[FFmpeg-devel] [PATCH] Common ACELP routines (2/3) - filters

[Vladimir Voroshilov]

On Sun, Apr 27, 2008 at 12:41 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Sat, Apr 26, 2008 at 11:11:56PM +0700, Vladimir Voroshilov wrote:
>
> > On Fri, Apr 25, 2008 at 6:16 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>  >
>  > [...]
>  >
>  > >  Yes thats also what i thought at first but vladimirs insistance made
>  > >  me belive that the output of this function would be the final audio
>  > >  samples returned from "decode_audio". In which cases one of course
>  > >  cannot have 10 samples before it.
>  > >  Now after looking at the actual code its clear that there are always
>  > >  some other filters applied afterwards. So i agree, none of this makes
>  > >  sense, no double writing, no special case for the first "10" samples
>  > >  nor a memcpy() should be needed. Except a memcpy to move the first
>  > >  "10" samples to the buffer start.
>  >
>  > To tell the truth i didn't understand should i fix patch somehow or
>  > not according to above.
>
>  ff_acelp_lp_synthesis_filter_inplace() is exactly what we need,
>  ff_acelp_lp_synthesis_filter() is unneeded, please remove it.
>
>
>
>  >
>  > After splitting ff_acelp_lp_synthesis_filter, one of routines still
>  > requires additional 10 items in filter data. It is possible to avoid
>  > such requirement in cost of additional 20 bytes long memcpy.
>  > But i don't know will this improve something or not.
>
>  Only a single memcpy() of 10 elements is needed.
>
>  memcpy(buf, buf+N, 10);
>  overflow= acelp_lp_synthesis_filter(buf+10, input, N);
>  if(overflow){
>     for(i=0; i<N; i++)
>         input[i]>>=123;
>     acelp_lp_synthesis_filter(buf+10, input, N);
>  }

buf is subframe_size+10 long as i see.
And this will require copy from buf to output_data
(explicit via memcpy or implicit, e.g. high-pass filter should put
data directly to output_data instead of it's input buffer)
Second is preferred, right?

>
>  Ill review the rest later

Get updated patch from my reply to Diego's mail.
I want to hear your opinion about math-related comments as well.

-- 
Regards,
Vladimir Voroshilov mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
ICQ: 95587719