[FFmpeg-devel] [PATCH] QCELP decoder

Michael Niedermayer michaelni
Tue Dec 2 00:18:11 CET 2008


On Mon, Dec 01, 2008 at 03:00:49PM -0800, Kenan Gillet wrote:
> 
> On Dec 1, 2008, at 2:05 PM, Michael Niedermayer wrote:
> 
> > On Mon, Dec 01, 2008 at 12:45:09PM -0800, Kenan Gillet wrote:
> >> Hi,
> >> On Mon, Dec 1, 2008 at 8:24 AM, Michael Niedermayer  
> >> <michaelni at gmx.at> wrote:
> >>> On Mon, Dec 01, 2008 at 08:17:52AM -0800, Kenan Gillet wrote:
> >>>>
> >>>> On Dec 1, 2008, at 4:52 AM, Michael Niedermayer wrote:
> >>>>
> >>>>> On Sun, Nov 30, 2008 at 05:04:07PM -0800, Kenan Gillet wrote:
> >>>>>> Hi,
> >>>>>> On Nov 30, 2008, at 7:50 AM, Michael Niedermayer wrote:
> >>>>>>
> >>>>>>> On Sat, Nov 29, 2008 at 10:39:58AM -0800, Kenan Gillet wrote:
> >>> [...]
> >>>>> [...]
> >>>>>>>> +    /**
> >>>>>>>> +     * reserved bits on all bitrate but bitrate 1/2 packets
> >>>>>>>
> >>>>>>> this is unclear, field that is on all but ... , vs. field that
> >>>>>>> exists always but
> >>>>>>> is reserved on all but .....
> >>>>>>>
> >>>>>>
> >>>>>> is "reserved bits only set for bitrate 1, 1/4 and 1/8" better ?
> >>>>>
> >>>>> no, because setting them means error IIRC
> >>>>> also IIRC there is no indication of the existence of other fields
> >>>>> for the
> >>>>> other rates ...
> >>>>>
> >>>>
> >>>> reserved bits only present in bitrate 1, 1/4 and 1/8 packets
> >>>>
> >>>> ?
> >>>
> >>> ok
> >>>
> >>> [...]
> >>
> >> here is an updated round 14 of the patches,
> >> which is getting smaller and smaller :)
> >>
> >> Kenan
> >
> > [...]
> >
> >> +/**
> >> + * initial coefficient to perform bandwidth expansion on LPC
> >> + *
> >> + * TIA/EIA/IS-733 2.4.3.3.6 6
> >> + */
> >
> >> +#define QCELP_BANDWITH_EXPANSION_COEFF 0.9883
> >
> > i suspect that is supposed to be an approximation of 253/256
> 
> probably but in specs and reference code it is 0.9883 not 0.98828125.
> do you want to replace 0.9883 by 253/256 ?

no, but it could be added in a comment

[...]
> also I am interested to know if u had any comments on the benchmarks [1]
> between old double vs old float
> and new double vs new float

no comment :)

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

It is not what we do, but why we do it that matters.
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