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WHIP

Node.js

An output type that allows streaming video and audio from Smelter over WHIP.

Usage

whipOutputExample.tsx
import Smelter from "@swmansion/smelter-node";
import { View } from "@swmansion/smelter";


async function run() {
  const smelter = new Smelter();
  await smelter.init();
  await smelter.registerOutput("example", <View />, {
    type: "whip",
    endpointUrl: "https://example.com/whip",
    bearerToken: "<TOKEN>",
    video: {
      encoder: { type: "ffmpeg_h264" },
      resolution: { width: 1920, height: 1080 },
    }
  });
}
void run();

Reference

Type definitions 

type RegisterWhipOutput = {
  type: "whip";
  endpointUrl: string;
  bearerToken?: string;
  video?: WhipVideoOptions;
  audio?: WhipAudioOptions;
};

Parameters for an WHIP output stream from Smelter.

Properties

endpointUrl

The destination URL for sending media streams using the WHIP.

  • Type: string

bearerToken

Token used for authentication when connecting to the WHIP endpoint.

  • Type: string

video

Parameters of a video included in the WHIP stream.

audio

Parameters of an audio included in the WHIP stream.

WhipVideoOptions

Type definitions 

type WhipVideoOptions = {
  resolution: {
    width: number;
    height: number;
  };
  sendEosWhen?: OutputEndCondition;
  encoder: WhipVideoEncoderOptions;
};

Parameters for registering an output that sends composed video/audio as an WHIP stream.

Properties

resolution

Output resolution in pixels.

  • Type: { width: number; height: number;}

sendEosWhen

Condition for termination of the output stream based on the input streams states. If output includes both audio and video streams, then EOS needs to be sent for every type.

encoder

Video encoder options.

WhipVideoEncoderOptions

Type definitions 

type WhipVideoEncoderOptions = {
    type: "ffmpeg_h264";
    preset?:
      | "ultrafast"
      | "superfast"
      | "veryfast"
      | "faster"
      | "fast"
      | "medium"
      | "slow"
      | "slower"
      | "veryslow"
      | "placebo";
    ffmpegOptions?: Map<string, string>;
  }

Configuration for the video encoder, based on the selected codec.

Properties (type: “ffmpeg_h264”)

preset

Video output encoder preset. Visit FFmpeg docs to learn more.

  • Type: "ultrafast" | "superfast" | "veryfast" | "faster" | "fast" | "medium" | "slow" | "slower" | "veryslow" | "placebo"
  • Default value: fast
  • Supported values:
    • ultrafast
    • superfast
    • veryfast
    • faster
    • fast
    • medium
    • slow
    • slower
    • veryslow
    • placebo

ffmpegOptions

Raw FFmpeg encoder options. Visit FFmpeg docs to learn more.

  • Type: Map<string, string>

WhipAudioOptions

Type definitions 

type WhipAudioOptions = {
  mixingStrategy?: "sum_clip" | "sum_scale";
  sendEosWhen?: OutputEndCondition;
  encoder: WhipAudioEncoderOptions;
}

Parameters of an audio source included in the WHIP stream.

Properties

mixingStrategy

Specifies how audio should be mixed.

  • Type: "sum_clip" | "sum_scale"
  • Default value: "sum_clip"
  • Supported values:
    • sum_clip - First, the input samples are summed. If the result exceeds the i16 PCM range, it is clipped.
    • sum_scale - First, the input samples are summed. If the result exceeds the i16 PCM range, the summed samples are scaled down by a factor to fit within the range.

sendEosWhen

Condition for termination of the output stream based on the input streams states. If output includes both audio and video streams, then EOS needs to be sent for every type.

encoder

Audio encoder options.

WhipAudioEncoderOptions

Type definitions 

type WhipAudioEncoderOptions = {
    type: "opus";
    channels: "mono" | "stereo";
    preset?: "quality" | "voip" | "lowest_latency";
    sampleRate?: number
  }

Configuration for the audio encoder, based on the selected codec.

Properties(type: “opus”)

channels

Channels configuration

  • Type: "mono" | "stereo"
  • Supported values:
    • mono - Mono audio (single channel).
    • stereo - Stereo audio (two channels).

preset

Audio output encoder preset.

  • Type: "quality" | "voip" | "lowest_latency"
  • Default value: voip
  • Supported values:
    • quality - Recommended for broadcast and high-fidelity applications requiring decoded audio to maintain maximum fidelity to the input signal.
    • voip - Recommended for VoIP and videoconferencing applications, prioritizing listening quality and speech intelligibility.
    • lowest_latency - Recommended only when achieving the lowest possible latency is the highest priority.

sampleRate

Sample rate for audio encoder.

  • Type: number
  • Default value: 48000
  • Supported values: 8000, 16000, 24000, 48000.

OutputEndCondition

Type definitions 

type OutputEndCondition =
  | { anyOf: string[]; }
  | { allOf: string[]; }
  | { anyInput: boolean; }
  | { allInputs: boolean; };

Defines when the output stream should end based on the state of the input streams. Only one of the nested fields can be set at a time.

By default, the input stream is considered finished/ended when:

  • TCP connection was dropped/closed.
  • RTCP Goodbye packet (BYE) was received.
  • MP4 track has ended.
  • Input was unregistered already (or never registered).

Properties

anyOf

List of the input streams. The output stream will terminate if any stream in the list finishes.

  • Type: string[]

allOf

List of the input streams. The output stream will terminate when all streams in the list finish.

  • Type: string[]

anyInput

Terminate the output stream if any of the input streams end, including streams added after the output was registered. Notably, the output stream will not terminate if no inputs were ever connected.

  • Type: boolean

allInputs

Terminate the output stream only when all input streams have finished. Notably, the output stream will terminate if no inputs were ever connected.

  • Type: boolean