my $frametotal,$fwide,$fhigh;
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You need to enclose the list of variables in parentheses or my will only work on $frametotal.

my ( $frametotal, $fwide, $fhigh );
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    @vcmd=(@vcmd,"-vf","scale=min(1280\\,iw):-1");
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That is usually written as:

    push @vcmd, "-vf", "scale=min(1280\\,iw):-1";
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    if($a eq "progress") {
        my $pcent=$prog{"frame"}/$frametotal*100;
        my $hcent=int($pcent/2);
        my $bar="[".("#" x $hcent).(" " x (50-$hcent))." ] ";
        $bar .=sprintf("%.2f",$pcent)."% fps=".$prog{"fps"};
        print "\r$bar";
    }
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I would probably write that as:

    next if $x ne 'progress';
    my $pcent = $prog{ frame } / $frametotal * 100;
    printf '%s[%-50s ] %.2f%% fps=%s', "\r", '#' x int( $pcent / 2 ), 
+$pcent, $prog{ fps };
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