大家帮我看看这个线程的问题，好吗？ [复制链接]

vid_mmap等变量是全局的，
int v4lstart(int fd)
{
  if (ioctl (fd, VIDIOCMCAPTURE, &vid_mmap) == -1) {
        perror ("ioctl VIDIOCMCAPTURE");
        munmap (map, vid_buf.size);
        return -1;
    }
  vid_mmap.frame = 1;
    if (ioctl (fd, VIDIOCMCAPTURE, &vid_mmap) == -1) {
        perror ("ioctl VIDIOCMCAPTURE");
        munmap (map, vid_buf.size);
        return -1;
    }
    return 0;
}
char *v4lsyn(int fd,int i)
{int bytes = 3;
vid_mmap.frame = (i +1)%2;
    i++;
        if (ioctl (fd, VIDIOCSYNC, &vid_mmap.frame) == -1) {
          perror ("ioctl VIDIOCSYNC");
          munmap (map, vid_buf.size);
          return (NULL);
        }
map=map +vid_buf.offsets[vid_mmap.frame];
  /*if (palette == VIDEO_PALETTE_YUV420P) {
    if (verbose)
        fprintf (stderr, "converting from YUV to RGB\n");
    convmap = malloc ( width * height * bytes );
    v4l_yuv420p2rgb (convmap, map, width, height, bytes * 8);
    memcpy (map, convmap, (size_t) width * height * bytes);
    free (convmap);
    }*/
    convmap =(unsigned char *) malloc ( width * height * bytes );
    v4l_yuv420p2rgb (convmap, map, width, height, bytes * 8);
    memcpy (map, convmap, (size_t) width * height * bytes);
    free (convmap);
 
  return ((char *)map);
}
int v4lcapture(int fd)
{
if (ioctl (fd, VIDIOCMCAPTURE, &vid_mmap) == -1)
{
    perror ("ioctl VIDIOCMCAPTURE");
    munmap (map, vid_buf.size);
    return -1;
}
  sleep(50);
//munmap (map, vid_buf.size);
  return 0;
}
然后再程序中作了个循环
v4lbuf(dev1);
v4lmap(dev1);
v4lstart(dev1);

while(1)
{
  buffer=v4lsyn(dev1,i);
v4lcapture(dev1);
}
结果出现的错误是New Thread 1084981632 (LWP 4936)，请各位代谢阿帮忙分析一下，谢谢