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https://github.com/cesanta/mongoose.git
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e1dd3f06fe
PUBLISHED_FROM=c9cc54df1883aa17606de2b1ffb30f0cd687d037
169 lines
4.9 KiB
C
169 lines
4.9 KiB
C
/*
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* Copyright (c) 2014 Cesanta Software Limited
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* All rights reserved
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*/
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/*
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* This is the device endpoint of the Raspberry Pi camera/LED example
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* of the Mongoose networking library.
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* It is a simple websocket client, sending jpeg frames obtained from the
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* RPi camera and receiving JSON commands through the same WebSocket channel
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*/
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#include <unistd.h>
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#include "mongoose.h"
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static int s_poll_interval_ms = 100;
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static int s_still_period = 100;
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static int s_vertical_flip = 0;
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static int s_width = 320;
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static int s_height = 180;
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static const char *s_mjpg_file = "/var/run/shm/cam.jpg";
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static struct mg_connection *client;
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/*
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* Check if there is a new image available and
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* send it to the cloud endpoint if the send buffer is not too full.
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* The image is moved in a new file by the jpeg optimizer function;
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* this ensures that we will detect a new frame when raspistill writes
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* it's output file.
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*/
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static void send_mjpg_frame(struct mg_connection *nc, const char *file_path) {
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static int skipped_frames = 0;
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struct stat st;
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FILE *fp;
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/* Check file modification time. */
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if (stat(file_path, &st) == 0) {
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/* Skip the frame if there is too much unsent data. */
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if (nc->send_mbuf.len > 256) skipped_frames++;
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/* Read new mjpg frame into a buffer */
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fp = fopen(file_path, "rb");
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char buf[st.st_size];
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fread(buf, 1, sizeof(buf), fp);
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fclose(fp);
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/*
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* Delete the file so we can detect when raspistill creates a new one.
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* mtime granularity is only 1s.
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*/
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unlink(file_path);
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/* Send those buffer through the websocket connection */
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mg_send_websocket_frame(nc, WEBSOCKET_OP_BINARY, buf, sizeof(buf));
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printf("Sent mjpg frame, %lu bytes after skippping %d frames\n", (unsigned long) sizeof(buf), skipped_frames);
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skipped_frames = 0;
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}
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}
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/*
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* Turn on or off the LED.
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* The LED in this example is an RGB led, so all the colors have to be set.
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*/
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static void set_led(int v) {
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char cmd[512];
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snprintf(cmd, sizeof(cmd), "for i in 22 23 24; do"
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" echo %d >/sys/class/gpio/gpio$i/value; done", v);
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system(cmd);
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}
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/*
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* Parse control JSON and perform command:
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* for now only LED on/off is supported.
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*/
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static void perform_control_command(const char* data, size_t len) {
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struct json_token toks[200], *onoff;
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parse_json(data, len, toks, sizeof(toks));
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onoff = find_json_token(toks, "onoff");
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set_led(strncmp("[\"on\"]", onoff->ptr, onoff->len) == 0);
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}
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/* Main event handler. Sends websocket frames and receives control commands */
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static void ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
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struct websocket_message *wm = (struct websocket_message *) ev_data;
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switch (ev) {
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case MG_EV_CONNECT:
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printf("Reconnect: %s\n", * (int *) ev_data == 0 ? "ok" : "failed");
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if (* (int *) ev_data == 0) {
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/*
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* Tune the tcp send buffer size, so that we can skip frames
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* when the connection is congested. This helps maintaining a
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* reasonable latency.
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*/
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int sndbuf_size = 512;
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if(setsockopt(nc->sock, SOL_SOCKET, SO_SNDBUF,
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(void *) &sndbuf_size, sizeof(int)) == -1) {
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perror("failed to tune TCP send buffer size\n");
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}
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mg_send_websocket_handshake(nc, "/stream", NULL);
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}
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break;
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case MG_EV_CLOSE:
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printf("Connection %p closed\n", nc);
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client = NULL;
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break;
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case MG_EV_POLL:
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send_mjpg_frame(nc, s_mjpg_file);
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break;
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case MG_EV_WEBSOCKET_FRAME:
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printf("Got control command: [%.*s]\n", (int) wm->size, wm->data);
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perform_control_command((const char*)wm->data, wm->size);
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break;
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}
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}
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/*
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* This thread regenerates s_mjpg_file every s_poll_interval_ms milliseconds.
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* It is Raspberry PI specific, change this function on other systems.
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*/
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static void *generate_mjpg_data_thread_func(void *param) {
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char cmd[400];
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(void) param;
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snprintf(cmd, sizeof(cmd), "raspistill -w %d -h %d -n -q 100 -tl %d "
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"-t 999999999 -v %s -o %s >/dev/null 2>&1", s_width, s_height,
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s_still_period, s_vertical_flip ? "-vf" : "", s_mjpg_file);
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for(;;) {
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int ret = system(cmd);
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if (WIFSIGNALED(ret)) exit(1);
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sleep(1);
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}
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return NULL;
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}
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int main(int argc, char *argv[]) {
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struct mg_mgr mgr;
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char *addr = argv[1];
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if (argc < 2) {
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fprintf(stderr, "Usage: %s <server_address>\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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/* Start separate thread that generates MJPG data */
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mg_start_thread(generate_mjpg_data_thread_func, NULL);
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printf("Streaming [%s] to [%s]\n", s_mjpg_file, addr);
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mg_mgr_init(&mgr, NULL);
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for(;;) {
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mg_mgr_poll(&mgr, s_poll_interval_ms);
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/* Reconnect if disconnected */
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if (!client) {
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sleep(1); /* limit reconnections frequency */
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printf("Reconnecting to %s...\n", addr);
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client = mg_connect(&mgr, addr, ev_handler);
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if (client) mg_set_protocol_http_websocket(client);
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}
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}
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return EXIT_SUCCESS;
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}
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