Profiles and the AsfWriter
Here, we'll briefly look at ways to manipulate the Profile after it has been assigned to the AsfWriter. This is usually accomplished through the AsfWriter's WriterAdvanced2 interface.
Adding Header Info
msdn websiteA short text message can be displayed in Windows Media Player's status panel.
var
hr: HRESULT;
HeaderInfo: IWMHeaderInfo3;
Title: PWideChar;
Idx: word;
Temp: String;
cValue: PWideChar;
begin
hr:= AsfWriter.WriterAdvanced2.QueryInterface(IWMHeaderInfo3, HeaderInfo);
if Failed(hr) then
ShowMessage('Failed to get IWMHeaderInfo3 interface');
Title:= 'Title';
//Test Message
Temp:= 'Short Test Message';
GetMem(cValue, sizeof(WideChar) * Succ(Length(Temp)));
StringToWideChar(Temp, cValue, Length(Temp) + 1);
hr:= HeaderInfo.AddAttribute(0, PWideChar(Title),
Idx, WMT_TYPE_STRING, 0,
PByte(cValue), Length(Temp) * 2);
FreeMem(cValue);
if Failed(hr) then
ShowMessage('Failed to add attribute.');
end;
SetLiveSource
To handle incoming samples correctly, the writer object must be notified whether the source is live.
AsfWriter.WriterAdvanced2.SetLiveSource(True);
Get Connections Count
var
ClientConnections: IWMClientConnections;
hr: HRESULT;
nClients: Cardinal;
ClientProperties: WM_CLIENT_PROPERTIES;
begin
if (not FilterGraph1.Active) then Exit;
hr:= AsfWriter.WriterNetworkSink.QueryInterface(IWMClientConnections, ClientConnections);
if Failed(hr) then
Showmessage('Error - failed to get IWMClientConnections interface');
ClientConnections.GetClientCount(nClients);
Label1.Text:= 'Connections: ' + IntToStr(nClients);
end;