Hank,
I have included the key methods which decodes and renders the audio
data.
i uses the following structures to hold the data
typedef struct
{
UInt32 mDataByteSize;
UInt32 mNumOfPackets;
UInt32 mPacketOffset;
UInt32 mNumOfChannels;
UInt32 mBytesPerPacket;
char *mData;
AudioStreamPacketDescription *mPacketDesc;
}AudioConverterBuffer;
typedef struct
{
UInt32 mDataByteSize;
UInt32 mNumOfPackets;
UInt32 mBufferIndex;
UInt32 mNumOfChannels;
UInt32 mPacketOffset;
UInt32 mBytesPerPacket;
char *mData;
AudioStreamPacketDescription *mPacketDesc;
}AudioPlayBuffer;
-----------------------
- (void)handleAudioPackets:(const void *)inInputData
numberOfBytes:(UInt32)inNumberBytes
numberOfPackets:(UInt32)inNumberPackets
streamPacketDescriptions:(AudioStreamPacketDescription *)inPacketDescription
{
OSStatus error = noErr;
AudioBufferList fillBufferList;
AudioStreamPacketDescription *outputPacketDesc = NULL;
UInt32 inOutDataPackets;
UInt32 numOutputPackets;
UInt64 dataSize;
size_t bufSpaceRemaining;
if (_converter == NULL) {
error = AudioConverterNew(&mRawFormat, &mSourceFormat, &_converter);
if (error) {
[self printErrorMessage:@"AudioConverterNew failure"
withStatus:error];
return;
}
[self getAndSetMagicCookie];
_converterOutputBuffer = (char *)malloc(sizeof(char) * kDefaultBufSize);
}
numOutputPackets = kDefaultBufSize / mSourceFormat.mBytesPerPacket;
_converterBuffer.mDataByteSize = inNumberBytes;
_converterBuffer.mNumOfPackets = inNumberPackets;
_converterBuffer.mNumOfChannels = mSourceFormat.mChannelsPerFrame;
_converterBuffer.mPacketOffset = 0;
_converterBuffer.mBytesPerPacket = inNumberBytes / inNumberPackets;
_converterBuffer.mData = (char *)inInputData;
_converterBuffer.mPacketDesc = inPacketDescription;
while (_converterBuffer.mPacketOffset < inNumberPackets) {
fillBufferList.mNumberBuffers = 1;
fillBufferList.mBuffers[0].mNumberChannels =
mSourceFormat.mChannelsPerFrame;
fillBufferList.mBuffers[0].mDataByteSize = kDefaultBufSize;
fillBufferList.mBuffers[0].mData = _converterOutputBuffer;
inOutDataPackets = numOutputPackets;
error = AudioConverterFillComplexBuffer(_converter,
encoderDataProc,
self,
&inOutDataPackets,
&fillBufferList,
outputPacketDesc);
dataSize = fillBufferList.mBuffers[0].mDataByteSize;
bufSpaceRemaining = kDefaultBufSize - _bytesFilled;
if (bufSpaceRemaining < dataSize) {
[self enqueueAudioPlayBuffer];
}
_playBuffer[_fillBufferIndex].mDataByteSize = dataSize;
memcpy(_playBuffer[_fillBufferIndex].mData,
fillBufferList.mBuffers[0].mData,dataSize);
_playBuffer[_fillBufferIndex].mPacketDesc = NULL;
_bytesFilled += dataSize;
_packetsFilled += inOutDataPackets;
}
}
//Audio Unit Render Callback method
- (OSStatus)handleRenderInputWithFlags:(AudioUnitRenderActionFlags
*)ioActionFlags
timeStamp:(const AudioTimeStamp *)inTimeStamp
busNumber:(UInt32)inBusNumber
numberOfFrames:(UInt32)inNumberFrames
bufferList:(AudioBufferList *)ioData
{
char *sourceBuffer = _playBuffer[_playBufferIndex].mData;
UInt32 byteOffset = _playBuffer[_playBufferIndex].mPacketOffset *
_playBuffer[_playBufferIndex].mBytesPerPacket;
memcpy(ioData->mBuffers[0].mData, &sourceBuffer[byteOffset],
ioData->mBuffers[0].mDataByteSize);
_playBuffer[_playBufferIndex].mPacketOffset += inNumberFrames;
return noErr;
}
//AudioUnit Render Notification Method
- (OSStatus)handleRenderNotification:(AudioUnitRenderActionFlags *)ioActionFlags
timeStamp:(const AudioTimeStamp *)inTimeStamp
busNumber:(UInt32)inBusNumber
numberOfFrames:(UInt32)inNumberFrames
bufferList:(AudioBufferList *)ioData
{
if (*ioActionFlags & kAudioUnitRenderAction_PostRender) {
UInt32 maxPackets = _playBuffer[_playBufferIndex].mDataByteSize / 4;
if (_playBuffer[_playBufferIndex].mPacketOffset >= maxPackets) {
pthread_mutex_lock(&_queueBufferMutex);
_bufferUsed[_playBufferIndex] = NO;
pthread_cond_signal(&_queueBufferReadyCond);
pthread_mutex_unlock(&_queueBufferMutex);
if (++_playBufferIndex >= kMaxPlayBuffer) {
_playBufferIndex = 0;
}
}
}
return noErr;
}
- (OSStatus)handleEncoderDataProc:(AudioConverterRef)inAudioConverter
numberOfPackets:(UInt32 *)ioNumberDataPackets
bufferList:(AudioBufferList *)ioData
packetDescription:(AudioStreamPacketDescription
**)outputPacketDescription
{
if (*ioNumberDataPackets > _converterBuffer.mDataByteSize) {
*ioNumberDataPackets = _converterBuffer.mDataByteSize;
}
UInt32 offset = _converterBuffer.mPacketOffset;
AudioStreamPacketDescription *pDesc = _converterBuffer.mPacketDesc;
ioData->mNumberBuffers = 1;
ioData->mBuffers[0].mDataByteSize = pDesc[offset].mDataByteSize;
ioData->mBuffers[0].mNumberChannels = _converterBuffer.mNumOfChannels;
ioData->mBuffers[0].mData =
&_converterBuffer.mData[pDesc[offset].mStartOffset];
if (outputPacketDescription) {
if (_converterBuffer.mPacketDesc) {
*outputPacketDescription = &pDesc[_converterBuffer.mPacketOffset];
(*outputPacketDescription)->mStartOffset = 0;
} else {
*outputPacketDescription = NULL;
}
}
_converterBuffer.mPacketOffset += *ioNumberDataPackets;
return noErr;
}
Thanks
Sasikumar
On 27-Apr-2011, at 7:08 AM, Hank Heijink (Mailinglists) wrote:
> I believe Audio units need 44100 Hz, but I'm not sure about that. Regardless,
> decoding mp3 with an AudioConverter should not introduce any glitches at that
> rate - any iOS device should be able to handle that without issues.
>
> The 4096 is the right value for any iOS device. Without seeing your code, I
> don't know where your glitches are coming from. Are you by any chance reading
> from disk on the same thread that you're playing audio on, or doing anything
> else that could cause that thread to block?
>
> Hank
>
> On Apr 26, 2011, at 9:19 PM, Sasikumar JP wrote:
>
>> Hank,
>> I have tried with by setting "kAudioUnitProperty_MaximumFramesPerSlice"
>> property as 4096 for Mixer and EQ Audio Units. Now audio playback did not
>> stop when the device goes to sleep mode.
>>
>> But i hear glitches along with Audio.
>>
>> I have looked at apple sample code MixerHost. it plays nicely even the
>> device is in sleep mode. But Apple sample code simply mixes 2 PCM audio
>> files and play it.
>>
>> Where as my application converts the stream mp3 in to PCM using
>> AudioConverterFillComplexBuffer API in realtime and plays it using
>> AudioUnit.
>>
>> Does the Audio Conversion introduce any delay in audio packet generation,
>> which could leads to the glitches in audio playback (when the device in the
>> sleep mode)?
>>
>> Should i set different sample value(4096) for different hardware (iPod Touch
>> 2nd/3rd/4th Gen...etc)
>>
>> How to derive the number of samples for different Sampling Rate? (As per the
>> Apple document 4096 samples @ 44.1kHz)
>>
>> Thanks
>> Sasikumar JP
>>
>> On 26-Apr-2011, at 8:44 PM, Hank Heijink (Mailinglists) wrote:
>>
>>> You're thinking of kAudioUnitProperty_MaximumFramesPerSlice
>>> (http://developer.apple.com/library/ios/#qa/qa1606/_index.html). You have
>>> to set that to 4096 frames per slice for every audio unit that's not the
>>> remoteIO unit.
>>>
>>> Hank
>>>
>>> On Apr 26, 2011, at 11:05 AM, Gregory Wieber wrote:
>>>
>>>> In the iOS docs on audio sessions there's a section on apps becoming
>>>> background tasks. I don't have them in front of me now, but you have to
>>>> set a property for buffer size when the app goes into the background for
>>>> it to work.
>>>>
>>>> Sent from my iPhone
>>>>
>>>> On Apr 25, 2011, at 9:38 PM, Sasikumar JP <[email protected]> wrote:
>>>>
>>>>> Hi,
>>>>> I am working on streaming audio player application for iOS. currently i
>>>>> am experimenting with AudioQueue and AudioUnit for playback.
>>>>>
>>>>> Both works fine in the normal condition. But AudioUnit playback stopped
>>>>> playing when device (ipod touch 2nd gen) goes to sleep mode, where as it
>>>>> works fine with AudioQueue.
>>>>>
>>>>> I have set "kAudioSessionCategory_MediaPlayback" session category for
>>>>> both cases. I assume this session category should continue the playback
>>>>> even in sleep mode.
>>>>>
>>>>> I am not sure what i am missing here.
>>>>>
>>>>> I want to add pan/effects features to my application, so i am trying with
>>>>> AudioUnit.
>>>>>
>>>>> Any help is highly appreciated
>>>>>
>>>>> Thanks
>>>>> Sasikumar JP _______________________________________________
>>>>> Do not post admin requests to the list. They will be ignored.
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>>>>>
>>>>> This email sent to [email protected]
>>>> _______________________________________________
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>>>> This email sent to [email protected]
>>>>
>>>
>>
>>
>
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