Put the demos in the intended playback order in an FFconcat playlist, then give that list to FFmpeg’s concat demuxer. The order of the playlist’s file lines determines the sequence FFmpeg sends to YouTube. This works best when the source files have compatible streams, codecs, and time bases; use the concat filter instead when you need to re-encode mismatched files.
Make an ordered FFconcat playlist
Create a plain-text file named playlist.ffconcat in the directory from which you will run FFmpeg. Put the header first, then one file directive per demo. The lines play from top to bottom:
ffconcat version 1.0
file '01-introduction.mp4'
file '02-feature-demo.mp4'
file '03-wrap-up.mp4'Use paths relative to the playlist’s working directory when practical. Keep filenames and paths accurate, and avoid rearranging the lines unless you want to change playback order.
Check whether the concat demuxer fits your files
The concat demuxer joins inputs in sequence without itself re-encoding them. Its inputs need compatible stream layouts, codecs, and time bases. If your demos differ in ways that prevent clean concatenation, standardize or re-encode them first, or use FFmpeg’s concat filter. FFmpeg’s FAQ says the filter approach is recommended when re-encoding is needed: FFmpeg FAQ.
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The demuxer determines each file’s start time from the preceding file’s duration. Bad or inaccurate duration metadata can cause timing artifacts at transitions. The playlist’s duration directive can override a file’s duration when you know the correct value; see the FFmpeg concat demuxer documentation for syntax and constraints. This workflow is configuration-based; the command below is an example, not a tested guarantee of seamless transitions.
Send the sequence to YouTube Live with FFmpeg
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In YouTube Live Control Room, configure the stream and copy its server URL and stream key. YouTube’s encoder setup describes entering both values in the encoder: YouTube encoder setup.
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Keep the stream key private. Use the current URL and key shown for your YouTube stream; do not publish them in a script, command history, or shared logs.
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Run FFmpeg with the concat input options before the output options. Replace the placeholders with your actual destination URL and key, and use an output format and encoding settings appropriate to your files and YouTube’s current requirements:
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-safe 0permits paths the demuxer otherwise treats as unsafe; use it only when your list needs that syntax. For simple relative filenames, prefer safe paths and omit-safe 0if your installed FFmpeg accepts the list without it. -
Watch the live preview and stream health in Live Control Room. Confirm that the introduction appears first, followed by the other demos in playlist order.
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Choose output settings against YouTube’s current guidance
YouTube’s RTMP/RTMPS encoder recommendations list H.264, H.265, or AV1 video, up to 60 fps, constant bitrate (CBR), and a recommended two-second keyframe interval with four seconds as the stated maximum. Recommendations depend on codec, resolution, and frame rate, so do not copy a bitrate from a different output format. Check the current official table before setting your encoder: YouTube live encoder settings.
YouTube recommends RTMPS for encrypted transport through Google’s servers. Use the protocol and destination shown for your stream setup. The YouTube guidance says streams under 12 hours are automatically archived; it does not establish the same unconditional archive guarantee for longer streams. See YouTube live stream archiving.
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The wrong demo plays first: inspect the order of
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The order is right, but a transition jumps or has a timing artifact: check each source’s duration metadata and the compatibility of its streams. Correct duration information or use a
durationdirective when appropriate; if the files are incompatible, re-encode them consistently or use the concat filter. -
FFmpeg rejects the playlist or a file: confirm the playlist syntax, filename spelling, relative-path base, and that every listed file is accessible to the FFmpeg process. Consult the documentation for the FFmpeg build you have installed.
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YouTube does not show the stream: verify the current server URL and stream key in Live Control Room, then check the encoder settings and YouTube stream-health messages.
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YouTube reports unstable or unsupported output: compare the actual codec, resolution, frame rate, bitrate mode, and keyframe interval with the current official encoder table rather than assuming one bitrate fits every stream.
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