Re: NewTimePitch AudioUnit increases volume?
Re: NewTimePitch AudioUnit increases volume?
- Subject: Re: NewTimePitch AudioUnit increases volume?
- From: Bruno Di Giorgi <email@hidden>
- Date: Thu, 06 Sep 2012 09:30:10 +0200
Thank you Brian for your right answer.
I have the classic graph AudioFilePlayer, NewTimePitch and DefaultOutput.
Inputs and outputs of these Units have identical streamFormat (and then number of channels).
So, it's not related to stream format but as I said you're right! It is definetly related to stereo image.
I made two tests:
1. I made mid/side codify in between NewTimePitch and DefaultOutput to hear the difference
2. I compared NewTimePitch and TimePitch
The main result is that TimePitch has a lot better quality, and it is mainly due to phase coherency in both channels.
In fact: when I switch from mid to side with NewTimePitch, I can't hear any difference (when the unit is working, i.e. not at (rate==1,pitch==0)).
When I switch from mid to side with old TimePitch phase is consistent so I hear at (rate!=1,pitch!=0) exactly what I hear at (rate==1,pitch==0).
Not hearing difference from mid to side with NewTimePitch means that when listening in stereo channels are summing and I hear that volume increase.
This lead me to think that the NewTimePitch computing algorithm is messing with phase somehow.
Il giorno 06/set/2012, alle ore 04:38, Brian Willoughby ha scritto:
>
> On Sep 5, 2012, at 10:04, Bruno Di Giorgi wrote:
>> I'm experimenting with NewTimePitch Unit, and having success in doing time and pitch changing in real time.
>> However I have a little issue:
>>
>> When time (kTimePitchParam_Rate) changes from 1 or pitch (kNewTimePitchParam_Pitch) changes from 0 Volume rises of a factor of about 1.3.
>> Then comes back to normal when values are back to defaults, as if unit with default values is bypassed then actives (rising volume) when changing values.
>> Now I'm compensating in OutputUnit, lowering volume to about 0.7.
>> Is this the normal behavior of this unit?
>
> No. I don't think so, but I've only used the older TimePitch units.
>
> I guess you have a mono/stereo issue in your graph, such that left+right are being combined in the TimePitch unit. That would explain the 3 dB change in volume. As to how you fix this, I don't know, but you should check your graph to make sure all inputs and outputs match in channel count.
>
> Brian Willoughby
> Sound Consulting
>
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