For a 24/7 YouTube stream, resize prerecorded video to a deliberate output canvas without stretching it, then set bitrate, frame rate, keyframes, audio and transport for YouTube’s current ingest guidance. FFmpeg’s -stream_loop -1 can repeat an input, but looping a file does not by itself keep a broadcast healthy: rehearse the full encode and monitor both FFmpeg and YouTube Live.
Choose the output size before writing the FFmpeg command
Start with the presentation you want viewers to receive, not a bitrate number. A 16:9 canvas such as 1920×1080 is a common target, but it is not automatically right for every source or every host. YouTube accepts live video up to 60 fps and transcodes incoming live streams into viewer formats, so your encoder’s output is an ingest feed—not a guarantee that viewers will receive that exact resolution.
Keep the source’s aspect ratio. If it does not match the canvas, choose deliberately between showing the complete image with padding (often bars) or filling the canvas while cropping part of the image. Do not force the source into the canvas by independently changing width and height; that distorts people, landscapes and documentary footage. FFmpeg’s -s option sets frame size and, as an output option, inserts a scale filter at the end of the relevant filter graph. Use the scale filter directly when you need to control where scaling occurs in a more complex graph. See FFmpeg’s documentation.
Fit with padding or fill by cropping
- Fit: preserve the complete frame and add padding to reach the chosen canvas. This avoids losing picture content, but the result may have bars.
- Fill: scale until the canvas is covered and crop the excess. This avoids bars, but removes part of the source image; check captions, faces and other important details near the edges.
The exact filter expression depends on source and target dimensions, pixel format, and whether you need deinterlacing or frame-rate conversion. There is no one filter string that is best for every file. Confirm filter options against the FFmpeg version installed on the streaming host, then inspect the encoded output’s actual dimensions and play it back before using it live.
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Set bitrate, frame rate and keyframes for YouTube ingest
Resolution and bitrate are different settings. Choose a bitrate from YouTube’s current encoder table for the codec, resolution and frame rate you intend to send; do not assume that a larger frame automatically needs a particular bitrate, or extrapolate from one entry to another. YouTube’s current guidance supports RTMP/RTMPS and recommends RTMPS; lists H.264, H.265/HEVC and AV1 video; allows frame rates up to 60 fps; and lists AAC or MP3 audio. Check its live encoder guidance before deployment because ingest recommendations can change.
| Setting | Practical choice | Current YouTube guidance |
|---|---|---|
| Video bitrate | Use the table entry matching your chosen codec, resolution and frame rate; leave enough stable upload capacity for the encoded stream. | YouTube Help recommends 10 Mbps for H.264 at 1080p30 and 4 Mbps for H.264 at 240p–720p30 (page accessed 2026). These are ingest recommendations, not guarantees of viewer quality. |
| Keyframe interval | Configure the encoder for a two-second interval where available. | YouTube recommends 2 seconds and says not to exceed 4 seconds. |
| Rate control | Use constant bitrate (CBR) for the YouTube ingest feed. | YouTube’s guidance recommends CBR. |
| Frame rate | Choose a supported output rate appropriate to the source and host. Avoid needless conversion if the source rate already suits the workflow. | Up to 60 fps is supported; use the bitrate row for the output rate selected. |
| Audio | Map an intentional audio source and verify it is present and audible in playback. | AAC or MP3 are listed. For stereo, YouTube lists 44.1 kHz and 128 Kbps. |
| Color for SDR | Keep the output’s color signaling consistent with the material and encoder configuration. | YouTube lists Rec. 709 and 8-bit for SDR. |
| Transport | Use RTMPS where your FFmpeg build and ingest endpoint support it. | YouTube supports RTMP/RTMPS and recommends RTMPS. |
Codec choice also depends on what your installed FFmpeg build and hardware can encode reliably. H.264 is a straightforward baseline for many workflows; the current bitrate figures above apply only to the H.264 settings specified, not to HEVC or AV1. Do not select a more demanding codec or output frame rate without checking encoding speed on the actual host.
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Loop a prerecorded file with FFmpeg
FFmpeg’s -stream_loop -1 option is used to repeat an input indefinitely. That addresses file repetition only. It does not guarantee a stable connection, sufficient encoding speed, or a healthy YouTube broadcast. The example below is a command shape, not a verified universal command: select the appropriate input, filter, encoder, audio mapping, bitrate and RTMPS destination for your file and installed FFmpeg version before running it.
ffmpeg -re -stream_loop -1 -i input.mp4 -f flv "rtmps://INGEST_SERVER/STREAM_KEY"Replace the bracketed options with a complete configuration and use the RTMPS ingest address and stream key supplied by YouTube. Treat the key like a password: do not publish it, share it, or leave it in a public script or log. This abbreviated command does not perform resizing on its own; add a suitable scale/pad or scale/crop filter and the chosen video and audio encoders. Verify the correct RTMPS URL format for the endpoint and FFmpeg build you use.
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Make the video and audio choices explicit
- Decide the output canvas and whether the full frame is padded or the edges are cropped; do not stretch.
- Select the encoder available on the host, then test that it sustains the intended output frame rate.
- Set CBR and a two-second keyframe interval, and choose bitrate from YouTube’s row for the selected codec, resolution and frame rate.
- Map the intended audio track deliberately. If the input has no usable audio, decide whether the stream should be silent or have a separate audio source rather than assuming a track exists.
- Use the output container and transport expected by your chosen YouTube ingest endpoint; YouTube recommends RTMPS.
FFmpeg option placement matters: input and output options apply in different contexts. Consult the documentation for the version you have installed, run a short representative encode, and inspect its output rather than treating the example as a copy-and-run recipe.
Rehearse before relying on a 24/7 broadcast
- Prepare representative media. Test the actual file or a segment that includes typical movement, scene changes and audio. Check for interlacing, unusual aspect ratio, missing audio, or content near frame edges that cropping could remove.
- Run the intended encode. Use the final canvas, frame rate, codec, bitrate, keyframe interval and audio mapping. Watch FFmpeg’s logs and reported encoding speed; a command that runs briefly is not evidence the host will keep up indefinitely.
- Check YouTube Live. Confirm the console receives the feed, review stream-health messages, and verify audio and picture. YouTube recommends testing with representative movement and audio and monitoring stream health during the event.
- Plan operations separately from looping. Decide who or what will notice a stopped process, dropped connection or unhealthy ingest and how it will be restarted. The loop option does not supply a production watchdog or uptime guarantee.
A 2022 FFmpeg-user archive question about FFmpeg 4.4 describes a looping attempt alongside high CPU use and loss of YouTube’s live indicator; it is one user’s report, not proof that looping itself causes either problem on current versions. A 2020 community reply also discusses checking the Live console and possible frame-rate or keyframe issues, but current platform requirements should come from YouTube’s current guidance, not an old forum post.
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Troubleshoot common failures
| Symptom | What to check | Practical next step |
|---|---|---|
| Image looks stretched or people appear unusually wide or narrow | Output width and height were forced to the canvas without preserving aspect ratio. | Use proportional scaling; choose padding to retain the full frame or cropping to fill the canvas, then inspect playback. |
| YouTube reports ingest or stream-health warnings | Bitrate, keyframe interval, codec, frame rate, transport and network stability. | Compare each setting with YouTube’s current table and guidance; test RTMPS and monitor the console. |
| Encoding falls behind or CPU use is high | Encoding speed for the selected codec, frame rate, scaling work and host capacity. | Rehearse on the intended host. Reduce processing demands or choose an encoder the host can sustain; no universal performance figure applies. |
| The video repeats but the live indicator disappears or the feed stops | Whether FFmpeg is still running, whether it is sending data, and whether YouTube reports a healthy feed. | Check logs and the Live console; handle process recovery and reconnection as separate operational requirements from file looping. |
| Picture arrives but audio is missing or wrong | Whether the input has an audio stream and whether the command maps and encodes the intended track. | Inspect the source streams, map the correct audio deliberately, and play back a short test encode. |
| Bars appear or important content is cut off | The source and output aspect ratios and the chosen fit-versus-fill behavior. | Use padding if the complete image matters; use cropping only after checking that the removed edges are expendable. |
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