To connect Castr to Facebook Live with a custom RTMP URL, add Facebook as a Castr destination using Setup with Server/Key. Copy Facebook’s Server URL and Stream Key from Live Producer, paste them into Castr, start the Castr stream, then click Go Live manually in Facebook Live Producer.
The Facebook URL and key are destination credentials. They are not the source URL and key used by an encoder to send video into Castr. Keeping those two hand-offs separate is the main detail that prevents this setup from failing later.
What the custom RTMP route does
This route gives Castr the information needed to send an outgoing stream to Facebook. Facebook Live Producer supplies a server address and a stream key; Castr uses those values as the destination details for the Facebook broadcast.
The word “custom” describes the way the destination is connected, rather than a special Castr source. You are not creating a new Castr ingest key. You are taking Facebook’s destination credentials and entering them in the Facebook destination inside Castr.
There are therefore two possible video journeys:
- Your camera, encoder, playlist, or other source sends video into Castr using Castr’s source ingest URL and key.
- Castr sends that received video onwards to Facebook using Facebook’s Server URL and Stream Key.
Those credentials belong to different stages. If you put Facebook’s server URL into an encoder that is meant to feed Castr, the encoder is bypassing the intended source setup. If you put Castr’s ingest details into Facebook’s destination fields, Facebook cannot receive the broadcast.
The server/key route also has a timing detail that is easy to miss. Starting the stream in Castr makes the feed available, but it does not complete Facebook’s publication step automatically on this route. Once Castr is sending, return to Live Producer and choose Go Live.
Facebook’s interface can change, so use Facebook Live Producer to confirm the current labels and the account or Page selected before you publish. You should also check the current Facebook requirements for your account, destination and content rather than relying on an old tutorial.
Create or open a Castr livestream
Sign in to Castr and open the livestream project that will supply the video. If you do not have one yet, create a new livestream and complete the basic project setup first.
Before adding Facebook, decide what Castr will receive. It might be a live encoder feed, a prerecorded programme, a playlist, or another source supported by your Castr setup. The Facebook destination does not replace that source. It only gives Castr somewhere to send the stream after Castr has received it.
If you are preparing a long-running channel, test the source independently before adding another destination. A source that stops after a few minutes will still stop on Facebook, even when the server URL and key are correct. For a playlist-based workflow, the OBS and VLC video source playlist setup explains the separate job of keeping content available to the encoder.
Open the stream dashboard and look for the control used to add a platform or destination. Castr’s wording may vary slightly as its dashboard changes, but the relevant action is normally shown as Add destination or a similar platform-add control.
Do not start copying values yet. First make sure you are in the correct Castr livestream and that the intended source is attached to it. This prevents a common mistake where the Facebook destination is added to an empty test project while the real source continues elsewhere.
Add Facebook Live with Setup with Server/Key
In the Castr stream dashboard, add a destination and select Facebook Live. Castr may present more than one connection method. Choose Setup with Server/Key for this procedure.
The other main route is an account-linked or API connection, usually reached through an option such as Continue with Facebook. That is a different flow: it asks you to authorise a Facebook account rather than manually copy the server and key. It may be more convenient when it is available for the destination you need, but it does not use the custom RTMP fields described here.
The server/key route is useful when you want to see and control the exact Facebook credentials being handed to Castr. It also makes the two systems’ responsibilities clear. Facebook creates the destination details in Live Producer; Castr stores those details against the Facebook destination and sends the feed there.
Castr’s current guide says destination counts depend on the subscription plan. Its separate Facebook API guidance, published in 2024, described particular plan requirements for API integration and Pages. Those are not a reliable statement of the current offer, so check the plan information and the available destination controls in your Castr account before planning a multi-destination broadcast.
At this point, Castr should show fields for the streaming server and streaming key, or equivalent labels. Leave this Castr screen available while you open Facebook Live Producer in another tab. You will copy Facebook values into these fields shortly.
Find the Server URL and Stream Key in Live Producer
Open Facebook Live Producer for the profile, Page or other supported destination you intend to use. Confirm the destination before copying anything. A stream key is tied to the publishing context shown in the producer, and sending to the wrong destination can create a confusingly successful technical connection to the wrong place.
In the Live Stream Setup area, select Use Stream Key. Facebook should then show the destination information needed by an external streaming tool. Copy the Server URL and Stream Key exactly as displayed.
The Server URL is the address of the Facebook ingest service. The Stream Key is the credential that identifies and authorises the incoming broadcast for the selected Live Producer session. They work together, so do not copy a URL from one setup panel and a key from an unrelated session.
Facebook may offer a persistent stream key. A reusable key can reduce repeated setup work, but it also remains useful to anyone who obtains it. Keep it private, avoid placing it in screenshots or public notes, and replace or reset it if you believe it has been exposed.
Do not copy Facebook’s preview or viewing link into Castr. A viewing URL is for people watching the broadcast, while the Server URL is for a streaming application sending video. Likewise, the stream title and description are separate from the key.
For general background on how YouTube handles live encoders and stream keys, see YouTube’s live streaming help. The platform is different, but the distinction between an outgoing ingest destination and the programme information shown to viewers is useful when checking any live workflow.
Enter Facebook’s destination details in Castr
Return to the Facebook destination form in Castr. Paste Facebook’s Server URL into Castr’s Streaming Server field. Paste Facebook’s Stream Key into Castr’s Streaming Key field.
The mapping should be:
| Facebook Live Producer | Castr destination field |
|---|---|
| Server URL | Streaming Server |
| Stream Key | Streaming Key |
Check the first and last characters of both values after pasting. Avoid adding quotation marks, spaces or explanatory text. If your password manager or clipboard tool changes a value, type nothing manually until you have confirmed which characters were altered.
This is the destination side of the setup. Do not use Castr’s Stream Source Setup values here. Castr documents a separate source ingest URL and source key for an encoder sending video into Castr. Those values belong in the encoder’s output settings, not in the Facebook destination you are configuring now.
The distinction is easier to remember as “source into Castr, destination out to Facebook”. A camera or encoder uses the first set. Castr uses the second set. Facebook Live Producer provides the second set for this route.
Save or add the Facebook destination after the two fields are complete. If Castr reports that the destination cannot be added, first check the field mapping and whether the current Castr plan allows the destination count you are trying to use. A plan message and a credential error need different fixes.
Add stream details and confirm the source
Complete the stream details Castr requests, such as the title and description. Use wording that matches the broadcast viewers are about to see. If the content is devotional music, for example, state what the programme contains rather than leaving a temporary test title in place.
Select or attach the intended stream source. Depending on your workflow, that could be an existing source in the project or a source you configure separately. The source must produce an actual video feed before Facebook can receive a meaningful broadcast.
For an always-on channel, inspect the source over a longer test rather than judging it from the first few seconds. Check that the picture does not freeze, that audio is present where expected, and that the programme does not reach an end-of-file state. The guide to keeping a sleep sounds stream running overnight covers the operational questions that arise when a broadcast must continue beyond a normal viewing session.
You should also check the Facebook destination shown in the Castr dashboard. If your Facebook account can publish to more than one supported place, make sure the selected profile or Page is the one you want. Technical success does not correct a destination choice made earlier.
Save the completed destination and source configuration. At this stage, Facebook Live Producer should still be open with its setup panel, while Castr has the Facebook server and key stored against the stream. Neither side has necessarily published the broadcast yet.
Start Castr, then click Go Live in Producer
The order matters. First start the stream from Castr so that Castr begins sending the source feed to Facebook using the destination credentials.
Then return to Facebook Live Producer. Wait for Facebook to recognise or preview the incoming feed, and select Go Live manually. Castr’s documented server/key flow requires this step after the Castr stream starts. Castr does not automatically press Facebook’s publication control for you on this route.
This explains a common report that “Castr is streaming but Facebook is not live”. Castr can be sending the feed while Facebook is still waiting for the producer to approve publication. Starting one system is not the same as publishing in the other system.
After choosing Go Live, confirm the visible destination and the broadcast state in Facebook. Check the title, description, preview and audio before sharing the link. If the content is intended to run overnight, watch the beginning long enough to confirm that the feed is stable rather than assuming the hand-off completed because a preview appeared.
For channels that are meant to remain available continuously, the computer running the setup does not need to stay involved in the same way once the chosen workflow is operating. The important question is where the source and the forwarding process will continue. A cloud workflow such as StreamNeo removes the specific problem of leaving your own computer on to forward an uploaded video, but the publication step and destination rules still need to be checked separately.
If you are deciding between a hosted workflow and running the source yourself, compare the practical differences in cloud platforms for prerecorded YouTube livestreams. The relevant choice depends on whether you need local control, a source that must remain online, or a service that can keep a prepared file running without your home computer operating all night.
Troubleshoot the hand-off
Nothing reaches Castr. Check the encoder or source application first. It should use Castr’s source ingest URL and source key from the Stream Source Setup area. It should not use Facebook’s Server URL and Stream Key. If the encoder asks for a username and password in a Castr ingest workflow, Castr’s July 2026 guidance says to leave those fields empty; that instruction concerns source ingest, not the Facebook destination.
Castr shows activity but Facebook does not go live. Open Live Producer and choose Go Live manually. This is the defining extra step for the server/key route. If Facebook is showing no preview at all, return to the destination fields and compare the Server URL and Stream Key with the values currently shown in Live Producer.
The destination connection fails immediately. Check that Facebook’s Server URL went into Castr’s Streaming Server field and that Facebook’s Stream Key went into Streaming Key. Also check that neither value contains a leading or trailing space. If the key was regenerated in Facebook after you copied it, replace the old value in Castr.
Facebook publishes the wrong content or destination. Stop and check the selected Facebook profile or Page in Live Producer, then check which Castr source is attached to the project. A valid connection can still send the wrong programme if the project or destination was selected incorrectly.
The option is unavailable in Castr. Review the current Castr plan and the destination controls visible in your account. Castr says the number of destinations depends on subscription plan, while older Castr guidance about Facebook API availability was published in 2024 and may no longer describe every current plan.
You need to reuse a key. Use Facebook’s persistent-key option only if its security trade-off suits your workflow. Treat the key like a password, limit who can access it, and rotate it if it appears in a public document or shared screenshot.
A successful test should verify both sides: Castr is receiving the intended source and sending it to Facebook, and Facebook Live Producer has been told to publish the incoming feed. Checking only one dashboard leaves the final hand-off untested.
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FAQ
Where do I find the Facebook Live server URL and stream key?
Open Facebook Live Producer, choose the intended profile or Page, and select Use Stream Key in the setup area. Copy the displayed Server URL and Stream Key into Castr’s Streaming Server and Streaming Key fields.
Why do I have to click Go Live after starting Castr?
The server/key route sends the feed from Castr to Facebook, but Facebook still requires the publication action in Live Producer. Start Castr first, then return to Producer and click Go Live manually.
Is Facebook’s stream key the same as Castr’s source key?
No. Facebook’s key is a destination credential used by Castr when sending the broadcast to Facebook. Castr’s source key is used by an encoder or other source when sending video into Castr.
Can I use the Facebook API connection instead?
Castr documents an account-linked route using Continue with Facebook as an alternative to manually entering server and key values. Availability, supported destinations and plan requirements can change, so check the current options in Castr before choosing that route.