Indy 10 Broadcast and AData - delphi

Question

I'm trying to make a text chat through indy udp component and here is the codes for server and client
udp Client:
procedure TForm1.SendClick(Sender: TObject);
begin
sendtocl.Broadcast(usertype.Text, 12000);
usertype.Clear;
end;
onread Server :
procedure TForm1.UDPReceiverUDPRead(AThread: TIdUDPListenerThread; const AData: TIdBytes; ABinding: TIdSocketHandle);
var
AudioDataSize: Integer;
AudioData : Pointer;
begin
try
EnterCriticalSection(Section);
try
AudioDataSize := Length(AData);
if AudioDataSize > 10 then
begin
try
if not Player.Active then
begin
Player.Active := True;
Player.WaitForStart;
end;
except
end;
if BlockAlign > 1 then Dec(AudioDataSize, AudioDataSize mod BlockAlign);
AudioData := AudioBuffer.BeginUpdate(AudioDataSize);
try
BytesToRaw(AData, AudioData^, AudioDataSize);
finally
AudioBuffer.EndUpdate;
end;
end else
begin
Player.Active := False;
Player.WaitForStop;
end;
finally
LeaveCriticalSection(Section);
end;
except
end;
begin
chatboxmsg.Lines.Add(BytesToString(AData));
end;
end;
its working good but i had problem if i use the udp client with other purpose like send buffer "To send audio " the chatboxmsg.line shows flooded data of audio buffer any way to make the server read separated Adata ?

Answer 1

In UDP, every send (Broadcast(), Send(), SendBuffer(), etc) transmits a distinct datagram. The OnUDPRead event is triggered for every datagram that is received. AData contains the data of one distinct datagram at a time.
So, you have two choices:
format your datagrams in such a way (such as putting a header at the front of the data) so that they identify the type of data they carry. That way, your OnUDPRead handler can read the identifier/header and know whether to put the remaining data to ChatBoxMsg or pass it to the sound system.
if you do not want to (or cannot) change your datagram formats, then you will have to send text and audio datagrams to different ports. You can use a single TIdUDPServer object listening on multiple ports at the same time (that is what its Bindings collection is for), in which case the ABinding parameter of the OnUDPServer event will tell you which port AData was received on. Or, just use two separate TIdUDPServer objects, each one listening on a different port, and assign different OnUDPRead handlers to each one.