Re: long FIR filters
Re: long FIR filters
- Subject: Re: long FIR filters
- From: alex <email@hidden>
- Date: Fri, 2 Feb 2007 10:26:26 -0800
Take a look at vDSP. You can use it to do FFT style convolution and it also has a direct form implementation of a convolve as well (which I haven't used).
http://developer.apple.com/documentation/Performance/Conceptual/vDSP/intro_chap/chapter_1_section_1.html
a
At 7:12 PM +0100 2/2/07, Cor Jansen wrote:
>Thanks for the very interesting information.
>
>I would like very little latency.
>I was wondering if with the current processor speeds and architecture (SIMD instructions?), it would be possible
>to get good results with a direct form FIR implementation.
>
>E.g: for a 44.1Kc samplerate stereo signal, and with 10.000 taps, I would need about 880 miljoen multiply-accumulations.
>With a 1 GHz processor I will need about one multiply-add per clock.
>I suppose the Intel processor of the apple computers has some kind of Altivec (MMX?) architecture to do several
>multiple-adds each clock? Am I correcect?
>
>Does anybody know how to work this out? Preferrable without writing assembly instructions.
>
>Cor
>
>
>----- Original Message ----- From: <email@hidden>
>To: "coreaudio" <email@hidden>
>Sent: Friday, February 02, 2007 6:48 PM
>Subject: Re: long FIR filters
>
>>>Unfortunately this technique has been patented (#6625629)
>>>
>>>http://www.google.com/patents?vid=USPAT6625629&id=GgAPAAAAEBAJ&dq=Efficient+Convolution+without+Input-Output+Delay
>>>
>>
>>Only for low-latency partitioned convolution with unequal partition sizes
>>(and even that is a bit moot). The plain partitioned convolution (which
>>can still give usefully low latency) is ad lib (see "BruteFIR" for one
>>example, "pconvolve" opcode in Csound for another).
>>
>>
>>Richard Dobson
>>
>>
>>
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>
>
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