To loop a 4K video into a YouTube Live broadcast, use FFmpeg’s -stream_loop -1 to repeat the file, -re to send it at normal playback speed, and an RTMPS destination with the stream URL and key from YouTube Live Control Room. The command below is a starting point for a 4K, 30 fps SDR file encoded as H.264; match the bitrate and keyframe interval to your chosen output settings.
Before you start
- Install an FFmpeg build that includes the encoder you plan to use. The example below requires
libx264. - Have a 4K video file ready and check its resolution, frame rate, audio, and whether it is SDR or HDR. The example assumes 30 fps, SDR video, and stereo audio.
- In YouTube Live Control Room, create or schedule a stream and copy its stream URL and stream key. Treat the key like a password: do not publish it, and reset it if it is exposed. See YouTube’s instructions for creating an encoder stream.
- Check that your sustained upload connection can carry the selected video and audio bitrate with headroom. A speed test is useful, but no single upload-speed figure guarantees a stable stream on every connection.
Choose 4K output settings
YouTube’s current encoder guidance gives different recommended video bitrates for 2160p according to frame rate and codec. These are ingest recommendations, not a promise that every viewer will receive 4K; YouTube processes live video into outputs, and playback quality depends on its processing and the viewer’s device and connection. The recommendations below are from YouTube’s encoder settings page, accessed in 2026.
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| Output | YouTube-recommended video bitrate |
|---|---|
| 2160p, 30 fps, AV1 or H.265/HEVC | 30 Mbps |
| 2160p, 30 fps, H.264 | 42 Mbps |
| 2160p, 60 fps, AV1 or H.265/HEVC | 35 Mbps |
| 2160p, 60 fps, H.264 | 50 Mbps |
The example uses H.264 at 30 fps, so its video bitrate is 42 Mbps. For a 60 fps output, use the row matching your codec instead. YouTube recommends CBR and a two-second keyframe interval, and says not to exceed four seconds. For HDR, YouTube recommends H.265; its guidance says AV1 is not supported for HDR. Check the current YouTube encoder settings for codec-specific details.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchAt 30 fps, a two-second GOP is 60 frames, hence -g 60 below. If you output at another frame rate, set GOP length to approximately twice that rate: for example, 120 frames at 60 fps. The example does not force a frame rate, scale the image, or set pixel format or color metadata. Inspect the file first and add conversion options only if the source and target require them.
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Get the YouTube RTMPS destination
- Open YouTube Live Control Room and create a new stream or open a scheduled stream.
- Copy the server URL and stream key shown for the stream. Use the RTMPS server information YouTube provides; do not paste your key into a public post, screenshot, or shared script.
- For a scheduled broadcast, start the encoder and wait for the preview in Live Control Room. Select Go live there when the preview and stream health are satisfactory. The exact controls can vary with the stream setup; YouTube documents stream settings at Manage live stream settings.
Start the prerecorded loop with FFmpeg
Replace input.mp4 with the file path and replace the RTMPS destination with the server URL and stream key from Live Control Room. Keep the destination private because it contains the key.
ffmpeg
-stream_loop -1 -re -i "input.mp4"
-c:v libx264 -preset veryfast
-b:v 42M -maxrate 42M -bufsize 84M
-g 60
-c:a aac -b:a 128k
-f flv "rtmps://SERVER/APP/STREAM_KEY"-stream_loop -1 repeats the input indefinitely; FFmpeg documents that option and its placement in the FFmpeg command documentation. It must appear before the input it applies to. -re is also before -i; it reads the file at its native playback rate rather than sending it as fast as the computer can process it. The output uses H.264, a constant target and maximum video bitrate, a two-second GOP for 30 fps, and AAC audio at 128 kbps.
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This is an illustrative command, not a tested universal recipe. FFmpeg’s RTMP/FLV output pattern is documented in FFmpeg Documentation (all); YouTube recommends RTMPS for a secure connection. Make sure the actual server address and key are exactly as YouTube gives them. If FFmpeg reports that libx264 is unavailable, install a build with that encoder or choose an encoder present in your build and use settings appropriate to it.
If your source is already compatible
You can try stream copying with -c copy instead of encoding when the source codecs, bitrate, keyframe spacing, frame rate, and container/ingest compatibility meet YouTube’s requirements. Copying avoids video re-encoding and can reduce CPU load, but it cannot change the encoded bitrate or keyframe spacing. FFmpeg describes copy as copying the stream without re-encoding in its command documentation.
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Test and monitor the broadcast
- Before a real event, run a private or otherwise appropriate test using the same file, motion, audio, encoder, and network conditions you expect to use. YouTube specifically advises testing with audio and movement similar to the intended stream.
- Watch the encoder preview and stream-health indicators in Live Control Room. Confirm the picture, audio, and incoming resolution look right before selecting Go live for a scheduled stream.
- Keep the FFmpeg process and the computer running for the entire broadcast. A local FFmpeg process depends on that computer, power, and network remaining available.
- For 4K, plan on normal latency: YouTube says the low-latency option is unavailable for 2160p streams.
Troubleshooting common problems
- FFmpeg exits with an encoder-not-found error: the installed build may not include
libx264. Use a build that does, or select an available encoder and adjust the command for it. - YouTube does not receive the stream: check that the server URL and stream key were copied correctly, the key has not been reset, and the destination uses the RTMPS details shown in Live Control Room. Never reveal the key while troubleshooting.
- The computer cannot encode smoothly: H.264 encoding at 4K is compute-intensive. Try an appropriate hardware or software encoder available in your FFmpeg build, or use compatible source streams with
-c copy; copying only works if the source already meets ingest requirements. - Stream health warns about bitrate or connection: compare your output with YouTube’s recommendation for the selected resolution, frame rate, and codec, then test sustained upload capacity with additional headroom. Network variation can cause trouble even when a brief speed test looks adequate.
- The loop is not 4K or the motion looks wrong: the command does not scale or force frame rate. Inspect the source and decide whether you need explicit scaling or frame-rate conversion; conversion can alter the image or motion and adds processing.
- The stream stops when you close a terminal or shut down: FFmpeg is running on your machine, so the process, power, and internet connection must stay available. For recovery, check the process, connection, and Live Control Room health before restarting with a valid key.
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