#!/usr/bin/env perl
 
 # Copyright (c) 2007-2013 Stefano Sabatini
 #
 # This file is part of FFmpeg.
 #
 # FFmpeg is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
 # License as published by the Free Software Foundation; either
 # version 2.1 of the License, or (at your option) any later version.
 #
 # FFmpeg is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 # See the GNU Lesser General Public License for more details.
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 
 =head1 NAME
 
 plotframes - Plot video frame sizes using ffprobe and gnuplot
 
 =head1 SYNOPSIS
 
 plotframes [I<options>] [I<input>]
 
 =head1 DESCRIPTION
 
 plotframes reads a multimedia files with ffprobe, and plots the
 collected video sizes with gnuplot.
 
 =head1 OPTIONS
 
 =over 4
 
 =item B<--input|-i> I<infile>
 
 Specify multimedia file to read. This is the file passed to the
 ffprobe command. If not specified it is the first argument passed to
 the script.
 
 =item B<--help|--usage|-h|-?>
 
 Print a brief help message and exit.
 
 =item B<--manpage|-m>
 
 Print the man page.
 
 =item B<--output|-o> I<outfile>
 
 Set the name of the output used by gnuplot. If not specified no output
 is created. Must be used in conjunction with the B<terminal> option.
 
 =item B<--stream|--s> I<stream_specifier>
 
 Specify stream. The value must be a string containing a stream
 specifier. Default value is "v".
 
 =item B<--terminal|-t> I<terminal>
 
 Set the name of the terminal used by gnuplot. By default it is
 "x11". Must be used in conjunction with the B<output> option. Check
 the gnuplot manual for the valid values.
 
 =back
 
 =cut
 
 =head1 SEE ALSO
 
 ffprobe(1), gnuplot(1)
 
 =cut
 
 use warnings;
 use strict;
 
 use File::Temp;
 use JSON -support_by_pp;
 use Getopt::Long;
 use Pod::Usage;
 
 my $input = $ARGV[0];
 my $stream_specifier = "v";
 my $gnuplot_terminal = "x11";
 my $gnuplot_output;
 
 GetOptions (
     'input|i=s'      => \$input,
     'help|usage|?|h' => sub { pod2usage ( { -verbose => 1, -exitval => 0 }) },
     'manpage|m'      => sub { pod2usage ( { -verbose => 2, -exitval => 0 }) },
     'stream|s=s'     => \$stream_specifier,
     'terminal|t=s'   => \$gnuplot_terminal,
     'output|o=s'     => \$gnuplot_output,
     ) or pod2usage( { -message=> "Parsing error", -verbose => 1, -exitval => 1 });
 
 die "You must specify an input file\n" unless $input;
 
 # fetch data
 my @cmd = (qw{ffprobe -show_entries frame -select_streams}, $stream_specifier, "-of", "json", $input);
 print STDERR "Executing command: @cmd\n";
 my $json_struct;
 {
     open(FH, "-|", @cmd) or die "ffprobe command failed: $!\n";
     local $/;
     my $json_text = <FH>;
     close FH;
     die "ffprobe command failed" if $?;
     eval { $json_struct = decode_json($json_text); };
     die "JSON parsing error: $@\n" if $@;
 }
 
 # collect and print frame statistics per pict_type
 my %stats;
 my $frames = $json_struct->{frames};
 my $frame_count = 0;
 foreach my $frame (@{$frames}) {
     my $type = $frame->{pict_type};
     $frame->{count} = $frame_count++;
     if (not $stats{$type}) {
         $stats{$type}->{tmpfile} = File::Temp->new(SUFFIX => '.dat');
         my $fn = $stats{$type}->{tmpfile}->filename;
         open($stats{$type}->{fh}, ">", $fn) or die "Can't open $fn";
     }
 
     print { $stats{$type}->{fh} }
         "$frame->{count} ", $frame->{pkt_size} * 8 / 1000, "\n";
 }
 foreach (keys %stats) { close $stats{$_}->{fh}; }
 
 # write gnuplot script
 my %type_color_map = (
     "I" => "red",
     "P" => "green",
     "B" => "blue"
     );
 
 my $gnuplot_script_tmpfile = File::Temp->new(SUFFIX => '.gnuplot');
 my $fn = $gnuplot_script_tmpfile->filename;
 open(FH, ">", $fn) or die "Couldn't open $fn: $!";
 print FH << "EOF";
 set title "video frame sizes"
 set xlabel "frame time"
 set ylabel "frame size (Kbits)"
 set grid
 set terminal "$gnuplot_terminal"
 EOF
 
 print FH "set output \"$gnuplot_output\"\n" if $gnuplot_output;
 print FH "plot";
 my $sep = "";
 foreach my $type (keys %stats) {
     my $fn = $stats{$type}->{tmpfile}->filename;
     print FH "$sep\"$fn\" title \"$type frames\" with impulses";
     print FH " linecolor rgb \"$type_color_map{$type}\"" if $type_color_map{$type};
     $sep = ", ";
 }
 close FH;
 
 # launch gnuplot with the generated script
 system ("gnuplot", "--persist", $gnuplot_script_tmpfile->filename);