yuv420p旋转

void Rotate90(const AVFrame* src, AVFrame* dst)
{
    int half_width = src->width >> 1;
    int half_height = src->height >> 1;




    int size = src->linesize[0] * src->height;
    int half_size = size >> 2;




    for (int j = 0, n = 0; j < src->width; j++) {
        int pos = size;
        for (int i = src->height - 1; i >= 0; i--) {
            pos -= src->linesize[0];
            dst->data[0][n++] = src->data[0][pos + j];
        }
    }




    for (int j = 0, n = 0; j < half_width; j++) {
        int pos = half_size;
        for (int i = half_height - 1; i >= 0; i--) {
            pos -= src->linesize[1];
            dst->data[1][n] = src->data[1][pos + j];
            dst->data[2][n++] = src->data[2][pos + j];
        }
    }




    dst->height = src->width;
    dst->width  = src->height;
}




void Rotate180(const AVFrame* src, AVFrame* dst)
{
    int half_width = src->width >> 1;
    int half_height = src->height >> 1;




    int pos = src->linesize[0] * src->height;
    for (int i = 0, n = 0; i < src->height; i++) {
        pos -= src->linesize[0];
        for (int j = src->width - 1; j >= 0; j--) {
            dst->data[0][n++] = src->data[0][pos + j];
        }
    }




    pos = src->linesize[0] * src->height >> 2;
    for (int i = 0, n = 0; i < half_height; i++) {
        pos -= src->linesize[1];
        for (int j = half_width - 1; j >= 0; j--) {
            dst->data[1][n] = src->data[1][pos + j];
            dst->data[2][n++] = src->data[2][pos + j];
        }
    }




    dst->width  = src->width;
    dst->height = src->height;
}




void Rotate270(const AVFrame* src, AVFrame* dst)
{
    int half_width = src->linesize[0] >> 1;
    int half_height = src->height >> 1;




    for (int i = src->width - 1, n = 0; i >= 0; i--) {
        for (int j = 0, pos = 0; j < src->height; j++) {
            dst->data[0][n++] = src->data[0][pos + i];
            pos += src->linesize[0];
        }
    }




    for (int i = (src->width >> 1) - 1, n = 0; i >= 0; i--) {
        for (int j = 0, pos = 0; j < half_height; j++) {
            dst->data[1][n] = src->data[1][pos + i];
            dst->data[2][n++] = src->data[2][pos + i];
            pos += half_width;
        }
    }




    dst->width = src->height;
    dst->height = src->width;
}

参考 https://blog.csdn.net/veilling/article/details/52200326