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    1 mp3info(1)                                                          mp3info(1)
    5 NAME
    6        mp3info - MP3 technical info viewer and ID3 tag editor
   10        mp3info [ -h | -G ]
   12        mp3info [-x] [-F] [-r a|m|v] [-p FORMAT_STRING] file...
   14        mp3info [-d] file...
   16        mp3info  [-i]  [-t title] [-a artist] [-l album] [-y year] [-c comment]
   17        [-n track] [-g genre] file...
   21        mp3info is a utility used to read and modify the ID3 tags in MPEG layer
   22        3  (MP3)  files.   It  can  also (optionally) display various technical
   23        attributes of the MP3 file.
   27        -a artist
   28               Specify ID3 artist name
   30        -c comment
   31               Specify ID3 comment
   33        -g genre
   34               Specify ID3 genre (use -G option for a list  of  valid  genres).
   35               You may specify either a genre name or a number.
   37        -l album
   38               Specify ID3 album name
   40        -n track
   41               Specify ID3 v1.1 track number
   43        -t title
   44               Specify ID3 track title
   46        -y year
   47               Specify ID3 copyright year
   49        -G     Display  a  list  of  valid  genres and their associated numeric
   50               codes. These are the only values accepted by the -g switch.
   52        -h     Display a help page
   54        -x     Display technical attributes of the MP3 file
   56        -r a|m|v
   57               Report bit rate of Variable Bit Rate (VBR) files as one  of  the
   58               following  (See  the  section  below entitled Bit Rates for more
   59               information):
   61               a - Average bit rate [float](Note: this option also  causes  the
   62                      bit  rates  of  non-VBR files to be displayed as floating
   63                      point values).
   64               m - Median bit rate [integer]
   65               v - Simply  use  the  word  'Variable'  [string]  (this  is  the
   66                      default).
   68        -i     Edit ID3 tag interactively (uses curses/ncurses functions)
   70        -d     Delete ID3 tag (if one exists)
   72        -f     Force  Mode: Treat all files as MP3s even if MP3 frames can't be
   73               found
   75        -F     Do a Full scan for technical information (see the section  Speed
   76               Considerations below for more information)
   78        -p "FORMAT_STRING"
   80               Print  MP3 attributes according to FORMAT_STRING.  FORMAT_STRING
   81               is similar to a printf(3) format string in that  it  is  printed
   82               verbatim   except  for  the  following  conversions  and  escape
   83               sequences. Any conversion specifier may optionally  include  the
   84               various alignment, precision, and field width modifiers accepted
   85               by printf(3).  See the EXAMPLES section below  for  examples  of
   86               how format strings are used in mp3info.
   89               Conversion Specifiers
   91                  %f     Filename without the path [string]
   92                  %F     Filename with the path [string]
   93                  %k     File size in KB [integer]
   94                  %a     Artist [string]
   95                  %c     Comment [string]
   96                  %g     Musical genre [string]
   97                  %G     Musical genre number [integer]
   98                  %l     Album name [string]
   99                  %n     Track [integer]
  100                  %t     Track Title [string]
  101                  %y     Year [string]
  102                  %C     Copyright flag [string]
  103                  %e     Emphasis [string]
  104                  %E     CRC Error protection [string]
  105                  %L     MPEG Layer [string]
  106                  %O     Original material flag [string]
  107                  %o     Stereo/mono mode [string]
  108                  %p     Padding [string]
  109                  %v     MPEG Version [float]
  110                  %u     Number of good audio frames [integer]
  111                  %b     Number of corrupt audio frames [integer]
  112                  %Q     Sampling frequency in Hz [integer]
  113                  %q     Sampling frequency in KHz [integer]
  114                  %r     Bit  Rate  in  KB/s  (type  and meaning affected by -r
  115                         option)
  116                  %m     Playing time: minutes only [integer]
  117                  %s     Playing time: seconds only [integer] (usually used  in
  118                         conjunction with %m)
  119                  %S     Total playing time in seconds [integer]
  120                  %%     A single percent sign
  122               Escape Sequences
  124                  \n     Newline
  125                  \t     Horizontal tab
  126                  \v     Vertical tab
  127                  \b     Backspace
  128                  \r     Carriage Return
  129                  \f     Form Feed
  130                  \a     Audible Alert (terminal bell)
  131                  \xhh   Any  arbitrary  character specified by the hexidecimal
  132                         number hh
  133                  \ooo   Any arbitrary character specified by the octal  number
  134                         ooo
  135                  \\     A single backslash character
  139 USAGE
  140        Specifying  MP3  files  without any other options displays the existing
  141        ID3 tag (if any).
  143        Specifying a track number of 0 reverts an ID3 tag to 1.0 format
  145        Non-specified ID3 fields, if existant, will remain unchanged.
  147        Genres can be specified as numbers or names: -g 17 same as -g Rock
  149        Multiple word fields must be enclosed in quotes (eg: -t "A title")
  152 NOTES
  153        Speed Considerations
  154               In order to  determine  certain  technical  attributes  (playing
  155               time, number of frames, number of bad frames, and in a few cases
  156               the bit rate) with absolute certainty, it would be necessary  to
  157               read  the  entire  MP3  file.   Mp3info  normally tries to speed
  158               things up by reading a handful of frames from various points  in
  159               the  file and estimating the statistics for the rest of the file
  160               based on those samples.  Usually, this results in very  accurate
  161               estimates.   Audio playing times are usually off by no more than
  162               a second, and the number of frames is off  by  less  than  0.1%.
  163               Often  the  estimates agree exactly with the full scans.  Never-
  164               theless, the user may wish to ensure that she is  getting  exact
  165               information.
  167               One  should  specify  the -F switch if one wants mp3info to read
  168               the entire MP3 file when  determining  this  information.   Note
  169               that  a  full  scan  will only affect mp3info's output if the -x
  170               switch is used or the -p switch is used with a  FORMAT_SPECIFIER
  171               containing  %m,  %s, %S, %u or (rarely) %r.  Using the -F switch
  172               under other conditions will only slow down mp3info.   Also  note
  173               that  a  FORMAT_SPECIFIER  containing  %b or a VBR MP3 file will
  174               automatically trigger a full scan even if the -F switch  is  not
  175               used.
  177               Several users have noted that the %u specifier used alone:
  180               mp3info -p "%u" song.mp3
  182               sometimes gives a different number of good frames than when used
  183               with the %b specifier:
  185               mp3info -p "%u %b" song.mp3
  187               This is because when you use %u by itself,  mp3info  only  esti-
  188               mates  the number of frames based on the bitrate and the size of
  189               the file.  When you use the %b specifier, you force  mp3info  to
  190               do a full scan of the file which guarantees an accurate count of
  191               both the good and bad frames.  If you want to guarantee an accu-
  192               rate count of the number of good frames when using %u by itself,
  193               you should use the -F option.
  196        Bit Rates
  197               MP3 files are made up of many (usally  several  thousand)  audio
  198               blocks  called  'frames'.   Each of these frames is encoded at a
  199               specific 'bit rate' which determines both  the  quality  of  the
  200               sound  and  the  size  of the frame itself.  Bit rates can range
  201               from 8 Kb/s (kilobits per second) to 320 Kb/s.   Note  that  the
  202               MP3  specification  only allows 14 discreet bit rates for an MP3
  203               file, so, for instance, a stereo MP3 could have frames with  bit
  204               rates of 128 Kb/s and 160 Kb/s, but nowhere in between.
  206               Audio  frames  with  high bit rates sound much better than those
  207               with lower bit rates, but take up more  space.   Obviously,  one
  208               would  like  to use a bit rate that is only high enough to main-
  209               tain a comfortable level of audio quality.   Normally,  all  the
  210               frames  in  an MP3 file are encoded at the same bit rate.  A few
  211               MP3 files, however, are encoded such that the bit rate may  vary
  212               from one frame to the next.  These MP3 files are called Variable
  213               Bit Rate (or VBR) files.   Since VBR files do not have one  sin-
  214               gle bit rate, attempting to report the bit rate of the file as a
  215               whole can be problematic.  Consequently, mp3info allows  you  to
  216               specify how you want this value reported.
  218               The default is to simply print the word 'Variable' where the bit
  219               rate would normally appear.  Another  option  is  to  print  the
  220               mathematical  average of all the frames.  This has the advantage
  221               of being completely accurate, but the  number  printed  may  not
  222               correspond  to  one  of  the 14 discreet bit rates that would be
  223               allowed for that file.  The third alternative solves that  prob-
  224               lem  by  allowing  the bit rate to be reported as the median bit
  225               rate which is what you would get if you lined up all the  frames
  226               in  the  file  by bit rate from lowest to highest and picked the
  227               frame closest to the middle of the line.
  229               For more specific usage information, see the -r switch  and  the
  230               %r  conversion  specifier  under  the  description  of -p's FOR-
  231               MAT_SPECIFIER.
  236        Display existing ID3 tag information (if any) in song.mp3
  239               mp3info song.mp3
  241        Set the  title,  author  and  genre  of  song.mp3.  (All  other  fields
  242        unchanged)
  244               mp3info -t "Song Title" -a Author -g "Rock & Roll" song.mp3
  246        Set  the  album field of all MP3 files in the current directory to "The
  247        White Album"
  250               mp3info -l "The White Album" *.mp3
  252        Delete the entire ID3 tag from song1.mp3 and song2.mp3
  254               mp3info -d song1.mp3 song2.mp3
  256        Delete the comment field from the ID3 tags of all MP3 files in the cur-
  257        rent directory. (All other fields unchanged)
  259               mp3info -c "" *.mp3
  261        Display the Title, Artist, Album, and Year of all MP3 files in the cur-
  262        rent directory.  We include the labels 'File', etc. and insert newlines
  263        (\n) to make things more readable for humans:
  265               mp3info  -p  "File:  %f\nTitle: %t\nArtist: %a\nAlbum: %l\nYear:
  266               %y\n\n" *.mp3
  268        Say you want to build a spreadsheet of your MP3 files.  Here's  a  com-
  269        mand  you might use to help you accomplish that.  Most spreadsheet pro-
  270        grams will import an ASCII file and treat a given character as a  field
  271        separator.   A commonly used field separator is the tab character.  For
  272        each MP3 file in the current directory, we want to output the filename,
  273        title, artist, and album on a single line and have the fields separated
  274        by a tab (\t) character.  Note that you must include a newline (\n)  at
  275        the end of the format string in order to get each file's information on
  276        a separate line.  Here's the command:
  278               mp3info -p "%f\t%t\t%a\t%l\t%y\n" *.mp3
  280        Some spreadsheets or other software may allow importing data from  flat
  281        files  where  each  field is a specific width.  Here's where the format
  282        modifers come into play.  This next command outputs the  same  informa-
  283        tion  as  the command above, but uses fixed-width fields instead of tab
  284        separators.  The filename field is defined as 50 characters  wide,  the
  285        title field is defined as 31 characters wide, and so on.
  287               mp3info -p "%50f%31t%31a%31l%4y\n" *.mp3
  289        The  problem  with  the  output of this command is that all strings are
  290        normally right- justified within their fields.  This looks a little odd
  291        since most western languages read from left to right.  In order to make
  292        the fields left-justified, add a minus sign (-) in front of the  field-
  293        width:
  295               mp3info -p "%-50f%-31t%-31a%-31l%-4y\n" *.mp3
  297        Now  suppose  you just want the running time of each MP3 file specified
  298        in minutes and seconds.  Simple enough:
  300               mp3info -p "%f: %m:%s\n" *.mp3
  302        You may notice when you do this, however, that leading  zeros  are  not
  303        displayed  in  the  seconds  field (%s).  So for instance, if you had a
  304        track four minutes and two seconds long its running time would be  dis-
  305        played  as '4:2' instead of '4:02'.  In order to tell mp3info to pad an
  306        integer field with zeros, you need to use a field  width  modifier  and
  307        place  a zero in front of it.  The following command is the same as the
  308        previous one, but it specifies that mp3info is to display  the  seconds
  309        field  with  a fixed field-width of two characters and to pad the field
  310        with leading zeros if necessary:
  312               mp3info -p "%f: %m:%02s\n" *.mp3
  314        The last trick we have to show  you  is  the  precision  specifier  for
  315        floating  point variables.  The following command displays the filename
  316        and average bit rate for all MP3 files in the current directory.
  318               mp3info -r a -p "%f %r\n" *.mp3
  320        By default, the floating point value of the average bit  rate  is  dis-
  321        played with six digits past the decimal point (ex: 175.654332).  If you
  322        are like me, this seems like a bit of overkill.  At most you  want  one
  323        or  two  digits  beyond  the decimal place displayed.  Or you might not
  324        want any.  The following command displays the  average  bit  rate  with
  325        first two, then zero digits beyond the decimal point:
  327               mp3info -r a -p "%f %.2r %.0r\n" *.mp3
  329        If  you wanted to specify a field width for a floating point value, you
  330        could do that by placing the field-width before the  decimal  point  in
  331        the field modifier.  This command does just that -- specifying an aver-
  332        age bit-rate field six characters wide that will  show  two  digits  of
  333        precision beyond the decimal point:
  335               mp3info -r a -p "%f %6.2r\n" *.mp3
  337 BUGS
  338        There's  no  "save  and quit" in interactive mode. You must fill in all
  339        the fields (even if it is with blanks) and let the  program  finish  by
  340        itself.  CTRL+C does leave MP3info, but the data isn't saved.
  342        Using  space  to erase tags in interactive mode does not work correctly
  343        if you then backspace over the deleted text.
  345        The title, author, album, and comment fields are limited to 30  charac-
  346        ters.  This is a limitation of the ID3 1.0 tag format, not MP3Info.  If
  347        you specify the track number (with the -n  switch),  the  ID3  1.0  tag
  348        becomes  a  1.1  tag and the comment field is limited to 28 characters.
  349        This is because the difference between ID3 1.0 and 1.1 is that the  tag
  350        number  is  stored  in  the last byte of the comment field.  This trick
  351        "borrows" two bytes from the  fixed-length  comment  field  effectively
  352        reducing the maximum comment by two characters.
  354        Genres  cannot be specified arbitrarily.  They must be specified from a
  355        pre-determined list (use mp3info -G to see that list).  Again, this  is
  356        a limitation of the ID3 1.0 tag format.
  358        Only ID3 versions 1.0 and 1.1 are supported.  ID3V2 is a much more pow-
  359        erful standard and is planned for some as-yet-undetermined future  ver-
  360        sion.  Unfortunately, a clean implementation is a heck of a lot of work
  361        and I'm unbelievably lazy, so don't hold your breath.  It  is  probably
  362        worth noting at this juncture, however, that I do accept patches.  :-)
  364        Exit codes are somewhat haphazard and not well documented.
  367 AUTHOR
  368        Cedric Tefft <cedric@phreaker.net>
  371 SEE ALSO
  372        printf(3)
  376 mp3info                        November 6, 2006                     mp3info(1)