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{*==============================================================================
Copyright (C) 2002, All rights reserved, Com-N-Sense Ltd
================================================================================
File: WaveFileParser.pas
Author: Liran Shahar, Com-N-Sense Ltd
Updated: 24/03/2002
Purpose: Parsing wave file into chunks
================================================================================
24/03/2002, Liran Shahar
- Initial release.
==============================================================================*}
unit WaveFileParser;
interface
uses
Sysutils, Classes;
type
TChunkType = array[1..4] of char;
PChunk = ^TChunk;
TChunk = packed record
cType: TChunkType;
dwSize: cardinal;
pData: pointer;
end;
TcnsWaveFileParser = class(TPersistent)
private
FFilename: AnsiString;
Chunks: TList;
protected
procedure SetFilename(AFilename: AnsiString); virtual;
function GetChunksCount: integer; virtual;
function GetChunk(Index: integer): PChunk; virtual;
procedure ProcessFile; virtual;
procedure ClearChunks; virtual;
public
constructor Create; virtual;
destructor Destroy; override;
function GetChunkByType(ChunkType: TChunkType): PChunk; virtual;
property Filename: AnsiString read FFilename write SetFilename;
property ChunksCount: integer read GetChunksCount;
property Chunk[Index: integer]: PChunk read GetChunk;
end;
implementation
const
RIFF_SIGNATURE = 'RIFF';
WAVE_SIGNATURE = 'WAVE';
type
TRIFFHeader = packed record
cSignature: TChunkType;
dwSize: cardinal;
cType: TChunkType;
end;
constructor TcnsWaveFileParser.Create;
begin
inherited Create;
FFilename := '';
Chunks := TList.Create;
end;
destructor TcnsWaveFileParser.Destroy;
begin
ClearChunks;
inherited Destroy;
end;
procedure TcnsWaveFileParser.SetFilename(AFilename: AnsiString);
begin
if FFilename <> AFilename then
begin
ClearChunks;
FFilename := AFilename;
ProcessFile;
end; // if
end;
function TcnsWaveFileParser.GetChunksCount: integer;
begin
Result := Chunks.Count;
end;
function TcnsWaveFileParser.GetChunk(Index: integer): PChunk;
begin
Result := nil;
if (Index > -1) and (Index < Chunks.Count) then
Result := Chunks[Index];
end;
procedure TcnsWaveFileParser.ProcessFile;
var
WaveFile: TFileStream;
Header: TRIFFHeader;
Chunk: PChunk;
begin
try
WaveFile := TFileStream.Create(FFilename, fmOpenRead + fmShareDenyWrite);
WaveFile.Read(Header, sizeof(Header));
if (AnsiCompareText(Header.cSignature, RIFF_SIGNATURE) = 0) and
(AnsiCompareText(Header.cType, WAVE_SIGNATURE) = 0) then
begin
while WaveFile.Position < WaveFile.Size do
begin
Chunk := AllocMem(sizeof(TChunk));
with Chunk^ do
begin
WaveFile.Read(cType, sizeof(cType));
WaveFile.Read(dwSize, sizeof(dwSize));
pData := AllocMem(dwSize);
WaveFile.Read(pData^, dwSize);
end; // with
Chunks.Add(Chunk);
end; // while
end; // if
finally
FreeAndNil(WaveFile);
end;
end;
procedure TcnsWaveFileParser.ClearChunks;
var
Chunk: PChunk;
begin
while Chunks.Count > 0 do
begin
Chunk := Chunks[0];
Chunks.Delete(0);
if assigned(Chunk^.pData) then
FreeMem(Chunk^.pData);
dispose(Chunk);
end; // while
end;
function TcnsWaveFileParser.GetChunkByType(ChunkType: TChunkType): PChunk;
var
iIndex: integer;
begin
Result := nil;
iIndex := 0;
while iIndex < Chunks.Count do
if AnsiCompareText(PChunk(Chunks[iIndex])^.cType, ChunkType) = 0 then
begin
Result := Chunks[iIndex];
break;
end
else
iIndex := iIndex + 1;
end;
end.
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