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#!/usr/bin/env perl

# Copyright (c) 2012 Nicolas George

#

# 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

make_chlayout_test - produce a multichannel test file with the channels

clearly identified

=head1 SYNOPSIS

tools/make_chlayout_test I I

=head1 DESCRIPTION

This script uses B and B to produce a file with audio

channels clearly identified by their name. The resulting file can be used to

check that the layout and order of channels is correctly handled by a piece

of software, either a part of B or not.

I is a list of channels or channel layouts, separated by '+'.

I is a list of valid ffmpeg outout options, including the

output file.

Note that some output codecs or formats can not handle arbitrary channel

layout.

This script requires a B binary, either in the source tree or in the

search path; it must have the flite audio source enabled.

=head1 EXAMPLES

Check that the speakers are correctly plugged:

  tools/make_chlayout_test FL+FR -f alsa default

Produce a 5.1 FLAC file:

  tools/make_chlayout_test 5.1 surround.flac

=cut

use strict;

use warnings;

use Getopt::Long ":config" => "require_order";

use Pod::Usage;

GetOptions (

  "help|usage|?|h" => sub { pod2usage({ -verbose => 1, -exitval => 0 }) },

  "manpage|m"      => sub { pod2usage({ -verbose => 2, -exitval => 0 }) },

) and @ARGV >= 2 or pod2usage({ -verbose => 1, -exitval => 1 });

my $channels = shift @ARGV;

my @out_options = @ARGV;

my $ffmpeg = exists $ENV{FFMPEG} ? $ENV{FFMPEG} :

             $0 =~ /(.*)\// && -e "$1/../ffmpeg" ? "$1/../ffmpeg" :

             "ffmpeg";

my %channel_label_to_descr;

my %layout_to_channels;

{

  open my $stderr, ">&STDERR";

  open STDERR, ">", "/dev/null";

  open my $f, "-|", $ffmpeg, "-layouts" or die "$ffmpeg: $!\n";

  open STDERR, ">&", $stderr;

  while (<$f>) {

    chomp;

    next if /^NAME/ or /:$/ or /^$/; # skip headings

    my ($name, $descr) = split " ", $_, 2;

    next unless $descr;

    if ($descr =~ /^[[:upper:]]+(?:\+[[:upper:]]+)*$/) {

      $layout_to_channels{$name} = [ split /\+/, $descr ];

    } else {

      $channel_label_to_descr{$name} = $descr;

    }

  }

}

my @channels = map { @{$layout_to_channels{$_} // [$_]} } split /\+/, $channels;

my $layout = join "+", @channels;

my $graph = "";

my $concat_in = "";

for my $i (0 .. $#channels) {

  my $label = $channels[$i];

  my $descr = $channel_label_to_descr{$label}

    or die "Channel $label not found\n";

  $graph .= "flite=text='${descr}', aformat=channel_layouts=mono, " .

            "pan=${layout}:${label}=c0 [ch$i] ;\n";

  $concat_in .= "[ch$i] ";

}

$graph .= "${concat_in}concat=v=0:a=1:n=" . scalar(@channels);

exec $ffmpeg, "-f", "lavfi", "-i", $graph, @out_options

  or die "$ffmpeg: $!\n";