// First, put a memo, button and a open dialog on an empty form.
// Then use the following code to show the information of a avi file.

unit Unit1;

interface

uses
 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
 StdCtrls;

type
 TForm1 = class(TForm)
 Button1: TButton;
 Memo1: TMemo;
 OpenDialog1: TOpenDialog;
 procedure Button1Click(Sender: TObject);
 private
 { Private declarations }
 public
 { Public declarations }
 procedure ReadAviInfo(FileName: string);

 end;

var
 Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.ReadAviInfo(FileName: string);
var
 iFileHandle: Integer; // File handle

 // Needed for positioning in the avi file
 Aviheadersize: integer;
 Vheadersize: integer;
 Aviheaderstart: integer;
 Vheaderstart: integer;
 Aheaderstart: integer;
 Astrhsize: integer;

 // Temporary values
 TempTest: String[5];
 TempSize: Integer;
 TempVcodec: String[5];
 TempAcodec: integer;
 TempMicrosec: integer;
 TempLengthInFrames: integer;
 TempAchannels: integer;
 TempAsamplerate: integer;
 TempAbitrate: integer;

 // Final values
 Size: double;
 Length: string;
 Vcodec: string;
 Vbitrate: double;
 VWidth: integer;
 VHeight: integer;
 Fps: double;

 LengthInSec: double;
 Acodec: string;
 Abitrate: string;
begin
 // Open the file
 iFileHandle := FileOpen(FileName, fmOpenRead);

 // Test to see if file is AVI
 FileSeek(iFileHandle, 7, 0);
 FileRead(iFileHandle, TempTest, 5);
 if copy(TempTest, 0, 4) <> 'AVI ' then
 begin
 MessageDlg('Could not open ' + FileName +
 ' because it is not a valid video file', mtError, [mbOk], 0);
 Exit;
 end;

 // File size
 FileSeek(iFileHandle,4,0);
 FileRead(iFileHandle, TempSize, 4);

 // Avi header size (needed to locate the audio part)
 FileSeek(iFileHandle,28,0);
 FileRead(iFileHandle, Aviheadersize, 4);

 // Avi header start (needed to locate the video part)
 Aviheaderstart := 32;

 // Microseconds (1000000 / TempMicrosec = fps)
 FileSeek(iFileHandle,Aviheaderstart,0);
 FileRead(iFileHandle, TempMicrosec, 4);

 // Length of movie in frames
 FileSeek(iFileHandle,Aviheaderstart + 16,0);
 FileRead(iFileHandle, TempLengthInFrames, 4);

 // Width
 FileSeek(iFileHandle,Aviheaderstart + 32,0);
 FileRead(iFileHandle, VWidth, 4);

 // Height
 FileSeek(iFileHandle,Aviheaderstart + 36,0);
 FileRead(iFileHandle, VHeight, 4);

 FileSeek(iFileHandle,Aviheaderstart + Aviheadersize + 4,0);
 FileRead(iFileHandle, Vheadersize, 4);

 Vheaderstart := Aviheaderstart + Aviheadersize + 20;

 // Video codec
 FileSeek(iFileHandle,Vheaderstart + 3,0);
 FileRead(iFileHandle, TempVCodec, 5);

 Aheaderstart := Vheaderstart + Vheadersize + 8;

 FileSeek(iFileHandle,Aheaderstart - 4,0);
 FileRead(iFileHandle, Astrhsize, 5);

 // Audio codec
 FileSeek(iFileHandle,Aheaderstart + Astrhsize + 8,0);
 FileRead(iFileHandle, TempACodec, 2);

 // Audio channels (1 = mono, 2 = stereo)
 FileSeek(iFileHandle,Aheaderstart + Astrhsize + 10,0);
 FileRead(iFileHandle, TempAchannels, 2);

 // Audio samplerate
 FileSeek(iFileHandle,Aheaderstart + Astrhsize + 12,0);
 FileRead(iFileHandle, TempAsamplerate, 4);

 // Audio bitrate
 FileSeek(iFileHandle,Aheaderstart + Astrhsize + 16,0);
 FileRead(iFileHandle, TempAbitrate, 4);

 // Close the file
 FileClose(iFileHandle);

 // Analyse the video codec (more can be added)
 Vcodec := copy(TempVcodec, 0, 4);
 if Vcodec = 'div2' then Vcodec := 'MS MPEG4 v2'
 else if Vcodec = 'DIV2' then Vcodec := 'MS MPEG4 v2'
 else if Vcodec = 'div3' then Vcodec := 'DivX;-) MPEG4 v3'
 else if Vcodec = 'DIV3' then Vcodec := 'DivX;-) MPEG4 v3'
 else if Vcodec = 'div4' then Vcodec := 'DivX;-) MPEG4 v4'
 else if Vcodec = 'DIV4' then Vcodec := 'DivX;-) MPEG4 v4'
 else if Vcodec = 'div5' then Vcodec := 'DivX;-) MPEG4 v5'
 else if Vcodec = 'DIV5' then Vcodec := 'DivX;-) MPEG4 v5'
 else if Vcodec = 'divx' then Vcodec := 'DivX 4'
 else if Vcodec = 'mp43' then Vcodec := 'Microcrap MPEG4 v3';

 // Analyse the audio codec (more can be added)
 case TempAcodec of
 0: Acodec := 'PCM';
 1: Acodec := 'PCM';
 85: Acodec := 'MPEG Layer 3';
 353: Acodec := 'DivX;-) Audio';
 8192: Acodec := 'AC3-Digital';
 else
 Acodec := 'Unknown (' + IntToStr(TempAcodec) + ')';
 end;

 case (Trunc(TempAbitrate / 1024 * 8)) of
 246..260: Abitrate := '128 Kbit/s';
 216..228: Abitrate := '128 Kbit/s';
 187..196: Abitrate := '128 Kbit/s';
 156..164: Abitrate := '128 Kbit/s';
 124..132: Abitrate := '128 Kbit/s';
 108..116: Abitrate := '128 Kbit/s';
 92..100: Abitrate := '128 Kbit/s';
 60..68: Abitrate := '128 Kbit/s';
 else
 Abitrate := FormatFloat('# Kbit/s', TempAbitrate / 1024 * 8);
 end;

 // Some final calculations
 Size := TempSize / 1024 / 1024;
 Fps := 1000000 / TempMicrosec; // FPS
 LengthInSec := TempLengthInFrames / fps; // Length in seconds
 Length := FormatFloat('# min', Int(LengthInSec / 60)) +
 FormatFloat(' # sec', Round(LengthInSec - (Int(LengthInSec / 60) * 60)));
 Vbitrate := (TempSize / LengthInSec - TempABitrate) / 1024 * 8;

 // Output information to memo field
 Memo1.Lines.Add('AVI INFORMATION');
 Memo1.lines.Add('Size: ' + FormatFloat('#.## MB',Size));
 Memo1.Lines.Add('Length: ' + Length);
 Memo1.Lines.Add('');
 Memo1.Lines.Add('VIDEO INFORMATION');
 Memo1.Lines.Add('Codec: ' + Vcodec);
 Memo1.Lines.Add('Bitrate: ' + FormatFloat('# Kbit/s', Vbitrate));
 Memo1.lines.Add('Width: ' + IntToStr(VWidth) + ' px');
 Memo1.lines.Add('Height: ' + IntToStr(VHeight) + ' px');
 Memo1.Lines.Add('FPS: ' + FormatFloat('#.##', fps));
 Memo1.Lines.Add('');
 Memo1.Lines.Add('AUDIO INFORMATION');
 Memo1.Lines.Add('Codec: ' + Acodec);
 Memo1.Lines.Add('Bitrate: ' + Abitrate);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 OpenDialog1.Filter := 'AVI files (*.avi)|*.avi';
 if OpenDialog1.Execute then
 begin
 Memo1.Clear;
 ReadAviInfo(OpenDialog1.FileName);
 end;
end;

end.