Merge dev branch code named Fossa as next stable Mongoose

examples/raspberry_pi_mjpeg_led/device_side.c

@@ -0,0 +1,168 @@
+/*
+ * 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 <unistd.h>
+#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 NS_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 NS_CLOSE:
+      printf("Connection %p closed\n", nc);
+      client = NULL;
+      break;
+    case NS_POLL:
+      send_mjpg_frame(nc, s_mjpg_file);
+      break;
+    case NS_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 <server_address>\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;
+}