plotframes

#!/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);