[FFmpeg-user] metadata from concat list not working

[Goran Obal]

Hi.

I am trying to create a video from my music files, creating audio
visualization with showfreqs and displaying current filename with drawtext.

Here is my command:

ffmpeg -f concat -safe 0 -i files.txt -filter_complex
"[0:a]showfreqs=cmode=separate:colors=cyan|orange,drawtext=text='%{metadata\:title\:blah}':font=verdana:fontsize=56:fontcolor=white:x=(main_w/2-text_w/2):y=20[outv]"
-map [outv] -map 0:a -c:v h264_nvenc -c:a copy -pix_fmt yuv420p -shortest
video.mkv

And this is my files.txt:

file 'Alarm01.wav'
file_packet_metadata title=Alarm01
file 'Alarm02.wav'
file_packet_metadata title=Alarm02

Somehow this is not working for me and I don't understand why. My video
displays text "blah", which tells me that ffmpeg can't find the metadata...

I was also reading this: https://rensa.co/projects/ccrc-weather-station/
and they have done pretty much the same, only with pictures. And it worked
for them. I tried to reproduce what they have done - with pictures - but I
again don't get the metadata drawn...

Any help would be appreciated.

Kind regards.
Goran