Realtime time overlay with ffmpeg

Question

I'm using the following ffmpeg command to create an H.264 encoded MPEG transport stream from a single png file with a text overlay.

ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -vf drawtext="fontfile=monofonto.ttf: fontsize=96: box=1: [email protected]: boxborderw=5: fontcolor=white: x=(w-text_w)/2: y=(h-text_h)/2: text='MY OVERLAY'" -r 25 -vcodec libx264 -f mpegts udp://0.0.0.0:1234

This seems to be working well, but as it is static you cannot easily tell if the encode has stopped. I'd therefore also like to add a timecode overlay so that the image has some changing content.

It is important that the stream is generated from a single static frame as I want the stream to be absolutely continuous and not a looped pre-encoded TS file.

Is there any way to add this dynamic overlay using ffmpeg? (I'm currently thinking piping one stream into another but that seems a bit hacky)

I'm trying to do this on a linux (Ubuntu) platform.

Answer 1

Wow... ffmpeg never ceases to amaze.. it's built in!

ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -vf drawtext="fontfile=monofonto.ttf: fontsize=96: box=1: [email protected]: boxborderw=5: fontcolor=white: x=(w-text_w)/2: y=((h-text_h)/2)+((h-text_h)/4): text='%{gmtime\:%H\\\\\:%M\\\\\:%S}'" -r 25 -vcodec libx264 -f mpegts udp://127.0.0.1:1234

The important bit for the timecode being: text='%{gmtime\:%H\\\\\:%M\\\\\:%S}'

There is some crazy escaping in there to get the colons to display(in bash), but that is UTC/GMT time of day timecode burnt in... just need to figure out the syntax for multiple drawtext functions now and I'm all set...