I am working with a network application, so someting i will lose packet or where i have start play , there is no data for playing. this is my source code:
struct AQPlayerState *pAqData = (struct AQPlayerState *) m_aqData ;
UInt32 numBytesReadFromFile = 0 ;
UInt32 numPackets = 0 ;
char * pdata = (char *)inBuffer->mAudioData ;
for ( int i = 0 ; i < pAqData->mNumPacketsToRead ; ++i )
{
unsigned int uiRead =GetOneFrame(pdata, pAqData->bufferByteSize - numBytesReadFromFile) ;
if ( uiRead == 0 )
break ;
AudioStreamPacketDescription * packetDescs = pAqData->mPacketDescs + i ;
packetDescs->mDataByteSize = uiRead ;
packetDescs->mStartOffset = numBytesReadFromFile ;
packetDescs->mVariableFramesInPacket = 0 ;
numBytesReadFromFile += uiRead ;
pdata += uiRead ;
++numPackets ;
}
if (numPackets > 0)
{
inBuffer->mAudioDataByteSize = numBytesReadFromFile ;
OSStatus state = AudioQueueEnqueueBuffer (pAqData->mQueue, inBuffer, (pAqData->mPacketDescs ? numPackets : 0), pAqData->mPacketDescs) ;
NSLog(@"HandleOutputBuffer packet count:%lu, res:%lu", numPackets, state) ;
}
else
{
inBuffer->mAudioDataByteSize = 0 ;
(*(pAqData->mPacketDescs)).mDataByteSize = 0 ;
(*(pAqData->mPacketDescs)).mStartOffset = 0 ;
(*(pAqData->mPacketDescs)).mVariableFramesInPacket = 0 ;
OSStatus state = AudioQueueEnqueueBuffer (pAqData->mQueue, inBuffer, 0, nil) ;
NSLog(@"no packet: enqueuebuffer res:%ld", state) ;
}
but if these is no packet, i get a error kAudioQueueErr_BufferEmpty,so i just want to know how to play a silence frame with aac_he type(vbr)
The question is asked by me 2 years ago, I have get a solution actually.
The solution is that recording a silence packet using recording tools.
First find a recording tool and set the record parameters to AAC_HE. Then start recording and keep quiet. Save the file.
When your app launches, load the file in memory and use it when no data to playback.
As audio queue is a pull-mode api, it is not appropriate if we get data through network. Open AL is a push-mode api but it only supports uncompressed format, so maybe we should decode the compressed data using core-audio then playback using Open AL.