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Läsa information från en .avi-fil
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Kategori: Multimedia
Inlagt: 2005-05-09
Läst: 2392
Inlagt av: Staffan Berg
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Beskrivning |
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I en avi-fil finns en massa information inbäddad, längd, storlek, avkodning m m. Med hjälp av detta kodexempel får du reda på det mesta av vad angiven avi-fil innehåller.
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Kod |
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.
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