How to send streamlink output into ffmpeg for further processing (ubuntu)?

[BosseB]

I have a script to download streaming videos where I use ffmpeg and in the process I have set up ffmpeg to scale the size into 480p and produce 30 fps video with keyframes on even seconds.

I cannot get ffmpeg to work for live streams on SVTPlay, but for that site I can use streamlink instead for the capture.

timeout --signal=2 $CAPTURETIME streamlink \"$URL\" 540p -o \"${TARGETFILE}\"

Here the timeout stops streamlink after the set time in $CAPTURETIME in seconds.

So now I want to send the streamlink output stream into ffmpeg as input so the output file will be written in the wanted format.

My ffmpeg based download command looks like this:

CMD="ffmpeg -hide_banner ${MODE} -i \"${M3U8URL}\" -r 30 -vf scale=w=-4:h=${VIDEORES} -c:v libx264 -preset fast -crf 26 -x264-params keyint=30:scenecut=0:open-gop=0 -c:a aac -t ${CAPTURETIME} ${TARGETFILE}"

where
$MODE and $M3U8URL are the source definition
$VIDEORES="480"
$CAPTURETIME=video cut in seconds
$TARGETFILE= output file name (mp4)

So I want streamlink hook into the stream and send it on as input to ffmpeg and observe the CAPTURETIME value (in seconds).

How can I do this? I am pretty new to streamlink and its help is overwhelmingly big...

[BosseB]

Reply to self:
This works fine on first test:

$ streamlink svt1-d.akamaized.net/se/svt1/manifest.mpd 540p --stdout | ffmpeg -i pipe:0 -r 30 -vf scale=w=-4:h=480 -c:v libx264 -preset fast -crf 26 -x264-params keyint=30:scenecut=0:open-gop=0 -c:a aac -t 120 streamtest_2_svt1.mp4

It gets a stream with 540p resolution (480 is not available) and converts it to a file with 480p resolution and 30fps and keyframes on even seconds to simplify any editing necessary (cut on even seconds, no artifacts).
The file size is 13 Mb for 2 minutes.

The only issue I have is that when ffmpeg stops processing, thanks to the -t 240 argument, it kills streamlink, which prints an error message:

error: Error when writing to output: [Errno 32] Broken pipe, exiting
[cli][info] Closing currently open stream...

So how can I make streamlink accept this without throwing an error?

UPDATE:
It really does not matter since the video is closed by ffmpeg and works perfectly.
Streamlink can say what it wants, it does not affect the final product.