how to capture continuous Realtime progress stream of output (from ffmpeg) - powershell

Question

I am having trouble showing the progress of ffmpeg through my script. I compile my script to exe with ps2exe and ffmpeg output on standard error instead of outputting on standard out
So I used to pipe 1 option
my script.ps1 now is:
# $nb_of_frames= #some_int
& $ffmpeg_path -progress pipe:1 -i input.mp4 -c:v libx264 -pix_fmt yuv420p -crf 25 -preset fast -an output.mp4
then I compile it with ps2exe. (to reproduce you don't need the compile, just use the above command with pipe:1 directly in cmd or PowerShell you will get the same behavior)
Normally with ffmpeg you get a progress reporting (that is interactive), one line containing the information and it keeps getting updated as 1 single line without spamming the console with 100s of lines, it looks like this.
frame= 7468 fps=115 q=22.0 size= 40704kB time=00:05:10.91 bitrate=1072.5kbits/s speed= 4.8x
But this does not appear in the compiled version of my script, so after digging I added -progress pipe:1 to get the progress to appear on std out
Now I get a continuous output every second that looks like this:
frame=778
fps=310.36
stream_0_0_q=16.0
bitrate= 855.4kbits/s
total_size=3407872
progress=continue
...
frame=1092
fps=311.04
stream_0_0_q=19.0
bitrate= 699.5kbits/s
total_size=3932160
progress=continue
I would like to print some sort of updatable percentage out of this, I can compute a percentage easily if I can capture that frame number, but in this case, I don't know how to capture a real-time output like this and how to make my progress reporting update 1 single line of percentage in real-time (or some progress bar via symbols) instead of spamming on many lines
(or if there is a way to make the default progress of FFmpeg appear in the compiled version of my script that would work too)
edit: a suggestion based on the below answer
#use the following lines instead of write-progress if using with ps2exe
#$a=($frame * 100 / $maxFrames)
#$str = "#"*$a
#$str2 = "-"*(100-$a)
#Write-Host -NoNewLine "`r$a% complete | $str $str2|"
Thanks

Answer 1

Here is an example how to capture current frame number from ffmpeg output, calculate percentage and pass it to Write-Progress:
$maxFrames = 12345
& $ffmpeg_path -progress pipe:1 -i input.mp4 -c:v libx264 -pix_fmt yuv420p -crf 25 -preset fast -an output.mp4 |
Select-String 'frame=(\d+)' | ForEach-Object {
$frame = [int] $_.Matches.Groups[1].Value
Write-Progress -Activity 'ffmpeg' -Status 'Converting' -PercentComplete ($frame * 100 / $maxFrames)
}
Remarks:
Select-String parameter is a regular expression that captures the frame number by the group (\d+) (where \d means a digit and + requires at least one digit). See this Regex101 demo.
ForEach-Object runs the given script block for each match of Select-String. Here $_.Matches.Groups[1].Value extracts the matched value from the first RegEx group. Then we convert it to integer to be able to use it for calculations.
Finally calculate the percentage and pass it to Write-Progress.