/* * Copyright (c) 2014 Cesanta Software Limited * All rights reserved */ /* * This is the device endpoint of the Raspberry Pi camera/LED example * of the Mongoose networking library. * It is a simple websocket client, sending jpeg frames obtained from the * RPi camera and receiving JSON commands through the same WebSocket channel */ #include #include "mongoose.h" static int s_poll_interval_ms = 100; static int s_still_period = 100; static int s_vertical_flip = 0; static int s_width = 320; static int s_height = 180; static const char *s_mjpg_file = "/var/run/shm/cam.jpg"; static struct mg_connection *client; /* * Check if there is a new image available and * send it to the cloud endpoint if the send buffer is not too full. * The image is moved in a new file by the jpeg optimizer function; * this ensures that we will detect a new frame when raspistill writes * it's output file. */ static void send_mjpg_frame(struct mg_connection *nc, const char *file_path) { static int skipped_frames = 0; struct stat st; FILE *fp; /* Check file modification time. */ if (stat(file_path, &st) == 0) { /* Skip the frame if there is too much unsent data. */ if (nc->send_mbuf.len > 256) skipped_frames++; /* Read new mjpg frame into a buffer */ fp = fopen(file_path, "rb"); char buf[st.st_size]; fread(buf, 1, sizeof(buf), fp); fclose(fp); /* * Delete the file so we can detect when raspistill creates a new one. * mtime granularity is only 1s. */ unlink(file_path); /* Send those buffer through the websocket connection */ mg_send_websocket_frame(nc, WEBSOCKET_OP_BINARY, buf, sizeof(buf)); printf("Sent mjpg frame, %lu bytes after skippping %d frames\n", (unsigned long) sizeof(buf), skipped_frames); skipped_frames = 0; } } /* * Turn on or off the LED. * The LED in this example is an RGB led, so all the colors have to be set. */ static void set_led(int v) { char cmd[512]; snprintf(cmd, sizeof(cmd), "for i in 22 23 24; do" " echo %d >/sys/class/gpio/gpio$i/value; done", v); system(cmd); } /* * Parse control JSON and perform command: * for now only LED on/off is supported. */ static void perform_control_command(const char* data, size_t len) { struct json_token toks[200], *onoff; parse_json(data, len, toks, sizeof(toks)); onoff = find_json_token(toks, "onoff"); set_led(strncmp("[\"on\"]", onoff->ptr, onoff->len) == 0); } /* Main event handler. Sends websocket frames and receives control commands */ static void ev_handler(struct mg_connection *nc, int ev, void *ev_data) { struct websocket_message *wm = (struct websocket_message *) ev_data; switch (ev) { case MG_EV_CONNECT: printf("Reconnect: %s\n", * (int *) ev_data == 0 ? "ok" : "failed"); if (* (int *) ev_data == 0) { /* * Tune the tcp send buffer size, so that we can skip frames * when the connection is congested. This helps maintaining a * reasonable latency. */ int sndbuf_size = 512; if(setsockopt(nc->sock, SOL_SOCKET, SO_SNDBUF, (void *) &sndbuf_size, sizeof(int)) == -1) { perror("failed to tune TCP send buffer size\n"); } mg_send_websocket_handshake(nc, "/stream", NULL); } break; case MG_EV_CLOSE: printf("Connection %p closed\n", nc); client = NULL; break; case MG_EV_POLL: send_mjpg_frame(nc, s_mjpg_file); break; case MG_EV_WEBSOCKET_FRAME: printf("Got control command: [%.*s]\n", (int) wm->size, wm->data); perform_control_command((const char*)wm->data, wm->size); break; } } /* * This thread regenerates s_mjpg_file every s_poll_interval_ms milliseconds. * It is Raspberry PI specific, change this function on other systems. */ static void *generate_mjpg_data_thread_func(void *param) { char cmd[400]; (void) param; snprintf(cmd, sizeof(cmd), "raspistill -w %d -h %d -n -q 100 -tl %d " "-t 999999999 -v %s -o %s >/dev/null 2>&1", s_width, s_height, s_still_period, s_vertical_flip ? "-vf" : "", s_mjpg_file); for(;;) { int ret = system(cmd); if (WIFSIGNALED(ret)) exit(1); sleep(1); } return NULL; } int main(int argc, char *argv[]) { struct mg_mgr mgr; char *addr = argv[1]; if (argc < 2) { fprintf(stderr, "Usage: %s \n", argv[0]); exit(EXIT_FAILURE); } /* Start separate thread that generates MJPG data */ mg_start_thread(generate_mjpg_data_thread_func, NULL); printf("Streaming [%s] to [%s]\n", s_mjpg_file, addr); mg_mgr_init(&mgr, NULL); for(;;) { mg_mgr_poll(&mgr, s_poll_interval_ms); /* Reconnect if disconnected */ if (!client) { sleep(1); /* limit reconnections frequency */ printf("Reconnecting to %s...\n", addr); client = mg_connect(&mgr, addr, ev_handler); if (client) mg_set_protocol_http_websocket(client); } } return EXIT_SUCCESS; }