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Thread: How to Send Audio Over RTP UDP VB.Net

  1. #1

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    Question How to Send Audio Over RTP UDP VB.Net

    Hey all,

    Been a while, I've moved along in the projects i have been working on. And currenlty trying to send audio (and eventually video ect) over the network in real time. I've done a fair bit of research and i am fairly sure going down the RTP route is the correct option for me to do this.

    Currently i have succesfully set up a mulitcast UDP sender and reciever, and from there, using a few forums, i was able to get audio coming through on the client. However it is extremely noisy and is playing at the wrong speed. I know i could fix the noise by adding a ulaw encoder/decoder but this add's high compression, and i need original quality (or as close to). And i think this is more a quick fix to the bigger problem.

    So after looking everywhere and not finding anything helpful i've come here. I have some code (below) you can make out a song in it. But it's pretty rough. These are the steps i am trying to get through.

    1. Release the data at a controlled rate
    2. Structure the data into an RTP packet
    3. Read the data and play it as soon as it is recieved (it's important all clients play the song as close to realtime and together as possible, hoping RTP's timing


    I understand the photo from wiki (photo below), and what each chuck is doing, however i don't know how to actually implement something like that, so if anyone has some pointers that would be great.

    Name:  2021-09-10 (3).jpg
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    Audio Code:


    Code:
        Private BlockAlignedStream As WaveStream = Nothing
    
        Private BufferedProvider As BufferedWaveProvider = Nothing
    
        Private WaveReader As WaveStream = Nothing
    
        Private WaveChannel As WaveChannel32 = Nothing
    
        Private WaveOut As IWavePlayer
    
       Friend Function LoadAudioStreamer(ByVal Filepath As String, ByRef IPAddress As Net.IPAddress, ByRef Port As Integer) As Boolean
    
            Try
    
                [Stop]()
    
                Status = Statuses.Loading
    
                 WaveReader = New Mp3FileReader(filePath)
    
                BlockAlignedStream = New BlockAlignReductionStream(WaveReader)
    
                ' Wave channel - reads from file and returns raw wave blocks
                WaveChannel = New WaveChannel32(BlockAlignedStream)
    
                WaveChannel.PadWithZeroes = False
    
                Dim UDPSender As New UDPCoreClass(AddressOf UDPCallback)
    
                If UDPSender.JoinMultiCast("0.0.0.0", IPAddress.ToString, Port) = True Then
    
                    Dim alignment As Integer = WaveChannel.BlockAlign * 32
    
                    Dim buffer As Byte() = New Byte(alignment - 1) {}
    
                    Try
                        Dim numbytes As Integer
    
                        Do
    
                            numbytes = WaveChannel.Read(buffer, 0, alignment)
    
                            UDPSender.SendMulticast(buffer, numbytes)
    
                        Loop While numbytes <> 0
    
                    Catch ex As Exception
    
    
                    End Try
    
                End If
    
            Catch exp As Exception
    
                ' Error in opening file
                WaveOut = Nothing
    
                StatusMessage.Write("Can't open file: " & exp.Message)
    
                Status = Statuses.Error
    
                Return False
    
            End Try
    
        End Function
    
     Friend Function LoadAudioListener(ByRef IPAddress As Net.IPAddress, ByRef Port As Integer) As Boolean
    
            Dim udpListener = New UdpClient(Port)
    
            'udpListener.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, True)
    
            Dim endPoint As IPEndPoint = New IPEndPoint(IPAddress, Port)
    
            Dim waveProvider = New BufferedWaveProvider(New WaveFormat(44000, 16, 2))
    
            waveProvider.DiscardOnBufferOverflow = True
    
            Dim b As Byte()
    
            Dim dso = New DirectSoundOut(100)
    
            dso.Init(waveProvider)
    
            udpListener.JoinMulticastGroup(IPAddress)
    
            dso.Play()
    
            Do
    
                b = udpListener.Receive(endPoint)
    
                waveProvider.AddSamples(b, 0, b.Length)
    
                'waveProvider.read(b, 0, b.Length)
    
    
                Threading.Thread.CurrentThread.Join(0)
    
            Loop While b.Length <> 0
    
            WaveOut.Dispose()
    
            WaveOut.[Stop]()
    
        End Function

    Network Code:

    Code:
    Friend Delegate Sub ServerCallbackDelegate(ByVal bytes() As Byte, ByVal IPAddress As IPAddress, ByVal Port As Integer) ', ByVal sessionID As Int32, ByVal dataChannel As Byte)
    
        Friend ServerCallbackObject As ServerCallbackDelegate
    
        Friend errMsg As String
    
        Private UDPTalker As UdpClient
    
        Private UDPListener As UdpClient
    
        Private GroupEndPoint As IPEndPoint
    
        Private ListeningCue As MessageInQueue
    
        Private isListening As Boolean = False
    
        Private isTalking As Boolean = False
    
        Private isHushing As Boolean = False
    
        Private isDeafening As Boolean = False
    
        Private TargetPort As Integer
    
        Private TargetIP As String
    
        Private BindingIP As String
    
        Private BindingPort As String
    
        Private listenerThread As Thread
    
        Private TalkingState As CurrentState = CurrentState.Stopped
    
        Private ListeningState As CurrentState = CurrentState.Stopped
    
    Friend Function JoinMultiCast(ByVal LocalIPAddress As String, ByVal IPAddress As String, ByVal Port As Integer, Optional ByRef ErrMessage As String = "") As Boolean
    
            Try
    
                If TalkingState = CurrentState.Running Then
    
                    ErrMessage = "The server is already running."
    
                    Return False
    
                End If
    
                BindingIP = LocalIPAddress
    
                TargetIP = IPAddress
    
                TargetPort = Port
    
                Dim GroupIP As IPAddress
    
                GroupIP = Net.IPAddress.Parse(IPAddress)
    
                UDPTalker = New UdpClient(AddressFamily.InterNetwork)
    
                Dim BindingEndPoint As New IPEndPoint(Net.IPAddress.Parse(BindingIP), 0)
    
                UDPTalker.Client.Bind(BindingEndPoint)
    
                GroupEndPoint = New IPEndPoint(GroupIP, TargetPort)
    
                UDPTalker.JoinMulticastGroup(GroupIP, 64)
    
                isTalking = True
    
                Return True
    
            Catch ex As Exception
    
                Return False
    
            End Try
    
        End Function
    
        Friend Sub SendMulticast(ByVal Text As String)
    
            If isTalking AndAlso isHushing = False Then
    
                Try
                    Dim bteSendData() As Byte = Utilities.StrToByteArray(Text)
    
                    'UDPTalker = New UdpClient()
    
                    UDPTalker.Send(bteSendData, bteSendData.Length, GroupEndPoint)
    
                Catch ex As Exception
    
                    Console.WriteLine(ex.Message)
    
                End Try
    
            End If
    
        End Sub
    Last edited by Bensley196; Sep 10th, 2021 at 01:28 AM.

  2. #2
    Angel of Code Niya's Avatar
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    Re: How to Send Audio Over RTP UDP VB.Net

    Seems the problem you're having is that the audio being received is of poor quality, is that right?

    If so, my first question is whether it's the source quality that's poor. Have you verified this?
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  3. #3

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    Re: How to Send Audio Over RTP UDP VB.Net

    Hey Niya, thanks for getting back to me.

    The original song is certainly good, you can play it fine in a player. It also sounds identical if i was to put a WaveOut block on that rather then send it over the network. So i'm either writing it badly to the network, or reading it badly from the network or both.

    The fact that the song is playing so quickly to the person listening, makes me believe that the audio is been played/sent at 200% of the speed, and maybe i'm losing so many packets. Which is what i was thinking using the proper protocal would fix.

    But one step at a time, how would i slow down the speed of which it is sending over the network?

  4. #4
    Angel of Code Niya's Avatar
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    Re: How to Send Audio Over RTP UDP VB.Net

    UDP is an unreliable protocol. My first guess would be that you are losing a lot of UDP datagrams while transmitting the audio. You're going to have to account for that loss in your programs if this is indeed the cause.
    Treeview with NodeAdded/NodesRemoved events | BlinkLabel control | Calculate Permutations | Object Enums | ComboBox with centered items | .Net Internals article(not mine) | Wizard Control | Understanding Multi-Threading | Simple file compression | Demon Arena

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    C++ programmers will dismiss you as a cretinous simpleton for your inability to keep track of pointers chained 6 levels deep and Java programmers will pillory you for buying into the evils of Microsoft. Meanwhile C# programmers will get paid just a little bit more than you for writing exactly the same code and VB6 programmers will continue to whitter on about "footprints". - FunkyDexter

    There's just no reason to use garbage like InputBox. - jmcilhinney

    The threads I start are Niya and Olaf free zones. No arguing about the benefits of VB6 over .NET here please. Happiness must reign. - yereverluvinuncleber

  5. #5

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    Re: How to Send Audio Over RTP UDP VB.Net

    Yes that is very likely, especially if the audio is being sent at a faster rate then needed. The RTP (Real Time Transport Protocal) does this, i just don't understand how to impliment something like it.

    Here is the wiki on it, i believe if i can understand how to implement it, my problems will be reduced greatly

    https://en.wikipedia.org/wiki/Real-t...sport_Protocol

  6. #6
    Angel of Code Niya's Avatar
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    Re: How to Send Audio Over RTP UDP VB.Net

    Quote Originally Posted by Bensley196 View Post
    Yes that is very likely, especially if the audio is being sent at a faster rate then needed. The RTP (Real Time Transport Protocal) does this, i just don't understand how to impliment something like it.

    Here is the wiki on it, i believe if i can understand how to implement it, my problems will be reduced greatly

    https://en.wikipedia.org/wiki/Real-t...sport_Protocol
    That protocol looks very complicated. It might be a good idea to find out of someone has already implemented it in .Net. before you attempt this one on your own. If not then you have to prepare to roll up your sleeves and devote time to studying the protocol so you can implement it yourself.

    However, do note that we are still assuming that the cause of your problem is packet loss. We don't know if that is the cause for sure. If I were you I'd try to find this out before doing anything else.
    Treeview with NodeAdded/NodesRemoved events | BlinkLabel control | Calculate Permutations | Object Enums | ComboBox with centered items | .Net Internals article(not mine) | Wizard Control | Understanding Multi-Threading | Simple file compression | Demon Arena

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    C++ programmers will dismiss you as a cretinous simpleton for your inability to keep track of pointers chained 6 levels deep and Java programmers will pillory you for buying into the evils of Microsoft. Meanwhile C# programmers will get paid just a little bit more than you for writing exactly the same code and VB6 programmers will continue to whitter on about "footprints". - FunkyDexter

    There's just no reason to use garbage like InputBox. - jmcilhinney

    The threads I start are Niya and Olaf free zones. No arguing about the benefits of VB6 over .NET here please. Happiness must reign. - yereverluvinuncleber

  7. #7

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    Re: How to Send Audio Over RTP UDP VB.Net

    I've had a look, i found one application that uses a dll to do it. But i can't confirm where the dll is from, for copyright issues or compatibility checking. There are a few ones for video, but largely seem broken due to how old they are.

    Do you know of any good articles (ones that use good examples or terminoligy won't blow my mind) that go into how to structure a packet? Currently when i'm sending commands over the network (this is TCP) i just covert some text into binary, send it, and then recieve it on the other end. How to create headers and fit correctly into a packet.

    How would i prove that packet loss is the cause, or atlease a big cause of this problem?. Would a counter on every packet send from the server, and compare that to what the client clocks up be a efficient way of doing this?

    It would determin if the packets were arriving badly out of order though.

  8. #8
    Angel of Code Niya's Avatar
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    Re: How to Send Audio Over RTP UDP VB.Net

    Quote Originally Posted by Bensley196 View Post
    How would i prove that packet loss is the cause, or atlease a big cause of this problem?..
    Would I would have done is write a very simple program that breaks up the file into pieces and feed those pieces as a stream into another part of the program that tries to play it. The idea is to simulate what happens when the file is streamed from one endpoint to the next without all the complexity of actual UDP communication. You could then modify the program to artificially "drop packets" to see what would happen.

    Quote Originally Posted by Bensley196 View Post
    Do you know of any good articles (ones that use good examples or terminoligy won't blow my mind) that go into how to structure a packet? Currently when i'm sending commands over the network (this is TCP) i just covert some text into binary, send it, and then recieve it on the other end. How to create headers and fit correctly into a packet.
    Are you talking about the Real Time Transport Protocol?
    Treeview with NodeAdded/NodesRemoved events | BlinkLabel control | Calculate Permutations | Object Enums | ComboBox with centered items | .Net Internals article(not mine) | Wizard Control | Understanding Multi-Threading | Simple file compression | Demon Arena

    Copy/move files using Windows Shell

    C++ programmers will dismiss you as a cretinous simpleton for your inability to keep track of pointers chained 6 levels deep and Java programmers will pillory you for buying into the evils of Microsoft. Meanwhile C# programmers will get paid just a little bit more than you for writing exactly the same code and VB6 programmers will continue to whitter on about "footprints". - FunkyDexter

    There's just no reason to use garbage like InputBox. - jmcilhinney

    The threads I start are Niya and Olaf free zones. No arguing about the benefits of VB6 over .NET here please. Happiness must reign. - yereverluvinuncleber

  9. #9

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    Re: How to Send Audio Over RTP UDP VB.Net

    Ah ok so skip the network all together. And if the out come is similar then that's it.


    Just dealing with packets in UDP in general that relate to .net, but i relise now that is something i can find pretty easy hahah. I'll see how i go with your suggestion

  10. #10
    Angel of Code Niya's Avatar
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    Re: How to Send Audio Over RTP UDP VB.Net

    Quote Originally Posted by Bensley196 View Post
    Ah ok so skip the network all together. And if the out come is similar then that's it.
    Exactly.

    Quote Originally Posted by Bensley196 View Post
    Just dealing with packets in UDP in general that relate to .net, but i relise now that is something i can find pretty easy hahah. I'll see how i go with your suggestion
    Yes that information is very easy to find. Winsock in .Net is well documented and the UDP protocol is also well documented.
    Treeview with NodeAdded/NodesRemoved events | BlinkLabel control | Calculate Permutations | Object Enums | ComboBox with centered items | .Net Internals article(not mine) | Wizard Control | Understanding Multi-Threading | Simple file compression | Demon Arena

    Copy/move files using Windows Shell

    C++ programmers will dismiss you as a cretinous simpleton for your inability to keep track of pointers chained 6 levels deep and Java programmers will pillory you for buying into the evils of Microsoft. Meanwhile C# programmers will get paid just a little bit more than you for writing exactly the same code and VB6 programmers will continue to whitter on about "footprints". - FunkyDexter

    There's just no reason to use garbage like InputBox. - jmcilhinney

    The threads I start are Niya and Olaf free zones. No arguing about the benefits of VB6 over .NET here please. Happiness must reign. - yereverluvinuncleber

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