Low latency audio streaming

The latencies are due to device drivers (which are naturally dependent on the device manufacturer) and not on any particular Symbian code. Not knowing which device you are using, I would suggest you play around a bit with different buffer size values and then accept the best you get - playback latencies of 50-500 ms are quite OK depending on the device. Remember, this is the total user-mode-app to physical sound generation latency and is not that bad at all if you consider how many software layers and buffers there are in between.

Sure, N-Gage has no problem with this. My post was meant to indicate that your problems are nothing platform (Symbian OS) specific but rather, device specific. I have seen two 7650 phones with same software versions exhibit different audio and/or video characteristics only because the hardware or the  place of fabrication was different. Yes - the hardware does differ within the same model family ( nasty, isn't it ? ).

Still, even if you do have an N-Gage, the prototypes surely are different from the shelf models.

Hi zeep,

I am trying to implement multi-channle sound via CMdaAudioOutputStream.
I found an AudioEngine `sidplay', it does support EPOC/S60,
but it can only play the defined format .sid, and that engile seems pretty complex for S60 only
Are you interested in studying SIDPLAY and writing our S60 AudioEngine?

Cheer,
ouseka

Hi zeep,

Are you reading the source code of MikMod? me 2...

Regards,
ouseka

Oh, you are the senior in these fileds, and very glad to meet you all at this pretty Symbian Dev Site

Cheer,
ouseka

Hi all,

All of you have good knowledge in Audio.  I am facing a problem in AudioConvertUtility of Symbian OS.  After successfully calling OpenL() method (I checked ErrorCode) the output buffer size is zero.  Why?

I am pasting the code for you.

// TInputStream.cpp
//
// Copyright (c) 2003 Symbian Ltd.  All rights reserved.
//

#include <f32file.h>
#include <barsread.h>
#include <eikbtpan.h>
#include <eikcmbut.h>
#include <eiklabel.h>
#include <eikmover.h>
#include <eikbtgpc.h>
#include <eikon.hrh>
#include <eikon.rsg>
#include "TInputStream.h"
#include <MdaAudioSampleEditor.h>


const TInt KBufferSize = 16000;

_LIT(KRecorderFile, "C:\\System\\Apps\\record.wav");

RFs fs;
RFile file;

//
// CTInputStreamAppView
//

CTInputStreamAppView::CTInputStreamAppView():
   CCoeControl()
   {}

CTInputStreamAppView::~CTInputStreamAppView()
   {
   delete iBitmapGc;
   delete iBitmapDev;
   delete iBitmap;
   }

void CTInputStreamAppView::ConstructL(const TRect& aRect)
   {
   CreateWindowL();
    SetRect(aRect);
   ActivateL();

   const CFont* font = ControlEnv()->NormalFont();
   iFontHeight = font->HeightInPixels();
   iFontAscent = font->AscentInPixels();

   iBitmap = new(ELeave) CFbsBitmap;
   User::LeaveIfError(iBitmap->Create(aRect.Size(),Window().DisplayMode()));
   iBitmapDev = CFbsBitmapDevice::NewL(iBitmap);
   iBitmapDev->CreateContext(iBitmapGc);

   iBitmapGc->UseFont(font);
   iBitmapGc->SetBrushStyle(CGraphicsContext::ESolidBrush);
   iBitmapGc->SetBrushColor(KRgbWhite);

   iBitmapGc->Clear();
   }

void CTInputStreamAppView::AddMessage(const TDesC& aMessage)
   {
   iBitmapGc->CopyRect(TPoint(0,-iFontHeight),Rect());
   const TRect messageRect(0,Rect().iBr.iY - iFontHeight,Rect().iBr.iX,Rect().iBr.iY);
   iBitmapGc->DrawText(aMessage,messageRect,iFontAscent);
   Window().Invalidate();
   }

void CTInputStreamAppView::Draw(const TRect& aRect) const
   {
   CWindowGc& gc = SystemGc();
   gc.BitBlt(aRect.iTl,iBitmap,aRect);
   }

//
//  CTInputStreamAppUi
//

CTInputStreamAppUi::~CTInputStreamAppUi()
    {
   delete iInput;
   delete iOutput;
   iBuffer.ResetAndDestroy();
   if (iAppView)
      {
      RemoveFromStack(iAppView);
      delete iAppView;
      }
   if(iConverter)
      delete iConverter;

    }

void CTInputStreamAppUi::ConstructL()
    {
    BaseConstructL();
   iAppView = new(ELeave) CTInputStreamAppView;
   iAppView->ConstructL(ClientRect());
   AddToStackL(iAppView);

   iSettings.iChannels = TMdaAudioDataSettings::EChannelsMono;
   iSettings.iSampleRate= TMdaAudioDataSettings::ESampleRate8000Hz;

   iInput = CMdaAudioInputStream::NewL(*this);
   iInput->Open(&iSettings);

   iOutput = CMdaAudioOutputStream::NewL(*this);
   iOutput->Open(&iSettings);

   iConverter = new (ELeave) log_test;
   iConverter->ConstructL();

   TDes8* buffer = new(ELeave) TBuf8<KBufferSize>;
   buffer->SetMax();
   CleanupStack::PushL(buffer);
   User::LeaveIfError(iBuffer.Append(buffer));
   CleanupStack::Pop(buffer);
   buffer = new(ELeave) TBuf8<KBufferSize>;
   buffer->SetMax();
   CleanupStack::PushL(buffer);
   User::LeaveIfError(iBuffer.Append(buffer));
   CleanupStack::Pop(buffer);
   buffer = new(ELeave) TBuf8<KBufferSize>;
   buffer->SetMax();
   CleanupStack::PushL(buffer);
   User::LeaveIfError(iBuffer.Append(buffer));
   CleanupStack::Pop(buffer);
   
    }

void CTInputStreamAppUi::HandleCommandL(TInt aCommand)
   {
   switch (aCommand)
      {
   case ETInputStreamCmdRecord:
      RecordL();
      break;
   case ETInputStreamCmdPlay:
      PlayL();
      break;
   case EAknSoftkeyBack:
      CEikAppUi::Exit();
      break;
      }
   }

void CTInputStreamAppUi::MaiscOpenComplete(TInt aError)
   {
   
   
   if (aError != KErrNone)
      {
      TBuf<32> buf(_L("Input err "));
      buf.AppendNum(aError);
      iAppView->AddMessage(buf);
      }
   OpenCompleteL(aError);
   
   User::InfoPrint( _L( "Open Complete" ) );


   }

void CTInputStreamAppUi::MaiscBufferCopied(TInt aError, const TDesC8& aBuffer)
   {
   
   TDes8* buffer = new(ELeave) TBuf8<KBufferSize>;
   buffer->Trim();

   //buffer->Append('v');
   TBuf<32> buf(_L("Buf "));

   if (&aBuffer == iBuffer[0])
      buf.AppendNum(1);
   else if (&aBuffer == iBuffer[1])
      buf.AppendNum(2);
   else if (&aBuffer == iBuffer[2])
      {
      buf.AppendNum(3);
      iState = EOpen;
      }

   buf.Append(_L(" full, err "));
   buf.AppendNum(aError);
   iAppView->AddMessage(buf);
   iConverter->BufferWriteL(aBuffer,*buffer);
   User::LeaveIfError(aError);
   }

void CTInputStreamAppUi::MaiscRecordComplete(TInt aError)
   {
   iState = EOpen;
   TBuf<32> buf(_L("Record complete, err "));
   
   file.Flush();
   file.Close();
   fs.Close();
   iAppView->AddMessage(_L("File Closed"));
   buf.AppendNum(aError);
   iAppView->AddMessage(buf);
   User::LeaveIfError(aError);
   }

void CTInputStreamAppUi::MaoscOpenComplete(TInt aError)
   {
   if (aError != KErrNone)
      {
      TBuf<32> buf(_L("Output err "));
      buf.AppendNum(aError);
      iAppView->AddMessage(buf);
      }
   OpenCompleteL(aError);
   }

void CTInputStreamAppUi::MaoscBufferCopied(TInt aError, const TDesC8& aBuffer)
   {
   TBuf<32> buf(_L("Buf "));
   
   if (&aBuffer == iBuffer[0])
      buf.AppendNum(1);
   else if (&aBuffer == iBuffer[1])
      buf.AppendNum(2);
   else if (&aBuffer == iBuffer[2])
      buf.AppendNum(3);
   buf.Append(_L(" played, err "));
   buf.AppendNum(aError);

   iAppView->AddMessage(buf);

   User::LeaveIfError(aError);
   }

void CTInputStreamAppUi::MaoscPlayComplete(TInt aError)
   {
   iState = EOpen;
   if (aError == KErrUnderflow)
      aError = KErrNone;
   TBuf<32> buf(_L("Play complete, err "));
   buf.AppendNum(aError);
   iAppView->AddMessage(buf);
   User::LeaveIfError(aError);
   }

void CTInputStreamAppUi::OpenCompleteL(TInt aError)
   {
   User::LeaveIfError(aError);

   if (iState == EClosed)
      {
      iState = EFirstOpenSuccessful;
      }
   else
      {
      iState = EOpen;
      iAppView->AddMessage(_L("Ready"));
      iInput->SetGain(iInput->MaxGain());
      iOutput->SetVolume(iOutput->MaxVolume() / 2);
      }

   }

void CTInputStreamAppUi::RecordL()
   {
   

   User::LeaveIfError(fs.Connect());

    //CleanupClosePushL(file);
   file.Replace(fs,KRecorderFile, EFileShareAny | EFileStream | EFileWrite);

   if (iState != EOpen)
      User::Leave(KErrNotReady);

   iState = ERecording;
   iAppView->AddMessage(_L("File Opened"));
   for (TInt index = 0; index < iBuffer.Count(); index++)
      {
      iInput->ReadL(*iBuffer[index]);
      }
   
   }

void CTInputStreamAppUi::PlayL()
   {
   if (iState != EOpen)
      User::Leave(KErrNotReady);

   iState = EPlaying;

   for (TInt index = 0; index < iBuffer.Count(); index++)
      {
      iOutput->WriteL(*iBuffer[index]);
      }
   }

//
// CTInputStreamApp
//

TUid CTInputStreamApp::AppDllUid() const
   {
   return KUidMdaAudioInputStreamingTestApp;
   }

CApaDocument* CTInputStreamApp::CreateDocumentL()
   {
   return new(ELeave) CTInputStreamDocument(*this);
   }


//
// CTInputStreamDocument
//

CTInputStreamDocument::CTInputStreamDocument(CEikApplication& aApp)
   : CAknDocument(aApp)
   {}

CEikAppUi* CTInputStreamDocument::CreateAppUiL()
   {
    return new (ELeave) CTInputStreamAppUi;
   }

EXPORT_C CApaApplication* NewApplication()
   {
   return new CTInputStreamApp;
   }

GLDEF_C TInt E32Dll(TDllReason)
   {
   return KErrNone;
   }


log_test::log_test()
{
   
}

void log_test::ConstructL()
{
   iAudioConvertUtility = CMdaAudioConvertUtility::NewL(*this);
   
   iDestType = new (ELeave) CMdaAudioType;
   iSrcType = new (ELeave) CMdaAudioType;

   iSrcType->iFormat = new TMdaRawAudioClipFormat;
   iDestType->iFormat = new TMdaWavClipFormat;

   iSettings.iChannels = 1;  //TMdaAudioDataSettings::EChannelsMono;
   iSettings.iSampleRate =8000; //TMdaAudioDataSettings::ESampleRate8000Hz;

   iSettings1.iChannels = 1;  //TMdaAudioDataSettings::EChannelsMono;
   iSettings1.iSampleRate =8000; //TMdaAudioDataSettings::ESampleRate8000Hz;

   iCodecSrc = new TMdaU8PcmRawAudioCodec;  //(TMdaPcmWavCodec::E16BitPcm);

   iCodec = new (ELeave) TMdaPcmWavCodec(TMdaPcmWavCodec::E8BitPcm); /*TMdaMulawWavCodec */
   isrcdesc = NULL;
   idesdesc = NULL;
   
};

void log_test::MoscoStateChangeEvent(CBase* aObject, TInt aPreviousState, TInt aCurrentState, TInt aErrorCode)
{
      TTimeIntervalMicroSeconds  temp(0);
      
      if (aErrorCode == KErrNone)
      {
      TBuf<32> buf(_L("Input err "));
      buf.AppendNum(aErrorCode);
      file.Write(*(*idesdesc).iDes);
      }
   return;
}

log_test::~log_test()
{
   if(iAudioConvertUtility)
      delete iAudioConvertUtility;
   if(isrcfrmt)
      delete isrcfrmt;
   if(itarfrmt)
      delete itarfrmt;
}

void log_test::BufferWriteL(const TDesC8& aTemp1, TDes8& aTemp2)
{
   
   aTemp2.TrimAll();
   aTemp2.Zero();
   //Temp1.TrimAll();
   _LIT(FilenameSrc, "temp.wav");
   //aTemp2.Append(aTemp1);
   /*_LIT(FilenameDest, "\\system\\note1.wav"); */

   if(isrcdesc)
      delete isrcdesc;
   if(idesdesc)
      delete idesdesc;
   
   isrcdesc = new(ELeave) TMdaDesClipLocation(aTemp1);
   idesdesc = new(ELeave) TMdaDesClipLocation(aTemp2);

   fileSrc=new TMdaFileClipLocation (FilenameSrc);
//   fileDest= new TMdaFileClipLocation(FilenameDest); */


   iAudioConvertUtility->OpenL(isrcdesc,idesdesc,iSrcType->iFormat,iDestType->iFormat,iCodecSrc,&iSettings1,iCodec,&iSettings);  
   //User::WaitForAnyRequest();
   //iAudioConvertUtility->OpenL(FilenameSrc,FilenameDest); //,iDestType->iFormat,iCodec,&iSettings);  
   
//   delete isrcdesc;
//   delete idesdesc;

}