⚙️ What is RTMP?
RTMP (Real-Time Messaging Protocol) is a standard method for sending video from external software into Crowdcast. If your tool supports RTMP output, you can use it to broadcast through Crowdcast.
✅ Supported Encoders
Crowdcast works with most encoders, including:
OBS Studio
Wirecast
vMix
Ecamm Live
ffmpeg
Restream
Streamyard
Encoders which require an amendment to the server URL
Vimeo
BoxCast
LiveU Solo HDMI
Note: Some encoders — such as BoxCast — may not support encrypted RTMP (RTMPS) streams. If you're experiencing issues, try updating the server URL by changing the prefix from:
rtmps://
to:
rtmp://
Be sure to check your encoder’s support documentation to confirm whether unencrypted RTMP is required or supported.
❌ Not supported: Elgato Game Capture, Blackmagic ATEM
RTMP Mode is a great option for incorporating advanced graphics or transitions, multi-camera or multi-mic setups, and extremely high-quality audio. Event types that might benefit from RTMP Studio include music concerts, hybrid events, or professional streams that connect to multiple endpoints.
With RTMP Mode, there is a video delay (latency) of 10-20 seconds similar to Facebook Live and Youtube Live. Your video will stream and record in HD to all devices. We highly recommend ensuring you have a backup recorded to your device in case the stream is interrupted, you can replace after your event ends.
If you are considering the use of RTMP Mode to add lower thirds, overlays, or intro/outro screens you should first check out our Studio to see if Crowdcast’s built-in features meet your needs without needing additional software.
🔌 How to Use RTMP Mode
Enter RTMP Mode:
Open your event and go to the More tab (bottom-left).
Select Use RTMP Mode.
Copy Your Stream Info:
You’ll see your Server URL and Stream Key.
These can be generated any time ahead of your event.
Paste them into your third-party streaming tool.
Stay on the RTMP Page:
Do not leave this screen after copying the stream codes.
Crowdcast will wait for the video feed.
Only click Start Streaming from your encoder when you're ready to go live.
Go Live via Your Encoder:
In your third-party software, start the stream (e.g., click Start Streaming in OBS).
Once Crowdcast detects a video signal, your session will automatically go live and begin recording.
🖥️ Example: Connecting OBS to RTMP Mode
OBS is one of the easiest tools to start with.
Set up your scenes and sources in OBS.
Go to OBS Settings → Stream.
Set Service to “Custom.”
Paste in the Server URL and Stream Key from Crowdcast.
Click Start Streaming.
Return to Crowdcast's RTMP screen and stay there until your stream starts.
Encoding software settings for the best viewing experience
By default, RTMP Mode will deliver the video at the same quality received from your encoder app or gear. Based on our experience, we strongly recommend the following encoding software settings for the best viewing experience:
Resolution: 1920 x 1080 (1080p)
Video bitrate: 2000 - 3000 kbps
Audio bitrate: 64 or 128 kbps
Frame rate (FPS): 30
Keyframe intervals: 2 seconds (do not use automatic keyframe intervals)
If your bitrate is within our recommendations, and you're still experiencing dropped frames, try lowering the bitrate by 100 - 500 kbps and run another test event. We do have a team of external specialists who can assist you with your setup if needed.
Important RTMP Notes
🔄 Do Not Disconnect Mid-Stream
Avoid stopping or disconnecting your encoder during a broadcast.
This may break your recording and interrupt playback for attendees.
🔑 Unique Stream Keys per Session
If you're using multi-session events, each session has its own stream key.
Don’t reuse old keys between sessions.
♻️ Resetting an RTMP Session Learn more here
If you reset an RTMP session, you will be able to continue streaming within the same session. This means:
You can use the same stream key.
You can go live again in that same session.
You do not need to move your audience over to a new event or create a new session.
🎬 Crowdcast Studio Features Are Unavailable
RTMP sessions do not support:
Crowdcast Studio
Live Clipping
Timestamps for Q&A
Audience Screenshare
Multi-guest mode
If you need these features, consider using Studio mode instead.
💾 Save a Backup Recording
We recommend enabling local recording in your encoder.
If something goes wrong (e.g., network drops), you can upload a recording after the event.
🚦 Streaming Bitrate & Throttling
RTMP bitrate target: 5 Mbps average (token bucket algorithm).
Short bursts above 5 Mbps are fine, but sustained overages may result in throttling.
Make sure you have a stable and fast internet connection.
If you’re struggling to stream consistently at 5 Mbps, contact us at [email protected].
📉 Quality Limits
Live streams: Capped at 3.5 Mbps for stability.
VOD (recorded replay): Saved at up to 5 Mbps for higher quality.
Crowdcast recordings are typically available to download at up to 1080p format, even if the original stream was broadcast in higher quality like 4K. Currently, Crowdcast does not support 4K video downloads, as recordings are optimized for smooth playback and manageable file sizes. If the session was streamed in HD, the download will still be clear, but capped at 1080p. Imports are also capped at 1080p.
🔊🎥 Why OBS Streams Can Lose Sync on RTMP
When streaming over RTMP, some hosts notice audio and video drift apart, especially during scene switches. This does not appear in local recordings, which use a smoother timeline. Live RTMP is more sensitive because it encodes and transmits in real time.
Causes
1. Scene Switching & Encoder Resets
Video sources may re-initialize, resetting their sync clock.
Streaming software may force keyframes or reset encoders during complex transitions.
2. RTMP Buffering & Latency
CPU/GPU spikes during scene changes can stall video frames.
Audio keeps flowing, so video falls behind.
3. Different Audio vs. Video Paths
Audio = near-zero latency path.
Video = render → encode → transport.
Scene changes can disrupt video while audio continues smoothly.
✅ Best Practices for Hosts
Audio Setup
Use global audio devices only (Settings → Audio).
Avoid adding audio directly in scenes.
Video Setup
Match Base & Output Resolution (e.g., 1920x1080).
Keep FPS consistent (30).
Keep all sources at the same resolution & FPS.
Sources & Scenes
Right-click sources → uncheck “Close when not visible.”
Don’t duplicate audio sources in scenes.
Transitions
Use Cut or Fade (100–300ms).
Avoid stingers and heavy animations.
Encoder Settings
Resolution: 1920 x 1080 (1080p)
Video bitrate: 2000 - 3000 kbps
Audio bitrate: 64 or 128 kbps
Frame rate (FPS): 30
Keyframe intervals: 2 seconds (do not use automatic keyframe intervals)
Encoder: Hardware (NVENC/AMD) if available.
Profile: High.
Turn off “Rescale Output.”
Performance Monitoring
Use OBS Stats to check CPU/GPU load.
Keep usage under 70% during scene switches.
🛠️ Step-by-Step Setup
Configure global audio devices in Settings → Audio.
Lock resolution & FPS across all scenes.
Keep sources active (don’t let OBS reload them).
Simplify transitions (Cut/Fade only).
Set encoder to hardware, CBR, keyframe = 2s.
Test scene switches in a private event before going live.
🚨 Emergency Fix During a Live Stream
Switch to another scene and back.
Restart virtual audio device if used.
Restart the stream (recording stays synced).
👉 Summary: Keep audio global, video consistent, sources active, and transitions simple to avoid live sync issues.
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