Add support for KLV Data (SMPTE336M)

CHANGELOG.md

@@ -1,4 +1,5 @@
 # Next Release
+Add SMPTE336M and STANAG 4609 KLV parsing and writing to a raw .klv data file. Testing by passing MPEGTS with KLV data into a recent version of MediaMTX that outputs KLV over RTSP
 
 # 3.0.8 - 15th January 2027
 Add caching Digest Authentication code from Leone25 Enrico

README.md

@@ -28,6 +28,7 @@ Yellowstone is co-developed by Michael Bullington and Roger Hardiman.
 - ONVIF Metadata parsing (and writing to an output file)
 - ONVIF extensions to RTSP
 - ONVIF Audio Backchannel, sending ALaw audio to an IP Camera
+- SMPTE336M KLV (STANAG 4609) KLV parsing (and writing to a .klv file)
 - Simple RTCP parsing
 
 ## Examples

dist/index.d.ts

@@ -3,8 +3,9 @@ import H265Transport from "./transports/H265Transport";
 import H266Transport from "./transports/H266Transport";
 import AV1Transport from "./transports/AV1Transport";
 import AACTransport from "./transports/AACTransport";
+import SMPTE336MKLVTransport from "./transports/SMPTE336MKLVTransport";
 import ONVIFMetadataTransport from "./transports/ONVIFMetadataTransport";
 import ONVIFClient from "./ONVIFClient";
 import RTSPClient from "./RTSPClient";
 import { RTPPacket, RTCPPacket } from "./util";
-export { H264Transport, H265Transport, H266Transport, AV1Transport, AACTransport, ONVIFMetadataTransport, ONVIFClient, RTSPClient, RTPPacket, RTCPPacket };
+export { H264Transport, H265Transport, H266Transport, AV1Transport, AACTransport, SMPTE336MKLVTransport, ONVIFMetadataTransport, ONVIFClient, RTSPClient, RTPPacket, RTCPPacket };

dist/transports/SMPTE336MKLVTransport.d.ts

@@ -0,0 +1,20 @@
+/// <reference types="node" />
+/// <reference types="node" />
+import RTSPClient from "../RTSPClient";
+import { RTPPacket } from "../util";
+import * as transform from "sdp-transform";
+import { Writable } from "stream";
+interface Details {
+    codec: string;
+    mediaSource: transform.MediaDescription;
+    rtpChannel: number;
+    rtcpChannel: number;
+}
+export default class SMPTE336MKLVTransport {
+    client: RTSPClient;
+    stream: Writable;
+    rawData: Buffer[];
+    constructor(client: RTSPClient, stream: Writable, details: Details);
+    processRTPPacket(packet: RTPPacket): void;
+}
+export {};

examples/demo.js

@@ -13,7 +13,7 @@
 
 // Used to connect to Wowza Demo URL but they have taken it away, and the replacement URL on their web site does not work.
 
-const { RTSPClient, H264Transport, H265Transport, H266Transport, AV1Transport, AACTransport } = require("../dist");
+const { RTSPClient, H264Transport, H265Transport, H266Transport, AV1Transport, AACTransport, SMPTE336MKLVTransport } = require("../dist");
 const fs = require("fs");
 const { exit } = require("process");
 const { program } = require("commander");
@@ -96,6 +96,12 @@ client.connect(url, { connection: transport, secure: false })
         // This class subscribes to the client 'data' event, looking for the audio payload
         const aac = new AACTransport(client, audioFile, details);
       }
+      if (details.codec == "SMPTE336M") {
+        const klvFile = fs.createWriteStream(filename + '.klv');
+        // Add KLV Transport
+        // This class subscribes to the client 'data' event, looking for the KLV payload
+        const klv = new SMPTE336MKLVTransport(client, klvFile, details);
+      }
     }
 
     // Step 5: Start streaming!

lib/RTSPClient.ts

@@ -387,6 +387,19 @@ export default class RTSPClient extends EventEmitter {
         }
       }
 
+      if (
+        mediaSource.type === "application" &&
+        mediaSource.protocol === RTP_AVP &&
+        mediaSource.rtp[0].codec.toUpperCase() === "SMPTE336M" // MediaMTX sends in capitals. Looks like the RFC suggests lower case
+      ) {
+        this.emit("log", "SMPTE336M KLV Data Stream Found in SDP", "");
+        if (hasMetaData == false) {
+          needSetup = true;
+          hasMetaData = true;
+          codec = "SMPTE336M";
+        }
+      }
+
       if (needSetup) {
         let streamurl = "";
         // The 'control' in the SDP can be a relative or absolute uri

lib/index.ts

@@ -3,6 +3,7 @@ import H265Transport from "./transports/H265Transport";
 import H266Transport from "./transports/H266Transport";
 import AV1Transport from "./transports/AV1Transport";
 import AACTransport from "./transports/AACTransport";
+import SMPTE336MKLVTransport from "./transports/SMPTE336MKLVTransport";
 import ONVIFMetadataTransport from "./transports/ONVIFMetadataTransport";
 import ONVIFClient from "./ONVIFClient";
 import RTSPClient from "./RTSPClient";
@@ -14,6 +15,7 @@ export {
   H266Transport,
   AV1Transport,
   AACTransport,
+  SMPTE336MKLVTransport,
   ONVIFMetadataTransport,
   ONVIFClient,
   RTSPClient,

lib/transports/H264Transport.ts

@@ -49,19 +49,35 @@ export default class H264Transport {
       return;
     }
 
+    // Normally the SDP includes the sprop-parameter-sets with the SPS and PPS data
+    // However for MPEGTS converted to RTSP with MediaMTX, there is no sprop-parameter-sets
     const fmtpConfig = transform.parseParams(fmtp.config);
-    const splitSpropParameterSets = fmtpConfig['sprop-parameter-sets'].toString().split(',');
-    const sps_base64 = splitSpropParameterSets[0];
-    const pps_base64 = splitSpropParameterSets[1];
-    const sps = Buffer.from(sps_base64, "base64");
-    const pps = Buffer.from(pps_base64, "base64");
-
-    this.stream.write(H264_HEADER);
-    this.stream.write(sps);
-    this.stream.write(H264_HEADER);
-    this.stream.write(pps);
-
-    this._headerWritten = true;
+    if ('sprop-parameter-sets' in fmtpConfig) {
+      const splitSpropParameterSets = fmtpConfig['sprop-parameter-sets'].toString().split(',');
+      const sps_base64 = splitSpropParameterSets[0];
+      const pps_base64 = splitSpropParameterSets[1];
+      const sps = Buffer.from(sps_base64, "base64");
+      const pps = Buffer.from(pps_base64, "base64");
+
+      this.stream.write(H264_HEADER);
+      this.stream.write(sps);
+      this.stream.write(H264_HEADER);
+      this.stream.write(pps);
+
+      this._headerWritten = true;
+    }
+    else
+    {
+      // Ideally MediaMTX would have parsed the MPEGTS stream, extracted the SPS and PPS and then
+      // placed it in the RTSP DESCRIBE SDP, but it does not do that.
+      // The correct method is to parse the RTP Payloads until we see the NAL type for SPS
+      // and the NAL type for PPS, then we can write them and set this._headerWritten to true
+
+      // But for now we will just set this._headerWritten to true and let NALS be written to disk
+      // before the first SPS and PPS data
+      this._headerWritten = true; // HACK - should be parsing the NALs for SPS and PPS
+    }
+
   }
 
   processRTPPacket(packet: RTPPacket): void {

lib/transports/SMPTE336MKLVTransport.ts

@@ -0,0 +1,52 @@
+// De-packetize RC 6597 RTP packets to re-create SMPTE336M KLV Metadata including STANAG 4609
+// Write data to a file as raw binary data.
+// The RTP timestamp is not saved to the file.
+// By Roger Hardiman, January 2026
+
+import RTSPClient from "../RTSPClient";
+import { RTPPacket } from "../util";
+
+import * as transform from "sdp-transform";
+import { Writable } from "stream";
+
+interface Details {
+  codec: string;
+  mediaSource: transform.MediaDescription;
+  rtpChannel: number;
+  rtcpChannel: number;
+}
+
+export default class SMPTE336MKLVTransport {
+  client: RTSPClient;
+  stream: Writable;
+  rawData: Buffer[];
+
+  constructor(client: RTSPClient, stream: Writable, details: Details) {
+    this.client = client;
+    this.stream = stream;
+    this.rawData = [];
+
+    client.on("data", (channel, data, packet) => {
+      if (channel == details.rtpChannel) {
+        this.processRTPPacket(packet);
+      }
+    });
+  }
+
+  processRTPPacket(packet: RTPPacket): void {
+    // RTP Payload for ONVIF Metadata
+
+    // Accumulate payload
+    this.rawData.push(packet.payload)
+
+    if (packet.marker == 1) {  // TODO... OR if the Timestamp has changed
+      // end of data. Write the file
+      // In this case we can just write each Buffer from the rawData array
+      // If we were passing the KLV to a caller, we would concatenate the Buffers in the rawData array first
+      for(const buffer of this.rawData) {
+        this.stream.write(buffer);
+      }
+      this.rawData = [];
+    }
+  }
+}