Stream audio only

The short version

YouTube won’t take a stream that carries only sound. Its list of live streaming errors includes “Please provide one video stream. The ingestion stream contains no video stream.” Twitch, Kick and Facebook don’t say what they do with a stream that has no video, and the settings pages they publish describe a video stream, so send them a picture too.

One still image is enough. Put your show art in an OBS scene with your microphone and music, lower the video bitrate to the smallest figure your platform publishes, and the rest of your upload goes to the sound.

Build the scene in OBS

These are OBS Studio’s own names (version 32).

• In Sources, click + and add an Image source, then choose your show art under Image File. Make it the size of your Base (Canvas) Resolution under Settings → Video, so it fills the picture without stretching. For several pictures in turn, use Image Slide Show instead.
• Your microphone comes in as the Mic/Auxiliary Audio device under Settings → Audio, or as an Audio Input Capture source in this scene. Music played on the computer comes in through Desktop Audio, or through application audio capture to take one app only.
• Leave the webcam out of the scene. Nothing else is needed for the picture.

Spend your upload on the sound, not the picture

These platforms ask for CBR, constant bitrate, so the encoder keeps sending the bitrate you set even when the picture never changes. A still image saves upload only if you lower Video Bitrate yourself, under Settings → Output. Set Output (Scaled) Resolution and Common FPS Values under Settings → Video to the platform’s lowest output:

• YouTube: 480p or 360p at 30 fps, from a published minimum of 400 kbps (H.264).
• Facebook: 360p, 400 to 1,000 kbps; its next row up, 480p at 30 fps, takes 600 to 2,000 kbps.
• Kick: at least 1,000 kbps, its lowest published figure.
• Twitch: its table lists nothing below 720p at 30 fps, 3,000 kbps.

On YouTube, 400 kbps of picture and 128 kbps of sound fit in 660 kbps of upload with the 20% headroom YouTube asks you to keep: less than 1 Mbps for the whole stream. The bandwidth calculator does the sum for your platform.

Leave Keyframe Interval at 2 seconds, even for a picture that never moves: Twitch, YouTube, Kick and Facebook all ask for 2. Choose Twitch, YouTube or Facebook Live from OBS’s own list under Settings → Stream and OBS sets it for you. Kick isn’t on that list, so it goes in as a custom server and OBS sets nothing: switch Output Mode to Advanced under Settings → Output and type 2 in Keyframe Interval (0=auto) on the Streaming tab; with an NVIDIA NVENC encoder that box reads Keyframe interval (seconds, 0 = auto).

To see that it took, start the stream, then open Help → Log Files → View Current Log. With the Software (x264) or NVIDIA NVENC encoder, the encoder’s settings in the log include a keyint: line counted in frames: 60 at 30 fps once 2 seconds is set, 250 if it was left at 0. AMD’s encoders print the same line in frames. Intel QuickSync and Apple VideoToolbox print it in seconds instead: keyint: 2 (Apple adds “(s)”), and 0 on QuickSync if the box was left at 0.

The sound: the platform sets the ceiling

With no picture to watch, viewers judge only the sound, so it is tempting to raise Audio Bitrate under Settings → Output. The platforms cap it: Twitch takes up to 160 kbps of AAC, Facebook up to 256 kbps (with Facebook Live picked from OBS’s list, OBS holds it at 128 unless you tick Ignore streaming service setting recommendations under Settings → Stream), and YouTube recommends 128 kbps, with a message in its error list when the audio bitrate is higher. Keep your sound in stereo, which all three take.

Listen before you go live

Check your voice in the microphone test, then record two minutes in OBS with the microphone and the music together and listen back on headphones. Check that the music doesn’t cover your voice and that your voice isn’t heard twice. If it is, see monitoring without echo.

Questions

Can I stream on YouTube with no video at all? No. YouTube’s error list asks for one video stream, so a still image is the smallest picture you can send.

Is this how a live podcast works? Yes, for a show with no cameras. With cameras, see the video podcast setup; for the microphones, the best podcast microphone guide.