NorskInput.srt() method

Stream from a SRT source

Signature:

srt(settings: SrtInputSettings): Promise<SrtInputNode>;

Parameters

Parameter Type Description

settings

SrtInputSettings

Configuration for the SRT input

Returns:

Promise<SrtInputNode>

Example [02_srt_to_webrtc.ts]

Subscribe to an SRT source and generate local WebRTC output from it

export async function main() {
  // Note how, other than the input line, this example and rtmp_to_webrtc
  // are identical.
  const norsk = await Norsk.connect();

  const input = await norsk.input.srt(srtInputSettings);
  const output = await norsk.output.whep({ id: "webrtc", ...webRtcServerConfig });

  output.subscribe([{ source: input, sourceSelector: selectAV }]);
  console.log(`WebRTC Player URL: ${output.playerUrl}`);
}

const srtInputSettings: SrtInputSettings = {
  id: "srtInput",
  host: "0.0.0.0",
  port: 5001,
  mode: "listener",
  sourceName: "camera1",
};

Run the following command to generate example input at url srt://127.0.0.1:5001?pkt_size=1316:

ffmpeg -v error -re -stream_loop -1 -i data/Weaving.ts  -vcodec copy -codec copy -f mpegts -flush_packets 0 'srt://127.0.0.1:5001?pkt_size=1316'

Example [04_srt_to_hls_passthrough.ts]

Package an SRT stream into LL-HLS

export async function main() {
  const norsk = await Norsk.connect();

  const input = await norsk.input.srt(srtInputSettings);

  // Receive an inbound stream and segment it as CMAF chunks for publication as HLS and DASH
  // Note that as this is passthrough we don't necessarily know the bitrate of the stream
  // for the HLS multi variant (master) playlist.  Here we just set them by hand in the CMAF Audio and CMAF
  // video segmenters.  Other examples show how you can measure bitrates and use that in the multi variant playlist.
  // If a transcode is happening (take a look at the various _to_ladder examples) then
  // each streams will have well known bitrates that automatically flow through the workflow
  // Note that from here on down, the code is identical to the code in srt_to_hls_passthrough
  // With Norsk you only need to describe the desired media flow - it takes care of the differences
  // between various input types.

  const audioOutput = await norsk.output.cmafAudio({ id: "audio", bitrate: 20_000, ...segmentSettings });
  const videoOutput = await norsk.output.cmafVideo({ id: "video", bitrate: 1_500_000, ...segmentSettings });
  const mvOutput = await norsk.output.cmafMultiVariant({ id: "multi-variant", playlistName: "multi-variant", destinations });

  mvOutput.subscribe([
    { source: audioOutput, sourceSelector: selectPlaylist },
    { source: videoOutput, sourceSelector: selectPlaylist },
  ]);

  audioOutput.subscribe([{ source: input, sourceSelector: selectAudio }]);
  videoOutput.subscribe([{ source: input, sourceSelector: selectVideo }]);

  console.log(`Multi variant playlist: ${mvOutput.url}`);
  audioOutput.url().then(logMediaPlaylist("audio"));
  videoOutput.url().then(logMediaPlaylist("video"));
}

const destinations: CmafDestinationSettings[] =
  [{ id: "local", type: "local", retentionPeriodSeconds: 10 }];

const segmentSettings: CmafOutputSettings = {
  partDurationSeconds: 1.0,
  segmentDurationSeconds: 4.0,
  destinations
};

const srtInputSettings: SrtInputSettings = {
  id: "srtInput",
  host: "0.0.0.0",
  port: 5001,
  mode: "listener",
  sourceName: "camera1",
};

function logMediaPlaylist(name: string): (url: string) => void {
  return (
    url => { console.log(`${name} playlistUrl: ${url}`); }
  );
}

Run the following command to generate example input at url srt://127.0.0.1:5001?pkt_size=1316:

ffmpeg -v error -re -stream_loop -1 -i data/InkDrop.ts  -vcodec copy -codec copy -f mpegts -flush_packets 0 'srt://127.0.0.1:5001?pkt_size=1316'

Find Examples

Search for examples using srt in our examples repo.