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Add FFmpeg’s drawtext video filter to overlay a clock on the video before it is encoded and sent to YouTube. Choose localtime to show the FFmpeg host’s configured local time, or gmtime to show UTC. The clock is burned into the outgoing picture, so the video must be filtered and encoded rather than passed through as stream-copy video.
Build the clock overlay
Here is a schematic filter value that displays the date and time in the top-left corner:
drawtext=fontfile=/path/to/font.ttf:text='%{localtime:%Y-%m-%d %H\:%M\:%S}':x=20:y=20:fontsize=32:fontcolor=white:box=1:boxcolor=black@0.55Replace /path/to/font.ttf with a font file that the FFmpeg process can access. The example requests white text, a partially transparent black box, a 32-pixel font, and a position 20 pixels from the left and top. These are example styling values, not tested settings for every resolution or shell.
FFmpeg documents clock expansions, text styling, and the drawtext filter in its filter reference. The exact escaping needed for colons and other punctuation depends on how the command is assembled: the shell, filtergraph, and any wrapper can each require escaping. FFmpeg’s documentation explains the multiple escaping layers and notes that using a text file can avoid some escaping problems. Test the exact command in the environment that will run the stream before leaving it unattended.
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Choose the time viewers should see
localtimedisplays the FFmpeg host’s configured local time. Use it when the display should follow that machine’s timezone.gmtimedisplays UTC. Choose it when viewers should share a single timezone-independent reference.- The example format,
%Y-%m-%d %H:%M:%S, includes the date and time. Adjust the format string if you want a time-only display.
This is a wall clock based on the host’s clock, not an elapsed time or timecode derived from the media’s presentation timestamp. The host’s clock must be accurate, and its timezone must be configured as intended if you use localtime. UTC avoids reliance on the host’s local timezone setting, but not on the host clock being correct.
Check FFmpeg and the font before streaming
The documented drawtext filter uses libfreetype; the current filter reference lists --enable-libfreetype and --enable-libharfbuzz as configure requirements. Supplying fontfile points the filter to a specific font. The font option and font fallback depend on additional fontconfig support, while text shaping depends on fribidi.
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- Digital alarm clock with a 0.7-inch green LED display for easily checking the time at a glance
- Built-in nightlight gently illuminates a dark room
- Repeating snooze function makes it possible to sleep a little longer
- AC powered with integrated power supply. Batteries may be used as a backup power source to ensure time and alarms are retained in memory for 8 hours (refer to User Manual for details)
- Measures 4.5 x 3.5 x 2.4 inches (LxWxH); weighs 0.4 pounds (6.6 oz) Note: Batteries are not included
Check the actual FFmpeg executable that will run the stream, rather than assuming an online example matches it. FFmpeg’s online documentation is regenerated nightly and advises consulting local documentation for older builds. Build options and installed libraries can differ between versions and distributions. See the FFmpeg documentation for documentation resources, and confirm that the target executable supports drawtext and the required libraries.
Integrate the filter into the YouTube command
- Start from the command that already works. Keep its actual input, output, audio mapping, protocol, codec, frame rate, and ingest settings in view; those depend on your stream setup.
- Add the video filter. For a straightforward video path, supply the filter with
-vf. For a more involved graph, use-filter_complexand connect the relevant video stream throughdrawtext. FFmpeg’s command-line documentation covers filtergraph usage and stream mapping. - Preserve audio deliberately. A video filter does not replace the need to map or otherwise handle the audio stream from your existing input. Check that the output still contains the audio you intend to send.
- Encode the filtered video. Because the overlay changes video frames, do not simply stream-copy already encoded video. Use an encoding path compatible with the rest of your command.
- Test the output before relying on it. Check that the clock updates, the date and time are correct, the font loads, the text is legible over changing footage, audio remains present, and the stream reaches YouTube as expected.
This guide does not prescribe a complete ingest command or numeric bitrate, resolution, frame-rate, or keyframe settings: those depend on the stream and should be checked against current YouTube guidance. A YouTube help page titled “Choose live encoder settings, bitrates, and resolutions” is available at YouTube Help; confirm current recommendations there rather than relying on unverified figures.
Rank #3
- Atomic Clock Digital - The clock has a built-in receiver that automatically synchronizes itself with WWVB radio broadcast, which will set and update time automatically every midnight, no need to set manually. It has four time zones selectable: EST, PST, MST, CST.
- Digital Wall Clock Battery Operated - This digital clock is supported by 3xAAA battery (Not included). No wires make it can be placed anywhere; and the low battery symbol reminds you to replace the battery in time to avoid getting the wrong time due to low power.
- Digital Wall Clock Large Display - The LCD screen measures 6.2 in x 3.7 in and it displays time, indoor temperature, day and date. Each section is showed separately, allows you to read the content easily and quickly.
- Atomic Clock with Auto DST - With DST on, the time would go forward or backward one hour automatically in daylight saving time, no worry about time changing on that day. If for no need, it could also be turned off, then “AUTO DST” disappears from screen.
- Digital Alarm Clock - The alarm could be turned on or off according to your need, just click the button to set. When alarm is set on, there is a bell icon staying on screen. The icon will disappear if alarm is set off. When alarm goes off, just click any button to stop it on the day.
Make the clock readable in a 24/7 stream
- Use a stable font path accessible to the account that runs FFmpeg, including after a restart.
- Keep the clock inside the visible safe area, away from important on-screen content and edges.
- Choose a size appropriate to the output resolution, and use a high-contrast color. A background box or border can help when footage behind the clock changes.
- For a long-running process, make the timezone choice explicit. Moving or rebuilding the host, or changing its configuration, can change what
localtimedisplays. - Verify the host clock independently; selecting UTC does not synchronize it.
Troubleshoot common clock problems
The filter is reported as unknown
The target FFmpeg build may lack drawtext or one of its required libraries. Check the local build and documentation, then use an executable built with the documented FreeType and HarfBuzz support.
The command fails around the time format
Colons and percent-based expansions may be interpreted at multiple levels. Adjust escaping for the shell and filtergraph actually in use, or use a text file where appropriate. Test the precise command in that environment.
Rank #4
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The font cannot be found
Confirm that the fontfile path exists and is readable by the process account. Use an absolute, stable path for a continuously running stream.
The displayed time or timezone is wrong
Check the host’s clock and timezone. Use gmtime if the desired display is UTC; use localtime only when the host’s configured local timezone is the intended one.
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- Large Digital Wall Clock with Big Numbers - Easy to Read: WallarGe digital wall clock has a high-definition LCD screen measures 14x6 inch and the time display is 8.1x4.3 inch, the large display helps you read the time from many angles at a room distance. You can also read the indoor temperature and date on screen for full information
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- Wall Mount Large Digital Clock with Fold-out Stand - Digital Clock for Wall or Desk: The clock comes with a mounting template ruler showing 8.7 inches distance between two mounting holes, so you don't need to measure holes on wall. If you intend it to be placed on desk with no holes on wall, you can just unfold the fold-out stand
- Wall Clock Large Display with AUTO DST: The clock will automatically adjust time in Daylight Saving Time with AUTO DST on. It has two time display modes (Military time and Standard time), just click 12/24 button to switch. And the alarm is optional, it can be turned off manually if for no need
The clock is hard to read
Change the position, size, text color, or background box using the filter options. Preview it over representative footage at the stream’s output resolution before leaving it running.
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