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MP3 Player help required, problem with ID3 Tag!

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ianwuk

Technical User
Nov 3, 2003
1
GB
Hi,

I am working on a fairly basic MP3 player, and I have it so that it plays MP3 files and that it also brings up the information for the ID3 tag.

Unfortunately I cannot make it so that any new tag information is saved over the old tag, is there anyone out there kind enough to take a look at my program (see below) and provide a solution for me as it would be a big help.

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, Buttons, MPlayer, ComCtrls, ExtCtrls;

type
TForm1 = class(TForm)
mp3player: TMediaPlayer;
mp3List: TListBox;
btnOpenFolder: TBitBtn;
GroupBox1: TGroupBox;
edTitle: TEdit;
edArtist: TEdit;
edAlbum: TEdit;
edYear: TEdit;
edGenre: TEdit;
edComment: TEdit;
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
Label4: TLabel;
Label5: TLabel;
Label6: TLabel;
txtFolder: TStaticText;
Progress: TProgressBar;
ProgresTimer: TTimer;
procedure btnOpenFolderClick(Sender: TObject);
procedure mp3ListClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure ProgresTimerTimer(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

type
TID3Rec = packed record
Tag : array[0..2] of Char;
Title,
Artist,
Comment,
Album : array[0..29] of Char;
Year : array[0..3] of Char;
Genre : Byte;
end;

const
MaxID3Genre=147;
ID3Genre: array[0..MaxID3Genre] of string = (
'Blues', 'Classic Rock', 'Country', 'Dance', 'Disco', 'Funk', 'Grunge',
'Hip-Hop', 'Jazz', 'Metal', 'New Age', 'Oldies', 'Other', 'Pop', 'R&B',
'Rap', 'Reggae', 'Rock', 'Techno', 'Industrial', 'Alternative', 'Ska',
'Death Metal', 'Pranks', 'Soundtrack', 'Euro-Techno', 'Ambient',
'Trip-Hop', 'Vocal', 'Jazz+Funk', 'Fusion', 'Trance', 'Classical',
'Instrumental', 'Acid', 'House', 'Game', 'Sound Clip', 'Gospel',
'Noise', 'AlternRock', 'Bass', 'Soul', 'Punk', 'Space', 'Meditative',
'Instrumental Pop', 'Instrumental Rock', 'Ethnic', 'Gothic',
'Darkwave', 'Techno-Industrial', 'Electronic', 'Pop-Folk',
'Eurodance', 'Dream', 'Southern Rock', 'Comedy', 'Cult', 'Gangsta',
'Top 40', 'Christian Rap', 'Pop/Funk', 'Jungle', 'Native American',
'Cabaret', 'New Wave', 'Psychadelic', 'Rave', 'Showtunes', 'Trailer',
'Lo-Fi', 'Tribal', 'Acid Punk', 'Acid Jazz', 'Polka', 'Retro',
'Musical', 'Rock & Roll', 'Hard Rock', 'Folk', 'Folk-Rock',
'National Folk', 'Swing', 'Fast Fusion', 'Bebob', 'Latin', 'Revival',
'Celtic', 'Bluegrass', 'Avantgarde', 'Gothic Rock', 'Progressive Rock',
'Psychedelic Rock', 'Symphonic Rock', 'Slow Rock', 'Big Band',
'Chorus', 'Easy Listening', 'Acoustic', 'Humour', 'Speech', 'Chanson',
'Opera', 'Chamber Music', 'Sonata', 'Symphony', 'Booty Bass', 'Primus',
'Porn Groove', 'Satire', 'Slow Jam', 'Club', 'Tango', 'Samba',
'Folklore', 'Ballad', 'Power Ballad', 'Rhythmic Soul', 'Freestyle',
'Duet', 'Punk Rock', 'Drum Solo', 'Acapella', 'Euro-House', 'Dance Hall',
'Goa', 'Drum & Bass', 'Club-House', 'Hardcore', 'Terror', 'Indie',
'BritPop', 'Negerpunk', 'Polsk Punk', 'Beat', 'Christian Gangsta Rap',
'Heavy Metal', 'Black Metal', 'Crossover', 'Contemporary Christian',
'Christian Rock', 'Merengue', 'Salsa', 'Trash Metal', 'Anime', 'Jpop',
'Synthpop' {and probably more to come}
);

implementation

uses ShellAPI, ShlObj; // needed for the BrowseForFolder function

{$R *.DFM}

procedure FillID3TagInformation(mp3File:string; Title,Artist,Album,Year,Genre,Comment:TEdit);
var //fMP3: file of Byte;
ID3 : TID3Rec;
fmp3: TFileStream;
begin
fmp3:=TFileStream.Create(mp3File, fmOpenRead);
try
fmp3.position:=fmp3.size-128;
fmp3.Read(ID3,SizeOf(ID3));
finally
fmp3.free;
end;

{ or the non Stream approach - as in ChangeID3Tag procedure
try
AssignFile(fMP3, mp3File);
Reset(fMP3);
try
Seek(fMP3, FileSize(fMP3) - 128);
BlockRead(fMP3, ID3, SizeOf(ID3));
finally
end;
finally
CloseFile(fMP3);
end;
}
if ID3.Tag <> 'TAG' then begin
Title.Text:='Wrong or no ID3 tag information';
Artist.Text:='Wrong or no ID3 tag information';
Album.Text:='Wrong or no ID3 tag information';
Year.Text:='Wrong or no ID3 tag information';
Genre.Text:='Wrong or no ID3 tag information';
Comment.Text:='Wrong or no ID3 tag information';
end else begin
Title.Text:=ID3.Title;
Artist.Text:=ID3.Artist;
Album.Text:=ID3.Album;
Year.Text:=ID3.Year;
if ID3.Genre in [0..MaxID3Genre] then
Genre.Text:=ID3Genre[ID3.Genre]
else
Genre.Text:=IntToStr(ID3.Genre);
Comment.Text:=ID3.Comment
end;
end;


procedure ChangeID3Tag(NewID3: TID3Rec; mp3FileName: string);
var
fMP3: file of Byte;
OldID3 : TID3Rec;
begin
try
AssignFile(fMP3, mp3FileName);
Reset(fMP3);
try
Seek(fMP3, FileSize(fMP3) - 128);
BlockRead(fMP3, OldID3, SizeOf(OldID3));
if OldID3.Tag = 'TAG' then
{ Replace old tag }
Seek(fMP3, FileSize(fMP3) - 128)
else
{ Append tag to file because it doesn't exist }
Seek(fMP3, FileSize(fMP3));
BlockWrite(fMP3, NewID3, SizeOf(NewID3));
finally
end;
finally
CloseFile(fMP3);
end;
end;


procedure FillMP3FileList(Folder: string; sl: TStrings);
var Rec : TSearchRec;
begin
sl.Clear;
if SysUtils.FindFirst(Folder + '*.mp3', faAnyFile, Rec) = 0 then
try
repeat
sl.Add(Rec.Name);
until SysUtils.FindNext(Rec) <> 0;
finally
SysUtils.FindClose(Rec);
end;
end;

function BrowseDialog(const Title: string; const Flag: integer): string;
var
lpItemID : PItemIDList;
BrowseInfo : TBrowseInfo;
DisplayName : array[0..MAX_PATH] of char;
TempPath : array[0..MAX_PATH] of char;
begin
Result:='';
FillChar(BrowseInfo, sizeof(TBrowseInfo), #0);
with BrowseInfo do begin
hwndOwner := Application.Handle;
pszDisplayName := @DisplayName;
lpszTitle := PChar(Title);
ulFlags := Flag;
end;
lpItemID := SHBrowseForFolder(BrowseInfo);
if lpItemId <> nil then begin
SHGetPathFromIDList(lpItemID, TempPath);
Result := IncludeTrailingBackslash(TempPath);
GlobalFreePtr(lpItemID);
end;
end;


procedure TForm1.btnOpenFolderClick(Sender: TObject);
var mp3Folder : string;
begin

mp3Folder := BrowseDialog('Choose a folder with mp3 files', BIF_RETURNONLYFSDIRS);
if mp3Folder = '' then Exit;

txtFolder.Caption := mp3Folder;

//fill the list box with mp3 files
FillMP3FileList(mp3Folder, mp3List.Items);
end;

procedure TForm1.mp3ListClick(Sender: TObject);
var mp3File:string;
begin
if mp3List.Items.Count=0 then exit;
mp3File := Concat(txtFolder.Caption, mp3List.Items.Strings[mp3List.ItemIndex]);
if not FileExists(mp3File) then begin
ShowMessage('MP3 file '+#13#10+ mp3File +#13#10+'does not exist!');
exit;
end;

FillID3TagInformation(mp3File, edTitle, edArtist, edAlbum, edYear, edGenre, edComment);

Progress.Max:=0;

mp3player.Close;
mp3player.FileName:=mp3File;
mp3player.Open;

Progress.Max := mp3player.Length;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
txtFolder.Caption := ExtractFilePath(Application.ExeName);
FillMP3FileList(txtFolder.Caption, mp3List.Items);
Progress.Max:=0;
end;

procedure TForm1.ProgresTimerTimer(Sender: TObject);
begin
if Progress.Max<>0 then
Progress.Position := mp3player.Position;
end;

end.

Thank you for your time, I really appreciate it.
 
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