Re: More than 1 bus in a Node creating distorded audio?
Re: More than 1 bus in a Node creating distorded audio?
- Subject: Re: More than 1 bus in a Node creating distorded audio?
- From: William Stewart <email@hidden>
- Date: Wed, 25 Aug 2010 10:38:38 -0700
it maybe the same, but you haven't checked that the mixer thinks they are the same. So, you need to check the format of each of the buses.
But, maybe there is a more fundamental question to ask - can you use audio queues or even AVAudioPlayers to do what you are doing? Why do you think you need to use the mixer directly? (Just as an FYI, both audio queue and AVAudioPlayer use these same services in their implementation, but you have a higher level API to do this (with no difference to the fidelity of the audio being played))
Bill
On Aug 25, 2010, at 8:36 AM, Patrick Muringer wrote:
> Sound is not distorded but clipped (only for the busses 2
> and on) and exit only on the left (from busses 2 and on)
>
> the strange thing is that bus 0 and 1 play correctly.
>
> The code for each bus is the same.
>
> Patrick
>
> ----- Original Message -----
> Da : Gregory Wieber <email@hidden>
> A : Patrick Muringer <email@hidden>,
> email@hidden
> Oggetto : Re: More than 1 bus in a Node creating distorded
> audio?
> Data : Wed, 25 Aug 2010 08:29:16 -0700
>
>> I agree with Bill -- particular if the distortion sounds
>> like a 'bit reduced' kind of distortion (like the
>> 'bitcrusher' distortion plugin for logic) then it's
>> probably an ASBD format issue. Also, keep in mind that
>> you need to keep your levels from clipping, and since the
>> mixer is additive,
>> multiple busses can result in clipping.
>>
>> On Tue, Aug 24, 2010 at 6:04 PM, William Stewart
>> <email@hidden> wrote:
>>
>>>
>>> On Aug 23, 2010, at 11:55 PM, Patrick Muringer wrote:
>>>
>>>> Thanks Bill for your reply,
>>>>
>>>> You are right, my writing was not clear enough.
>>>>
>>>> I add the callbacks for each bus manually:
>>>> AUGraphSetNodeInputCallback(graph, MixerNode, 0,
>>>> &callback); .
>>>> .
>>>> .
>>>> AUGraphSetNodeInputCallback(graph, MixerNode, N,
>>>> &callback); should I use the loop instead?
>>>
>>> no difference
>>>
>>> But you should make sure that the formats are what you
>>> expect on each and every bus.
>>>
>>> I would guess (from the code below) that you are
>>> expecting all of the buses to be mono, but some are
>> stereo. >
>>>
>>>>
>>>> In the call back, I have a series of IF statements for
>>>> each bus number were I either fill with data or with
>>> 0: >
>>>> if(inBusNumber == 0) {
>>>> if(input.isPlayingTrack1) {
>>>> [input fillBufferWithSampleForBus0:inNumberFrames
>>>> :frameBuffer]; }
>>>> else {
>>>> [input fillBufferWith0:inNumberFrames :frameBuffer];
>>>> }
>>>> }
>>>> .
>>>> .
>>>> if(inBusNumber == N) {
>>>> ...
>>>> }
>>>>
>>>>
>>>> The fillBufferWithSampleForBus (0 to N) does this:
>>>>
>>>> -(void)
>> fillBufferWithSampleForBus0:(UInt32)inNumberFrames
>>>> :(UInt32 *) frameBuffer {
>>>> int packetCount;
>>>> int packetIndex; //Current position in sample
>>>>
>>>> //loop through the buffer and fill the frames
>>>> packetCount = (int)[self.sample1 getPacketCount];
>>>> packetIndex = (int)[self.sample1 getIndex];
>>>>
>>>> self.nbSampleToPlayTrack1 = ((packetCount -
>>>> packetIndex) < inNumberFrames)? (packetCount -
>>>> packetIndex):inNumberFrames; for (int j = 0; j <
>>>> inNumberFrames; j++){ if(self.nbSampleToPlayTrack1 >
>>>> 0) { frameBuffer[j] = [self.sample1 getNextPacket];
>>>> self.nbSampleToPlayTrack1--;
>>>> }
>>>> else {
>>>> self.isPlayingTrack1=FALSE;
>>>> [self.sample1 reset];
>>>> frameBuffer[j] = 0;
>>>> }
>>>> }
>>>> }
>>>>
>>>
>>>> So I guess I'm filling the buffer for each bus.
>>>>
>>>> Everything that I "play" on bus 2 and on (correct
>>>> behavior for busses 0 and 1) is sent clipped only to
>>>> the left of my headset. I taught it was the sample so
>>>> I used the same sample for each bus and I had the same
>> strange behavior. Anything that I do wrong? >
>>> I think its a format issue - make sure you have mono or
>>> stereo as you want as the format for each bus you are
>>> using. If it si mono, you have one buffer to deal with,
>>> if stereo, you have two, and the first buffer is the
>> left channel >
>>> Bill
>>>
>>>>
>>>> Pat
>>>>
>>>>
>>>
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