Use GStreamer’s tee element to fan out a shared capture pipeline into two queued branches: send one to splitmuxsink for sequential local recordings, and send the other through an FLV muxer to rtmpsink for YouTube. This is a pipeline design, not a universal copy-and-run command: the exact source, audio/video links, encoding chain and RTMP endpoint depend on your setup.
How the two-output pipeline works
The source and any processing that both outputs can share feed a tee. Put a queue immediately on each branch so recording and network output can run independently rather than blocking each other as readily.
- Recording branch:
queue→splitmuxsink, which creates sequential files. - YouTube branch:
queue→ stream-specific encoding or parsing →flvmux→rtmpsink.
The GStreamer Project describes tee as a one-to-many pipe fitting and splitmuxsink as a bin that muxes streams into files subject to time or size limits (tee documentation; splitmuxsink documentation). Its RTMP sink documentation demonstrates an FLV muxer upstream of rtmpsink (rtmpsink documentation).
Topology sketch
[source] ! [shared capture / conversion / encoding as appropriate] ! tee name=t
t. ! queue ! splitmuxsink location="record-%05d.mp4" max-size-time=<nanoseconds>
t. ! queue ! [stream-specific encode or parse chain] ! flvmux ! rtmpsink location="<YouTube RTMP URL and stream key>"This is schematic, not tested command-line syntax. A real pipeline may need separate audio and video paths, explicit linking or a different order of parsing and encoding. Confirm that the installed elements and chosen codecs negotiate compatible caps. The documentation does not establish one universally correct way to combine YouTube’s current server URL and key in rtmpsink’s location; follow the current encoder instructions in YouTube Studio and validate the endpoint locally. Never put a real stream key in published examples, source repositories or logs.
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Choose where encoding happens
The right placement depends on whether the local recording and YouTube output can use the same encoded streams.
Encode once before the tee
If both outputs can use the same codecs and encoded format, encoding before the tee can avoid duplicating encoder work. Ensure the downstream recording muxer and FLV muxer both accept the resulting streams.
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Branch before encoding
If the local files and live output need different codecs, resolutions or other encoding choices, branch earlier and use a separate encode chain on the live branch (or on both branches as needed). This adds workload; test CPU or GPU capacity and timing on the target machine.
Neither design is a universal winner. The trade-off depends on codec compatibility, the desired recording container and quality, available encoder headroom, storage throughput and the stability of the upload connection.
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Configure splitmuxsink for usable local files
splitmuxsink wraps a muxer and sink, beginning a new file when the mux contents approach a configured maximum size or time. For video, it splits at keyframe boundaries. It defaults to mp4mux and filesink, and those can be changed. It supports exactly one input video stream, with accompanying audio and subtitle streams, according to the GStreamer Project reference.
Set the file pattern and threshold
Use a location pattern such as record-%05d.mp4 to give successive files distinct names. Set max-size-time in nanoseconds or max-size-bytes in bytes; a value of zero disables that limit. Choose a threshold that suits your storage and expected segment lengths.
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Account for keyframes and closed GOPs
Video splits happen on keyframes, not at arbitrary exact instants. A segment can therefore exceed its nominal time or size threshold when the next keyframe is later; the minimum segment size is one GOP. For independently playable video segments, use closed GOPs. If predictable time-based boundaries matter, use a regular keyframe interval. The documented send-keyframe-requests property can request a keyframe at each time threshold, but it only works when max-size-bytes=0.
Consider asynchronous finalization only for a reason
With async-finalize=true, the old muxer/sink pair is detached to finish the preceding fragment while a new pair starts. In this mode, configure muxer-factory and sink-factory rather than direct muxer and sink object properties. This is an option to evaluate for the workload, not a guarantee that storage bottlenecks or other failures will disappear.
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Prepare YouTube before connecting the live branch
- Verify the channel and enable live streaming. YouTube Help says first-time activation can take at least 24 hours after the first request; enable it ahead of a scheduled test (YouTube Help: stream across platforms; page accessed 2026-10-03).
- In YouTube Studio’s current encoder workflow, obtain the RTMP server URL and stream key. The exact interface and endpoint details may change, so use the current instructions shown for your account.
- Supply the endpoint and key securely to the application or pipeline. Treat the key as a credential, and do not expose it in logs or shared code.
- Confirm the selected encoder and muxer produce streams accepted by
flvmux, and that the resulting FLV reachesrtmpsinkand connects to YouTube.
The cited official material does not prescribe one best codec, bitrate, resolution, frame rate, keyframe interval or audio profile for every channel and network. Set those for your source, encoder and available upload, then check YouTube’s current guidance and validate the complete stream.
Build and validate in stages
- Test capture and encoding alone. Check that expected audio and video are present, timestamps advance and output caps match what the next elements need.
- Add the recording branch. Let multiple segments complete. Open them, inspect timestamps and verify that split timing reflects the configured threshold and GOP boundaries.
- Add the queued live branch. Check FLV negotiation and confirm that the RTMP connection reaches YouTube using the current server URL and stream key.
- Run both branches together on the target machine. For a meaningful duration, watch for dropped buffers, encoder load, storage throughput, upload stability and GStreamer bus errors. Capacity requirements vary by workload; the official references provide no universal thresholds.
- Test shutdown and failure handling. Close the pipeline cleanly so the muxer can finalize the current file. Do not assume a forced process termination leaves the last segment complete and playable.
Common problems and fixes
| Symptom | Likely cause | What to check |
|---|---|---|
| A branch stalls or the other output is disrupted | Missing queues or downstream backpressure | Put a queue on each tee branch; inspect logs and buffer flow to identify which branch is falling behind. |
| Pipeline will not link or negotiate | Incompatible pads, caps, codecs or missing plugins | Check each element’s available pads and negotiated caps. Verify audio and video are linked into the appropriate muxers and that the required plugins are installed. |
| RTMP connection fails or YouTube receives no usable stream | Incorrect or stale server URL/key, unsupported FLV inputs, or a connection problem | Recheck the current YouTube encoder endpoint and key, verify the FLV chain, and inspect GStreamer errors without printing the secret key. |
| Segments are longer or larger than the configured limit | Splitting waits for a video keyframe; a GOP can exceed the threshold | Use a suitable regular keyframe interval; for time-driven requests, consider send-keyframe-requests with max-size-bytes=0. |
| Individual video segments do not play independently | GOPs are not closed, or the final file was not finalized | Configure closed GOPs for standalone segments and shut down the pipeline cleanly before relying on its last file. |
| Dropped buffers, recording gaps or unstable live output under combined load | Encoder, storage or upload capacity is insufficient for this workload | Measure each path separately, then together; reduce workload or adjust the design based on the bottleneck found. No single capacity figure applies to every source and machine. |
Or let it run in the cloud
If your goal is an always-on YouTube channel rather than capturing a live camera or building a GStreamer pipeline, StreamNeo is a separate option for looping uploaded videos from the cloud. Upload a recording or build a playlist, add your YouTube stream key once, and go live. Nothing has to stay powered on at home; it streams your upload as made, up to 4K 60fps at one flat price per slot, and automatically recovers if YouTube drops the stream. The first day is free with no card. Monthly pricing is $9.99 per month. It streams to YouTube and plays uploaded videos; it is not a camera-capture replacement. Start the free day on StreamNeo.
Quick Recap
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