 16;
            int du = ((-38*r + -74*g + 112*b) >> 8) + 128;
            int dv = ((112*r + -94*g + -18*b) >> 8) + 128;

            uchar yy = (uchar)dy;
            uchar uu = (uchar)du;
            uchar vv = (uchar)dv;

            frame->data[0][h * frame->linesize[0] + w] = yy;

            if(h % 2 == 0 && w % 2 == 0)
            {
                frame->data[1][h/2 * (frame->linesize[1]) + w/2] = uu;
                frame->data[2][h/2 * (frame->linesize[2]) + w/2] = vv;
            }

        }
    }