Dynamic text-overlay on live-stream using gst-launch-1.0

Nicolas Dufresne nicolas at ndufresne.ca
Sun Feb 26 22:46:13 UTC 2017


Le dimanche 26 février 2017 à 06:18 -0800, Adam Plocher a écrit :
> Hello, I apologize if I'm posting this in the wrong place. I've
> previously asked this on stackoverflow and never got a response: http
> ://stackoverflow.com/questions/42128804/polling-a-text-file-and-
> overlaying-the-result-in-gstreamer
> 
> I have a Raspberry Pi with a camera and I'm live streaming that back
> to another unit (it's for a baby monitor).  On the same Pi, I have a
> temperature sensor that is dumping the current temp to a file every 5
> seconds.
> 
> My question: Is it possible to somehow poll that txt file and update
> a text-overlay on the live stream based on the current contents of
> that file?

filsesrc does not have this feature unfortunatly. I believe using
fdsrc, you could:

  tail -f text.txt | gst-launch-1.0 fdsrc ! ...

Let me know if that is a good work-around. If you are writing an app,
this can be done with a pipe, or if you prefer, with appsrc.

> 
> I've tried using a filesrc and subparse, and it will grab it
> initially if I format the input text file properly, but it doesn't
> seem to update itself:
> 
> gst-launch-1.0 -v \
>     filesrc location=/home/pi/temp.txt ! subparse ! txt. rpicamsrc
> awb-mode=0 awb-gain-red=1 awb-gain-blue=2 rotation=0 bitrate=820000
> preview=false brightness=67 contrast=30 sharpness=40 \
>     ! video/x-h264,width=800,height=480,framerate=10/1 \
>     ! h264parse ! decodebin ! videoconvert ! clockoverlay shaded-
> background=true draw-shadow=true font-desc="Nimbus Mono" \
>     ! textoverlay name=txt shaded-background=yes \
>     ! omxh264enc control-rate=3 target-bitrate=850000 \
>     ! tcpserversink host=0.0.0.0 port=5555 sync=true
> 
> The input file looks like this:
> 1
> 00:00:00,000 --> 99:59:59,000
> 69 degrees
> Thank you!
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