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Läsa information från en .avi-fil
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Kategori: Multimedia
Inlagt: 2005-05-09
Läst: 2473
Inlagt av: Staffan Berg
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Beskrivning |
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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