Audio Requirements for Social Platform Streaming
When multistreaming to social platforms through Castr, your stream must include both a video and an audio track. This article explains why, and how to handle common audio-related issues.
Why Do Social Platforms Require Audio?
Most social platforms — including YouTube, Facebook, and LinkedIn — require that incoming live streams contain both a video track and an audio track. Twitch is more tolerant and may accept video-only streams, but viewers will have no audio indicator and the experience will be degraded. If your stream is missing an audio track, platforms will typically either:
Reject the stream entirely (it won't go live)
Accept the stream but display an error on the viewer's side (e.g., YouTube shows "No audio data received")
This is a requirement set by the platforms themselves, not by Castr. Castr passes through whatever you send — so if your source has no audio, the destination platform may not accept it.
Streaming IP Cameras Without Audio
Many IP cameras and security cameras send video-only streams (no microphone). If you're trying to multistream an IP camera feed to YouTube or Facebook, you'll likely run into issues because those platforms expect an audio track.
Solutions:
Add a silent audio track: Configure your camera or encoder to include a silent AAC audio track. In OBS, you can add a silent audio source as a workaround
Use Castr's embed player instead: Castr's own player can handle video-only streams. If you embed the player on your website rather than streaming to social platforms, audio is not required
Use an encoder as a relay: Route the camera feed through OBS or vMix, add a silent audio source there, then send the combined stream to Castr
How to Add a Silent Audio Track in OBS
In OBS, go to Settings → Audio
Make sure at least one audio device is enabled (e.g., Desktop Audio or Mic/Auxiliary Audio)
If no microphone is connected, don't worry — OBS will still encode a silent AAC audio track as long as an audio device is enabled in Settings → Audio
Alternatively, add a Media Source with a silent audio file and loop it
The key is ensuring OBS outputs at least one audio track, even if it contains silence. This satisfies the platform's audio requirement.
Audio-Only Streaming with Castr
Castr supports audio-only streaming, but with limitations:
Works with Castr's embed player: You can send an audio-only stream to Castr and play it through the Castr player on your website
Does NOT work with social platforms: YouTube, Facebook, Twitch, and other social platforms require a video track. If you send audio-only to Castr and try to multistream it to these platforms, they will reject the stream
If you need to stream audio (e.g., a web radio) to YouTube, you'll need to combine your audio with a video element (a static image, looping video, or visualizer) using an encoder like OBS before sending it to Castr.
Audio Codec Best Practices
Codec: Use AAC (AAC-LC) for the audio codec. This is universally compatible with all platforms
Bitrate: 128 Kbps stereo is the standard for most streaming. For music-heavy content, 192–320 Kbps provides better quality
Sample rate: 48 kHz is the recommended standard for video streaming. 44.1 kHz (the CD/music standard) also works but 48 kHz is preferred
Channels: Stereo (2 channels). Mono works but stereo is preferred