1

我正在尝试编写一个 Perl 代码来编辑 ID3V2 标签，即开始的艺术家名称，我可以寻找并阅读它，但是当我尝试编写新的时，它只是用新的艺术家名称替换文件的所有内容并损坏文件我我是新手，所以请给我一些指导，因为我不认为使用下面的库是我尝试过的代码。

#!/usr/bin/perl

use Fcntl qw( SEEK_SET );

my($fh, $filename, $byte_position, $byte_value);

$filename = $ARGV[0];

open(IN, "+>", $filename);
#open IN, $filename;

seek(IN,0,SEEK_SET);
read IN, $temp, 128;

print $temp;
print "\n";

seek(IN,14,SEEK_SET);
read IN, $temp, 16;
print "Artist is :" .$temp;
print "\n";


sysseek(IN,14,SEEK_SET);
#want to replace the Artist Name with new one.
syswrite (IN,$newArtist);

print "\n";

close(IN);
4

2 回答 2

1

您的open调用会截断文件。您需要使用打开文件+<而不是+>在不截断文件的情况下打开文件进行读写。

有关perldoc -f open更多信息，请参阅。

于 2014-03-19T12:00:17.823 回答
0

万一有人在这里寻找解决方案，有些东西对我有用。

my $myFile  = shift or die "Usage: <file.mp3> <artist> <title>\n";
my $newArtist   = shift or die "Usage: <file.mp3> <artist> <title>\n";
my $newTitle    = shift or die "Usage:<file.mp3> <artist> <title> \n";

#Pack data for artist name and title. creating frame of size 4byte.
my $artist_len = length($newArtist);
my $title_len = length($newTitle);
my $artist = pack('N',$artist_len);
my $title = pack('N',$title_len);

print"\n New artist name will be >>". $newArtist."\n";
print"\n New title will be >> ". $newTitle ."\n";

my $encoding = ":raw :bytes";
open myMP3, "+<$encoding",$myFile or die "Error!Can NOT open the MP3 file.\n";
open OUT_FILE, "+>$encoding", 'new.mp3' or die "Error!Can NOT open the file to write.\n";

my $length = 512;
read (myMP3, my $buffer, $length);
chomp($buffer);

#reading the first 10 bytes of the ID3v2 Header
my $tagheader = substr($buffer, 0, 10);
my ($IDtag, $version, $revision, $flags, $size) = unpack('A3 h h h N4',$tagheader);
print OUT_FILE $tagheader;

my $len = 0;
my $ptr1 = 0;
my $ptr2 = 0;

while(1)
{    
   #reading 10 bytes for each frame and adding 10 bytes for next frame  
    $ptr1 += 10+$len;
    $ptr2 = $ptr1+10;

   #reading header 
   #4bytes frame ID,
   #4bytes frame size
   #2bytes flags
    my $frameHeader = substr($buffer,$ptr1,10);
    my($frameID, $frameSize, $flag) = unpack('A4 N4 h2',$frameHeader);

    #TALB:album-name,TCON:content-type,TIT2:title,TPE1:Artist, TRCK:Track Number,TYER: year
    if (($frameID eq 'TALB') || ($frameID eq 'TCON') || ($frameID eq 'TIT2') || ($frameID eq  'TPE1') || ($frameID eq 'TRCK') || ($frameID eq  'TYER'))
    {

        my $readFrame = substr($buffer, $ptr2, $frameSize);
        my $myFrame = unpack('A*($frameSize)' ,$readFrame);
        if ($frameID eq "TPE1")
        {
                print OUT_FILE $frameID;
                print OUT_FILE $artist;
                print OUT_FILE $flag;
                print OUT_FILE $newArtist;
         }

        elsif ($frameID eq "TIT2") 
        {
                print OUT_FILE $frameID;
                print OUT_FILE $title;
                print OUT_FILE $flag;
                print OUT_FILE $newTitle;
        }

        else 
        {
            print OUT_FILE $frameHeader;
            print OUT_FILE $readFrame;
        }
    }
    else 
    {
         my $leng = length($buffer) - $ptr1;
         my $music = substr($buffer, $ptr1, $leng);
         print OUT_FILE $music;

         seek(myMP3 , 10 , 0);
         seek(OUT_FILE, 10 , 0);
         while(<OUT_FILE>)
         {
            print myMP3 $_;
         }
         unlink 'new.mp3';

        #close files
        close(myMP3);
        close(OUT_FILE);

        die "\n Update success!\n";

    }
    $len=$frameSize;
}
于 2017-01-21T19:02:57.170 回答