Question

目前有一些C代码使用sigaction将处理程序与SIGALRM信号相关联。现在在代码中，VIDIOCSYNC ioctl on in＆gt; fd暂停执行，直到in-＆gt; buf已被填充。相同的网络摄像头设备可以飞轮，所以我的应用程序应该支持这些设备而不会阻止GUI。

#define SYNC_TIMEOUT 5

static int alarms;

static void sigalarm(int signal)
{
    alarms++;
}

static void siginit(void)
{
    struct sigaction act, old;

    memset(&act, 0, sizeof(act));
    act.sa_handler = sigalarm;
    sigemptyset(&act.sa_mask);
    sigaction(SIGALRM, &act, &old);
}

void wait_for_frame(input_t *in, int frameid)
{
        alarms = 0;
        alarm(SYNC_TIMEOUT);
        if (ioctl(in->fd, VIDIOCSYNC, in->buf + frameid) < 0) {
            fprintf(stderr, "input: Can't wait for frame %d: %s\n", frameid, strerror(errno));
    }
        if(alarms) {
            fprintf(stderr, "\n"
                        "Your capture card driver: %s\n"
                        "is taking too long to provide frames.  This could be due\n"
                        "either to a broken capture card, a signal that has become unstable\n"
                        "or very noisy, or a driver misconfiguration.\n",
                        in->drivername);
    }
    alarm(0);
}

我希望在这种情况下改变这一点：如果没有帧在100毫秒内到达，那么超时并让GUI有机会自行更新。

用秒秒警报（微秒）替换警报（安排警报信号）

0 个答案: