Script to cut video by silence part with FFMPEG - bash

Question

This is a question that is raised here How to split video or audio by silent parts or here How can I split an mp4 video with ffmpeg every time the volume is zero?
So I was able to come up with a straightforward bash script that works on my Mac.
Here it is (only argument is the name of the video to be cut, it will generate a file start_timestamps.txt with the list of silence starts if the file does not exist and reuse it otherwise):
#!/bin/bash
INPUT=$1
filename=$(basename -- "$INPUT")
extension="${filename##*.}"
filename="${filename%.*}"
SILENCE_DETECT="silence_detect_logs.txt"
TIMESTAMPS="start_timestamps.txt"
if [ ! -f $TIMESTAMPS ]; then
echo "Probing start timestamps"
ffmpeg -i "$INPUT" -af "silencedetect=n=-50dB:d=3" -f null - 2> "$SILENCE_DETECT"
cat "$SILENCE_DETECT"| grep "silence_start: [0-9.]*" -o| grep -E '[0-9]+(?:\.[0-9]*)?' -o > "$TIMESTAMPS"
fi
PREV=0.0
number=0
cat "$TIMESTAMPS"| ( while read ts
do
printf -v fname -- "$filename-%02d.$extension" "$(( ++number ))"
DURATION=$( bc <<< "$ts - $PREV")
ffmpeg -y -ss "$PREV" -i "$INPUT" -t "$DURATION" -c copy "$fname"
PREV=$ts
done
printf -v fname -- "$filename-%02d.$extension" "$(( ++number ))"
ffmpeg -y -ss "$PREV" -i "$INPUT" -c copy "$fname" )
Unfortunately it does not seem to work:
I have a video that is basically a collection of clips, each clip being introduced by a ~5 second silence with a static frame with a title on it. So I want to cut the original video so that each chunk is the 5 seconds "introduction" + video until the next introduction. Hope it's clear.
Anyway, in my script I first find all silence_start using ffmpeg silencedetect plugin. I get a start_timestamps.txt that read:
141.126
350.107
1016.07
etc.
Then for example I would call (I don't need to transcode again the video), knowing that (1016.07 - 350.107) = 665.963
ffmpeg -ss 350.107 -i Some_video.mp4 -t 665.963 -c copy "Some_video02.mp4"
The edge cases being the first chunk that has to go from 0 to 141.126 and the last chunk that has to go from last timestamp to end of the video.
Anyway the start_timestamps seem legit. But my output chunks are completely wrong. Sometimes the video does not even play anymore in Quicktime. I don't even have my static frame with the title in any of the videos...
Hope someone can help. Thanks.
EDIT Ok as explained in the comments, if I echo $PREV while commenting out the ffmpeg command I get a perfectly legit list of values:
0.0
141.126
350.107
1016.07
etc.
With the ffmpeg command I get:
0.0
141.126
50.107
016.07
etc.
bash variable changes in loop with ffmpeg shows why.
I just need to append < /dev/null to the ffmpeg command or add -nostdin argument. Thanks everybody.