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HLS

Node.js

An input type that allows Smelter to consume HLS playlists.

Usage

hlsInputExample.tsx
import Smelter from "@swmansion/smelter-node";


async function run() {
  const smelter = new Smelter();
  await smelter.init();
  await smelter.registerInput("example", {
      type: "hls",
      url: "https://example.com/playlist.m3u8"
  });
}
void run();

Reference

Type definitions 

type RegisterHlsInput = {
  type: "hls";
  url: string;
  required?: bool;
  offsetMs?: number;
  decoderMap?: DecoderMap;
  sideChannel?: SideChannel;
}

Parameters for registering an HLS input.

Properties

url

URL of the HLS playlist.

  • Type: string

required

Determines if the input stream is essential for output frame production. If set to true and the stream is delayed, Smelter will postpone output frames until the stream is received.

  • Type: boolean
  • Default value: false

offsetMs

Offset in milliseconds relative to the pipeline start (start request). If unspecified, the stream synchronizes based on the delivery time of the initial frames.

  • Type: number

decoderMap

Assigns which decoder should be used for media encoded with a specific codec.

sideChannel

Enable side channel publishing for this input. The external consumer reads decoded frames / audio from a Unix socket created under SMELTER_SIDE_CHANNEL_SOCKET_DIR.

DecoderMap

Maps codecs to the provided decoders.

Type definitions 

type DecoderMap = {
  h264?: 'ffmpeg_h264' | 'vulkan_h264';
};

Properties

h264

H264 decoder configuration.

  • Type: 'ffmpeg_h264' | 'vulkan_h264'
  • Default value: If available vulkan_h264 will be used, otherwise ffmpeg_h264
  • Supported values:
    • "ffmpeg_h264" - Software H264 decoder based on FFmpeg.
    • "vulkan_h264" (Required feature: gpu-video ) - Hardware decoder. Requires GPU that supports Vulkan Video decoding.

SideChannel

Per-track side channel configuration. See the Side Channel overview for details on how decoded data is exposed and consumed.

Type definition 

type SideChannel = {
  video?: boolean;
  audio?: boolean;
  delayMs?: number;
};

Properties

video

Publish decoded RGBA video frames for this input on the side channel.

  • Type: boolean
  • Default value: false

audio

Publish decoded PCM audio batches for this input on the side channel.

  • Type: boolean
  • Default value: false

delayMs

Side channel delay in milliseconds. Frames are buffered for this duration ahead of when the queue consumes them, so the side-channel subscriber receives them early and has roughly this much time to process before the frame is due.

  • Type: number
  • Default value: 0