[FFmpeg-devel] [PATCH] Common ACELP routines - pitch lag decoding

[Michael Niedermayer]

On Sun, Apr 27, 2008 at 07:08:10PM +0700, Vladimir Voroshilov wrote:
> On Sun, Apr 27, 2008 at 6:41 PM, Diego Biurrun <diego at biurrun.de> wrote:
> > On Sun, Apr 27, 2008 at 06:11:50PM +0700, Vladimir Voroshilov wrote:
> >  >
> >  > Here is another small set of routines which can be shared between
> >  > AMR (even with floating point) and G.729.
> >  >
> >  > --- /dev/null
> >  > +++ b/libavcodec/acelp_pitch_lag.h
> >  > @@ -0,0 +1,175 @@
> >  > + *
> >  > + * From G.729 psecification:
> >
> >  specification
> 
> Fixed.
> 
> >  > + * This range is adapted for the cases where T1 straddles the boundaries of the
> >  > + * delay range [20; 143].
> >
> >  What do you mean by "straddles" here?
> 
> This is exact phrase from specification.
> I read it as "This range is adapted to completely fit into delay range
> [20; 143]"
> 
> >
> >  > + * \param subframeno subframe number (0 - 1st,3rd subframes; 1 - 2nd,4th subframes)
> >
> >  Add spaces after the commas please.
> 
> Done


[...]
> +void ff_acelp_decode_lag3_8_4_bits(
> +        int* pitch_lag_int,
> +        int* pitch_lag_frac,
> +        int ac_index,
> +        int subframeno,
> +        int pitch_lag_min)
> +{
> +    // (4.1.3 of G.729 and 5.6.1 of AMR)
> +    if (!subframeno)
> +    {
> +        if(ac_index < 197)
> +        {
> +            *pitch_lag_frac = (ac_index + 2)%3 - 1;
> +            *pitch_lag_int  = (ac_index + 2)/3 + 19;
> +        }
> +        else
> +        {
> +            *pitch_lag_int = ac_index - 112;
> +            *pitch_lag_frac = 0;
> +        }
> +    }
> +    else
> +    {
> +        ac_index &= 0xf;
> +
> +        if(ac_index < 4)
> +        {
> +            *pitch_lag_frac = 0;
> +            *pitch_lag_int  = ac_index;
> +        }
> +        else if(ac_index < 12)
> +        {
> +            *pitch_lag_frac = (ac_index + 1)%3 - 1;
> +            *pitch_lag_int  = (ac_index + 1)/3 + 2;
> +        }
> +        else
> +        {
> +            *pitch_lag_frac = 0;
> +            *pitch_lag_int = ac_index - 6;
> +        }
> +
> +        *pitch_lag_int += pitch_lag_min;
> +    }
> +}

Is this simpler if the frac/int split is factored out?
If (and only if) its simpler then please split it out. That is have the
%3 /3 at the end outside all if/else



> +
> +void ff_acelp_decode_lag3_8_56_bits(
> +        int* pitch_lag_int,
> +        int* pitch_lag_frac,
> +        int ac_index,
> +        int subframeno,
> +        int pitch_lag_min)
> +{
> +    // (4.1.3 of G.729 and 5.6.1 of AMR)
> +    if (!subframeno)
> +    {
> +        if(ac_index < 197)
> +        {
> +            *pitch_lag_frac = (ac_index + 2)%3 - 1;
> +            *pitch_lag_int  = (ac_index + 2)/3 + 19;
> +        }
> +        else
> +        {
> +            *pitch_lag_int  = ac_index - 112;
> +            *pitch_lag_frac = 0;
> +        }
> +    }

duplicate

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

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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