Re: Displaying WMV from a stream with the WM ASF Reader Filter in a filter graph
From: Bob Dellaca (bobdlxyzzy_at_xtra.co.nz)
Date: 01/22/05
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Date: Sat, 22 Jan 2005 16:14:23 +1300
For the record, here is the source code of a sample unit to play a WMA
(or WMV or ASF) file from a stream (here a TStream (TFileStream)).
It uses DS Pack 2.3.4. As outlined earlier in this thread, it involves
defining your own "custom file type" as a "protocol" and getting the
ASF Reader filter to accept an IStream from your application when the
filter is asked to render a file of that custom protocol
unit Unit2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls,
Forms,
Dialogs, Menus,
ActiveX, DirectShow9;
type
TmyProtStream = class(TInterfacedObject, IStream)
private
aStream: TStream;
aPosition, aLength: Integer;
public
constructor Create(Stream: Tstream);
function Read(pv: Pointer; cb: Longint; pcbRead: PLongint):
HResult;
stdcall;
function Write(pv: Pointer; cb: Longint; pcbWritten: PLongint):
HResult;
stdcall;
function Seek(dlibMove: Largeint; dwOrigin: Longint;
out libNewPosition: Largeint): HResult; stdcall;
function SetSize(libNewSize: Largeint): HResult; stdcall;
function CopyTo(stm: IStream; cb: Largeint; out cbRead: Largeint;
out cbWritten: Largeint): HResult; stdcall;
function Commit(grfCommitFlags: Longint): HResult; stdcall;
function Revert: HResult; stdcall;
function LockRegion(libOffset: Largeint; cb: Largeint;
dwLockType: Longint): HResult; stdcall;
function UnlockRegion(libOffset: Largeint; cb: Largeint;
dwLockType: Longint): HResult; stdcall;
function Stat(out statstg: TStatStg; grfStatFlag: Longint):
HResult;
stdcall;
function Clone(out stm: IStream): HResult; stdcall;
end;
TForm1 = class(TForm)
MainMenu1: TMainMenu;
File1: TMenuItem;
Openwmafile1: TMenuItem;
OpenDialog1: TOpenDialog;
Exit1: TMenuItem;
procedure Openwmafile1Click(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure Exit1Click(Sender: TObject);
private
myProtStream: TmyProtStream;
pFilgraphManager: IMediaControl;
pGraph: IGraphBuilder;
pStream: TFileStream;
procedure CloseIt;
public
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
constructor TmyProtStream.Create(Stream: TStream);
begin
inherited Create;
aStream := Stream;
aLength := aStream.Size;
end;
function TmyProtStream.Read(pv: Pointer; cb: Longint; pcbRead:
PLongint): HResult;
var
ReadLength: Integer;
begin
if (aPosition + cb > aLength) then
ReadLength := aLength - aPosition else
ReadLength := cb;
aStream.Read(pv^, ReadLength);
pcbRead^ := ReadLength;
aPosition := aPosition + ReadLength;
Result := S_OK;
end;
function TmyProtStream.Seek(dlibMove: Largeint; dwOrigin: Longint;
out libNewPosition: Largeint): HResult;
var
newPos: Integer;
begin
case dwOrigin of
STREAM_SEEK_SET: newPos := dlibMove;
STREAM_SEEK_CUR: newPos := aPosition + dlibMove;
STREAM_SEEK_END: newPos := aLength - dlibMove;
else
begin
Result := E_INVALIDARG;
Exit;
end;
end;
if (newPos < 0) or (newPos > aLength) then
Result := E_INVALIDARG else
begin
aPosition := newPos;
aStream.Position := aPosition;
if @libnewPosition <> nil then
libNewPosition := newPos;
Result := S_OK;
end;
end;
function TmyProtStream.Stat(out statstg: TStatStg; grfStatFlag:
Longint): HResult;
begin
if (@statstg = nil) or (grfStatFlag <> STATFLAG_NONAME) then
begin
Result := E_INVALIDARG;
Exit;
end;
FillChar(statstg, sizeof(TStatStg), 0);
statstg.dwType := STGTY_STREAM;
statstg.cbSize := aLength;
Result := S_OK;
end;
function TmyProtStream.Write(pv: Pointer; cb: Longint; pcbWritten:
PLongint): HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.SetSize(libNewSize: Largeint): HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.CopyTo(stm: IStream; cb: Largeint; out cbRead:
Largeint;
out cbWritten: Largeint): HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.Commit(grfCommitFlags: Longint): HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.Revert: HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.LockRegion(libOffset: Largeint; cb: Largeint;
dwLockType: Longint): HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.UnlockRegion(libOffset: Largeint; cb: Largeint;
dwLockType: Longint): HResult;
begin
Result := E_NOTIMPL;
end;
function TmyProtStream.Clone(out stm: IStream): HResult;
begin
Result := E_NOTIMPL;
end;
procedure TForm1.Openwmafile1Click(Sender: TObject);
const
myProt = 'myProt://$%x';
var
aFileName: string;
FileName: WideString;
begin
if OpenDialog1.Execute then
begin
CloseIt;
CoCreateInstance(CLSID_FilterGraph, nil, CLSCTX_INPROC_SERVER,
IID_IFilterGraph2, pGraph);
pFilgraphManager := pGraph as IMediaControl;
pStream := TFileStream.Create(OpenDialog1.FileName, fmOpenRead);
try
myProtStream := TmyProtStream.Create(pStream);
aFileName := Format(myProt, [Integer(myProtStream as IStream)]);
FileName := aFileName;
pGraph.RenderFile(@FileName[1], nil);
except
on E:Exception do
begin
MessageDlg(E.Message, mtError, [mbOk], 0);
pGraph := nil;
CloseIt;
Exit;
end;
end;
pFilgraphManager.Run;
end;
end;
procedure TForm1.CloseIt;
begin
if pGraph <> nil then
begin
pFilgraphManager.Stop;
pGraph := nil;
end;
pFilgraphManager := nil;
myProtStream := nil;
FreeAndNil(pStream);
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
CloseIt;
end;
procedure TForm1.Exit1Click(Sender: TObject);
begin
Close;
end;
end.
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- Previous message: Martin Harvey (Demon account): "Re: newbie question sabout class design"
- In reply to: Bob Dellaca: "Displaying WMV from a stream with the WM ASF Reader Filter in a filter graph"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
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