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To rotate prerecorded product demos in a YouTube Live stream from Windows, apply FFmpeg’s transpose filter for a 90-degree turn or its rotate filter for another angle, pace the file as a live input, encode to YouTube’s recommended live profile, and send the output to the RTMPS URL and stream key shown in YouTube Live Control Room. Test the full playlist and preview before going public: rotation, file compatibility, audio, and looping behavior depend on your footage and command.
What you need before you start
- A current FFmpeg Windows build from a trusted distributor, with
ffmpegavailable in Command Prompt or PowerShell. - The local product-demo videos you want to play, with their dimensions, frame rates, codecs, and audio tracks checked.
- A YouTube channel with access to Live Control Room, where you can create or select a stream and retrieve its stream URL and stream key.
- A reliable upload connection sized for the bitrate you choose.
The correct rotation, output dimensions, frame rate, and audio handling cannot be determined without inspecting the actual files. FFmpeg’s Windows builds can also differ in version and enabled features, so check your installed build with ffmpeg -version and validate commands against it.
Choose the rotation filter
Rotate by 90 degrees
Use transpose for a quarter-turn. For clockwise rotation, FFmpeg documents transpose=dir=clock; use transpose=dir=cclock for counterclockwise rotation. Inspect the footage and choose the direction that makes the product appear upright.
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Rotate by another angle
Use rotate=ANGLE for a general angle, with the angle expressed in radians. FFmpeg defines positive angles as clockwise and negative angles as counterclockwise. A non-quarter-turn can leave empty corners in the frame, so determine whether to keep the resulting canvas, add a background, or choose different output dimensions. The desired presentation depends on the clip and cannot be inferred from the word “rotate.” FFmpeg rotate filter documentation
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Prepare one video or a playlist
Inspect the input files
Check each file’s video dimensions, frame rate, video and audio codecs, and whether it has an audio stream. This determines whether files can be joined directly and what output profile is sensible. A playlist made from clips with different stream layouts or timestamps may need separate preparation; do not assume a concat list will make incompatible inputs seamless.
Pace and loop a single file
FFmpeg’s -re reads an input at its native frame rate, which is useful when sending a local file as a live feed. -stream_loop -1 requests infinite looping of an input. These options have different jobs: pacing controls playback speed, while looping repeats an input. Test the exact command and file to confirm that it runs continuously as intended. FFmpeg main options
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Build a multi-file list
For multiple files, FFmpeg’s concat demuxer reads a text file listing the inputs. Its safe-path option rejects unsafe paths by default; relative paths using portable characters are the simplest choice. If you need absolute Windows paths or filenames with spaces, follow the documented list-file syntax and test it rather than reflexively disabling safe mode. Confirm that the chosen loop construction repeats the entire sequence, not just one input. FFmpeg concat demuxer documentation
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Connect FFmpeg to YouTube Live
- Open YouTube Studio and go to Live Control Room. Create a stream or select the scheduled stream you intend to use.
- Copy the stream URL and stream key from that stream’s settings. Use the RTMPS endpoint supplied there; YouTube recommends RTMPS, which encrypts the connection. Do not substitute a URL copied from an unrelated tutorial.
- Keep the key private. YouTube says, “Stream keys are like your YouTube stream’s password and address.” Do not expose it in screenshots, public scripts, source control, or logs. If it is exposed, reset it in Live Control Room and update your encoder. YouTube: Manage live stream settings
Do not publish or run a command containing a real key. Configure the destination and key privately in your local command or a protected environment, and avoid sharing output that may reveal credentials. If an RTMPS connection fails with an SSL error, first recheck that you copied the RTMPS URL and that the installed FFmpeg build supports it. YouTube’s troubleshooting guidance also points to port 443 when the URL is correct but SSL errors persist. YouTube: Troubleshoot live stream errors
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Set a YouTube-compatible output profile
YouTube’s encoder guidance lists H.264 video, constant bitrate (CBR), AAC or MP3 audio, and a recommended two-second keyframe interval that must not exceed four seconds. Choose resolution and frame rate to suit the source, then select a bitrate your upload connection can sustain reliably. Run a speed test and leave headroom rather than setting the stream at the connection’s limit. YouTube transcodes live streams into multiple playback formats. YouTube: Live encoder settings, bitrates, and resolutions
There is no universal command that fits every product demo: it must account for the rotation direction, dimensions, frame rate, audio policy, input compatibility, installed FFmpeg build, and the stream’s actual RTMPS destination. Build and test those pieces with your own media rather than treating a generic command template as safe to paste.
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Test the stream before making it public
- Set up a private or unlisted test stream if that suits your event, and use demo footage with motion and audio representative of the planned broadcast.
- Start FFmpeg and check the Live Control Room preview for orientation, framing, transitions, and audio.
- Check stream health and watch the test long enough to verify that the file or playlist continues and the connection remains stable.
- For a scheduled stream, wait for the preview and select Go live when ready. Start and stop behavior can vary with stream settings such as auto-start and auto-stop.
- Keep monitoring during the event. YouTube’s encoder guide says streams under 12 hours are automatically archived; check the current settings and guidance for your stream. YouTube: Create a live stream with an encoder
Fix common rotation and streaming problems
| Symptom | Likely cause | What to check |
|---|---|---|
| The demo is still sideways or upside down | The selected direction does not match the source footage. | Inspect the actual output and try the opposite transpose direction. The filter does not infer the intended product framing from the filename or orientation metadata. |
| Portrait footage is cropped or has bars | Rotating changes the frame geometry, while the output canvas may have different dimensions. | Decide whether to preserve the portrait frame, fit it inside a landscape canvas, or crop to a chosen output. Choose dimensions based on the intended presentation. |
| The playlist ends instead of repeating | The looping option may apply to one input, not the entire concat construction. | Check how the exact input and concat arrangement handles repetition; test the full sequence from beginning to end. FFmpeg main options and concat demuxer documentation |
| The concat list errors or rejects a path | List-file syntax, stream incompatibility, or default safe-path validation. | Check quoting and paths against the concat documentation. Prefer relative paths with portable characters, and confirm the files have compatible streams. |
| YouTube reports a connection or SSL error | The endpoint may be RTMP instead of RTMPS, or the connection may be blocked or unsupported. | Copy the RTMPS URL from the correct stream settings, confirm FFmpeg supports it, and consult YouTube’s advice about port 443 if the URL is correct but SSL errors persist. YouTube troubleshooting |
| The stream key appears in a screenshot, script, or log | The credential has been disclosed. | Reset the key in Live Control Room and replace it in your private encoder configuration. YouTube stream settings |
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