To loop one or more local videos continuously to YouTube Live with FFmpeg, put compatible files in an ffconcat playlist, loop that playlist with -stream_loop -1, and send a real-time encoded feed to the RTMPS URL and stream key from YouTube Live Control Room. The concat demuxer requires the files to have matching streams and time bases; if they do not, normalize or re-encode them before using this method.
What the concat demuxer does—and when to use it
FFmpeg’s concat demuxer reads a text playlist as a virtual input, presenting the listed files in sequence. With -stream_loop -1, FFmpeg repeats that input indefinitely; -re reads file input at its native rate so the output behaves like a live feed rather than sending the video as fast as the computer can process it. These are FFmpeg options, and exact syntax or encoder availability can vary by build. See the FFmpeg documentation and FFmpeg command-line documentation.
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This method is useful when you want to stream files in sequence without first creating one joined file. It is not a universal way to combine arbitrary videos: FFmpeg’s documentation says, “All files must have the same streams (same codecs, same time base, etc.).” If your sources differ, use a filter-based workflow that re-encodes them, or normalize them to compatible streams first. FFmpeg’s FAQ discusses the concat filter as an option when re-encoding is needed.
Prepare and check your video files
Confirm FFmpeg can produce the output
Install an FFmpeg build that includes the encoder and FLV muxer you intend to use. Check the build with:
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ffmpeg -versionIf you plan to use libx264, verify that encoder is available in your build. The example below uses H.264 video, AAC audio, and FLV output; it will not work unchanged if your FFmpeg build lacks those components.
Check that the files are compatible
Inspect each input with FFmpeg’s probing tools or another media inspector. Compare the streams present, codecs, time bases, dimensions, and frame rates. Files with mismatched stream layouts or timing may fail to concatenate cleanly or produce timestamp problems. Make the inputs compatible before starting the live broadcast.
For multiple files, list them in the order you want them to play. The concat demuxer relies on file duration information; inaccurate or truncated duration metadata can cause gaps, timestamp shifts, or artifacts at later boundaries. The demuxer supports a duration directive if you need to override a file’s stored duration; use an accurate value for the media.
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Create the ffconcat playlist
Save a UTF-8 plain-text file named, for example, playlist.ffconcat. Its first line must be exactly ffconcat version 1.0. Add one file directive for each video, in playback order:
ffconcat version 1.0
file '/path/to/first-video.mp4'
file '/path/to/second-video.mp4'Replace the sample paths with paths to your own files. Add or remove file lines as needed. Follow FFmpeg’s playlist syntax when escaping spaces and special characters in paths. The command below uses -safe 0 to permit paths outside the concat demuxer’s safe default syntax; use it only with a playlist you control, not a playlist containing untrusted paths.
Choose YouTube-compatible output settings
YouTube’s current encoder guidance supports RTMP or RTMPS ingest with H.264, HEVC, or AV1, frame rates up to 60 fps, AAC or MP3 audio, and constant bitrate (CBR). YouTube recommends keyframes every 2 seconds and says not to exceed 4 seconds. Bitrate depends on the codec, resolution, and frame rate, so choose it from the current YouTube encoder guidance for your actual output rather than copying a sample value.
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For one specific reference point, YouTube’s current table lists H.264 at 1080p30 as 5 Mbps minimum and 14 Mbps recommended. Those are encoder-setting recommendations, not independent performance findings; available upload capacity must sustain the feed. Recheck YouTube’s table when you configure a different resolution, frame rate, or codec.
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The GOP value in FFmpeg is measured in frames, while YouTube’s keyframe interval guidance is expressed in seconds. For a fixed-frame-rate output, calculate the GOP frame count as approximately the output frame rate multiplied by the interval in seconds. At 30 fps, a 2-second interval corresponds to 60 frames; at 60 fps it corresponds to 120. Choose settings that keep keyframes at the recommended cadence and no more than 4 seconds apart.
Start the looping stream
Copy the exact RTMPS server URL and stream key from YouTube Live Control Room. Substitute the URL and key in the final command argument below. Keep the key private: YouTube describes stream keys as “like your YouTube stream’s password and address.” Use the YouTube stream settings guidance and RTMPS guidance to locate and protect the credentials.
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ffmpeg -stream_loop -1 -re -f concat -safe 0 -i playlist.ffconcat
-c:v libx264 -preset veryfast -b:v 4500k -maxrate 4500k -bufsize 9000k
-g 60 -keyint_min 60 -sc_threshold 0
-c:a aac -b:a 128k -ar 44100
-f flv 'rtmps://STREAM_URL/STREAM_KEY'This is an illustrative H.264/AAC command, not a universal preset or a verified broadcast recipe. Its -g 60 setting represents a two-second GOP only at 30 fps. Adjust the GOP for your chosen output frame rate, and replace the example video bitrate with a value from YouTube’s current table. The -stream_loop, -re, and other input options appear before the corresponding -i, as required for input options.
Use the exact RTMPS URL provided in Live Control Room rather than assuming the sample URL structure. If you encounter a TLS connection error, YouTube’s RTMPS guidance recommends checking the RTMPS URL and port 443.
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Test and monitor the broadcast
- Enable live streaming in advance. YouTube says first-time live-stream enablement can take up to 24 hours. Check the channel’s eligibility and activation before the planned broadcast in its encoder setup guidance.
- Start FFmpeg and check YouTube’s preview. Confirm that video and audio appear, the order and loop boundaries are correct, and the stream-health messages do not show a problem.
- Test with representative content. YouTube recommends testing with audio and movement similar to what you will use during the actual stream. Allow time to catch connection, bitrate, and continuity issues before relying on the broadcast.
- Keep an eye on the live event. Check stream health and continuity while FFmpeg is running. The process depends on the computer, its storage, and its network connection remaining available.
YouTube’s encoder setup guidance says streams under 12 hours are automatically archived. Do not assume the same archive behavior for a broadcast that runs longer.
Troubleshoot common problems
- FFmpeg rejects a file or the playlist: Check that the first playlist line is exactly
ffconcat version 1.0, paths are valid, and the playlist syntax is correct. Confirm that the FFmpeg build supports the selected encoder and muxer. - The concat input fails or changes badly at a boundary: Compare the files’ streams, codecs, time bases, dimensions, and frame rates. The demuxer expects matching stream properties. Normalize the files or use a filter-based re-encode workflow.
- There is a gap, timestamp jump, or artifact: Check for inaccurate duration metadata or truncated input files. Correct the source durations; where appropriate, use the concat demuxer’s
durationdirective with an accurate value. - YouTube does not receive the stream: Verify the RTMPS URL and key copied from Live Control Room, check that the key has not been reset or mistyped, and confirm RTMPS connectivity. If TLS fails, check the exact URL and port 443 against YouTube’s RTMPS guidance.
- The picture buffers or quality is poor: Compare the configured video bitrate with YouTube’s table for the chosen codec, resolution, and frame rate. Check that the available upload rate can sustain the stream and review YouTube’s stream-health feedback.
- Keyframes arrive at the wrong interval: Recalculate the GOP in frames from the output frame rate. A GOP of 60 frames is two seconds only at 30 fps; the interval should follow YouTube’s 2-second recommendation and must not exceed 4 seconds.
- The broadcast stops when the computer or connection stops: This FFmpeg workflow runs from your own computer, so it depends on that machine, its files, and its internet connection staying available.
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