support single-frame capture

README.md

@@ -27,6 +27,7 @@ Connect to the device's access point (e.g., FTYC811847AGFDZ) and run `node dist/
 
 ## Running
 
+### HTTP Server
 To execute the HTTP server, run `node dist/bin.cjs http_server`; you can access the JPEG stream at http://localhost:5000/.
 
 The roundtrip delay when using MJPEG is [~350ms](pics/delay.jpg?raw=true).
@@ -38,9 +39,9 @@ There's a basic UI which can display multiple cameras:
 Clicking on the image will take you to a page that has audio streaming. Click the button below the image to mute/unmute the audio.
 
 
-## Settings
+#### Settings
 
-You can provide a config file in `yml` format, check `config.example.yml` for an updated example:
+You can provide a config file in `yml` format, then pass it as an argument: `node bin.cjs http_server --config_file <your_config.yml>`
 
 ```yml
 http_server:
@@ -82,6 +83,12 @@ All keys are optional
 
 You must restart the HTTP server for changes to the settings file to take effect.
 
+### Single capture mode
+
+```bash
+node bin.cjs frame --discovery_ip 192.168.40.104 --out out.jpg 
+```
+
 ----
 
 ## Protocol

capture_single.ts

@@ -0,0 +1,39 @@
+import fs from "node:fs";
+import { DevSerial } from "./impl.js";
+import { RemoteInfo } from "dgram";
+import { logger } from "./logger.js";
+import { startVideoStream } from "./session.js";
+import { discoverDevices } from "./discovery.js";
+import { Session } from "./session.js";
+import { Handlers, makeSession } from "./session.js";
+import { config } from "./settings.js";
+
+const sessions: Record<string, Session> = {};
+export const captureSingle = ({ discovery_ip, out_file }: { discovery_ip: string; out_file: string }) => {
+  let devEv = discoverDevices([discovery_ip]);
+
+  const startSession = (s: Session) => {
+    startVideoStream(s);
+    logger.info(`Camera ${s.devName} is now ready to stream`);
+  };
+
+  devEv.on("discover", (rinfo: RemoteInfo, dev: DevSerial) => {
+    if (dev.devId in sessions) {
+      logger.info(`Camera ${dev.devId} at ${rinfo.address} already discovered, ignoring`);
+      return;
+    }
+
+    logger.info(`Discovered camera ${dev.devId} at ${rinfo.address}`);
+    const s = makeSession(Handlers, dev, rinfo, startSession, 5000);
+    sessions[dev.devId] = s;
+    config.cameras[dev.devId] = { fix_packet_loss: false };
+
+    s.eventEmitter.on("frame", () => {
+      const assembled = Buffer.concat(s.curImage);
+      fs.writeFileSync(out_file, assembled);
+      logger.info(`Got frame. Exiting`);
+      devEv.emit("close");
+      s.close();
+    });
+  });
+};

cmd/bin.ts

@@ -2,6 +2,7 @@ import process from "node:process";
 import { hideBin } from "yargs/helpers";
 import yargs from "yargs/yargs";
 
+import { captureSingle } from "../capture_single.js";
 import { serveHttp } from "../http_server.js";
 import { pair } from "../pair.js";
 import { loadConfig, config } from "../settings.js";
@@ -70,5 +71,24 @@ yargs(hideBin(process.argv))
       pair({ ssid: argv.ssid, password: argv.password });
     },
   )
+  .command(
+    "frame",
+    "capture a single frame from the first discovered camera",
+    (yargs) => {
+      return yargs
+        .option("log_level", { describe: "Set log level", default: "info" })
+        .option("discovery_ip", { describe: "Camera discovery IP address", default: "192.168.1.255" })
+        .option("out", { describe: "Path for output file" })
+        .demandOption(["out"])
+        .string(["out", "discovery_ip"]);
+    },
+    (argv) => {
+      buildLogger(argv.log_level, undefined);
+      if (majorVersion < 16) {
+        logger.error(`Node version ${majorVersion} is not supported, may malfunction`);
+      }
+      captureSingle({ discovery_ip: argv.discovery_ip, out_file: argv.out });
+    },
+  )
   .demandCommand()
   .parseSync();

handlers.ts

@@ -249,7 +249,7 @@ const deal_with_data = (session: Session, dv: DataView) => {
         }
         // this should always be enabled but currently it seems to cause more
         // visual distortion than just missing some frames
-        if (!config.cameras[session.devName].fix_packet_loss) {
+        if (!config.cameras[session.devName]?.fix_packet_loss) {
           return;
         }