[FFmpeg-devel] [PATCH] do not hardcode filter order in ff_acelp_lspd2lpc()

Michael Niedermayer michaelni
Sun Nov 8 01:00:10 CET 2009


On Sat, Nov 07, 2009 at 06:09:07PM +0100, Vitor Sessak wrote:
> Michael Niedermayer wrote:
>> On Sat, Nov 07, 2009 at 12:03:39AM +0100, Vitor Sessak wrote:
>>> Michael Niedermayer wrote:
>>>> On Thu, Nov 05, 2009 at 05:36:36AM +0100, Vitor Sessak wrote:
>>>>> Reynaldo H. Verdejo Pinochet wrote:
>>>>>> Hello Vitor
>>>>>> Vitor Sessak wrote:
>>>>>>> $subj. It is useful for SIPR but also it makes sense to make shared
>>>>>>> functions as general as possible.
>>>>>> QCELP part is ok but I'd make lp_half_order
>>>>>> a single-byte sized type.
>>>>> Fine for me (I suppose comparing uint8_t with int is not slower in any 
>>>>> arch we support). New version attached.
>>>>>
>>>>> -Vitor
>>>>>  lsp.c      |   12 ++++++------
>>>>>  lsp.h      |    2 +-
>>>>>  qcelpdec.c |    2 +-
>>>>>  3 files changed, 8 insertions(+), 8 deletions(-)
>>>>> 4c16615dbbd30c5ab006c8da8b879ea577097b39  lspd2lpc_2.diff
>>>>> Index: libavcodec/lsp.c
>>>>> ===================================================================
>>>>> --- libavcodec/lsp.c	(revision 20450)
>>>>> +++ libavcodec/lsp.c	(working copy)
>>>>> @@ -155,20 +155,20 @@
>>>>>      }
>>>>>  }
>>>>>  -void ff_acelp_lspd2lpc(const double *lsp, float *lpc)
>>>>> +void ff_acelp_lspd2lpc(const double *lsp, float *lpc, uint8_t 
>>>>> lp_half_order)
>>>>>  {
>>>>> -    double pa[6], qa[6];
>>>>> +    double pa[lp_half_order+1], qa[lp_half_order+1];
>>>>>      int   i;
>>>>>  -    lsp2polyf(lsp,     pa, 5);
>>>>> -    lsp2polyf(lsp + 1, qa, 5);
>>>>> +    lsp2polyf(lsp,     pa, lp_half_order);
>>>>> +    lsp2polyf(lsp + 1, qa, lp_half_order);
>>>>>  -    for (i=4; i>=0; i--)
>>>>> +    for (i=lp_half_order-1; i>=0; i--)
>>>>>      {
>>>>>          double paf = pa[i+1] + pa[i];
>>>>>          double qaf = qa[i+1] - qa[i];
>>>>>           lpc[i  ] = 0.5*(paf+qaf);
>>>>> -        lpc[9-i] = 0.5*(paf-qaf);
>>>>> +        lpc[(lp_half_order << 1) - 1 -i] = 0.5*(paf-qaf);
>>>>>      }
>>>> i would
>>>> lpc2= lpc + (lp_half_order << 1) - 1;
>>>> and
>>>> lpc2[-i] = ...
>>>> that way lp_half_order and i also become redundant and one can be droped
>>>> about int8 vs. int, its possible that using int8 as index into an array
>>>> like lpc[int8_variable] could be slower in some archs (x86 being one)
>>> Since pa[] is an array not a pointer I cannot do the 
>>> while(lp_half_order--) { (...) pa++; ga++; lpc++; lpc2--;} trick not to 
>>> use the var "i" (and the other option would use lpc[int8_var]). In this 
>>> new version I've also made the loop count forward to make it more 
>>> readable.
>> you could change lp_half_order back to int if reynaldo doesnt mind.
>> i think that would avoid the problem?
>
> Yes, new patch attached.
>
> -Vitor

>  lsp.c      |   21 ++++++++++-----------
>  lsp.h      |    2 +-
>  qcelpdec.c |    2 +-
>  3 files changed, 12 insertions(+), 13 deletions(-)
> f232b1334e175b5427aa5642576cfb3c1adff534  lspd2lpc_4.diff

iam ok with the things iam maintainer for

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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