RTMP client

Node.js Browser (Client)

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

Usage

rtmpClientOutputExample.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: 'rtmp_client',
    url: 'rtmp://example.com/rtmp',
    video: {
      encoder: {
        type: 'ffmpeg_h264',
        preset: 'ultrafast',
      },
      resolution: {
        width: 1920,
        height: 1080,
      },
    },
    audio: {
      channels: 'stereo',
      encoder: {
        type: 'aac',
      },
    },
  });
}
void run();

Reference

Type definitions

type RegisterRtmpClientOutput = {
  type: "rtmp_client";
  url: string;
  video?: VideoOptions;
  audio?: AudioOptions;
}

Properties

url

RTMP endpoint url.

• Type: string

---

video

Video track configuration.

• Type: VideoOptions

---

audio

Audio track configuration.

• Type: AudioOptions

VideoOptions

Type definitions

type VideoOptions = {
  resolution: {
    width: number;
    height: number;
  };
  sendEosWhen?: OutputEndCondition;
  encoder: VideoEncoderOptions;
}

Video track configuration options.

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.

• Type: OutputEndCondition

---

encoder

Video encoder options.

• Type: VideoEncoderOptions

VideoEncoderOptions

Type definitions

type VideoEncoderOptions =
  | {
      type: "ffmpeg_h264";
      preset:
        | "ultrafast"
        | "superfast"
        | "veryfast"
        | "faster"
        | "fast"
        | "medium"
        | "slow"
        | "slower"
        | "veryslow"
        | "placebo";
      pixelFormat?: "yuv420p" | "yuv422p" | "yuv444p";
      ffmpegOptions?: Record<string, string>;
    }
  | {
      type: "vulkan_h264";
      bitrate?: { averageBitrate: number; maxBitrate: number; } | number;
    };

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

---

pixelFormat

Encoder pixel format

• Type: "yuv420p" | "yuv422p" | "yuv444p"
• Default value: yuv420p
• Supported values:
  • yuv420p
  • yuv422p
  • yuv444p

---

ffmpegOptions

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

• Type: Record<string, string>

Properties (type: “vulkan_h264”) Required feature: vk-video

Hardware encoder. Requires GPU that supports Vulkan Video encoding.

bitrate

Encoding bitrate. If not provided, bitrate is calculated based on resolution and framerate. For example at 1080p 30 FPS the average bitrate is 5000 kbit/s and max bitrate is 6250 kbit/s.

Type definitions

type VulkanH264EncoderBitrate = { averageBitrate: number; maxBitrate: number; } | number;

Properties

averageBitrate

Average bitrate measured in bits/second. Encoder will try to keep the bitrate around the provided average, but may temporarily increase it to the provided max bitrate.

---

maxBitrate

Max bitrate measured in bits/second.

AudioOptions

Type definitions

type AudioOptions = {
  channels?: "mono" | "stereo";
  mixingStrategy?: "sum_clip" | "sum_scale";
  sendEosWhen?: OutputEndCondition;
  encoder: AudioEncoderOptions;
}

Parameters of an audio source included in the stream.

Properties

channels

Channels configuration

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

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.

• Type: OutputEndCondition

---

encoder

Audio encoder options.

• Type: AudioEncoderOptions

AudioEncoderOptions

Type definitions

type AudioEncoderOptions = {
  type: "aac";
  sampleRate?: number;
}

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

Properties(type: “aac”)

sampleRate

• Type: number
• Default value: 44100
• Supported values: 8000, 16000, 24000, 44100, 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