[FFmpeg-devel] AMR-NB decoder

[Colin McQuillan]

Reynaldo, Robert, could you review your parts of this patch please? I
checked the QCELP ref decoder before writing the comment.

2009/8/10 Michael Niedermayer <michaelni at gmx.at>:
> On Mon, Aug 10, 2009 at 08:42:53AM +0100, Colin McQuillan wrote:
>> 2009/8/9 M?ns Rullg?rd <mans at mansr.com>:
>> > Colin McQuillan <m.niloc at googlemail.com> writes:
>> >
>> >> 2009/8/8 Michael Niedermayer <michaelni at gmx.at>:
>> >>> On Sat, Aug 08, 2009 at 04:09:39PM +0100, Colin McQuillan wrote:
>> >>>> 2009/8/8 Michael Niedermayer <michaelni at gmx.at>:
>> >>>> > On Fri, Aug 07, 2009 at 08:23:53PM +0100, Colin McQuillan wrote:
>> >>>> >> 2009/8/6 Michael Niedermayer <michaelni at gmx.at>:
>> >>>> >> > On Wed, Aug 05, 2009 at 05:51:36PM +0100, Colin McQuillan wrote:
>> >>>> >> >> Attached is a patch for an AMR-NB decoder.
>> >>>>
>> >>>> [...]
>> >>>>
>> >>>> >> > that should e a seperate patch
>> >>>> >>
>> >>>> >> I'll leave this one until I investigate a version for sparse vectors. Attached:
>> >>>> >>
>> >>>> >> 1. Helper functions for gain control in floating-point codecs
>> >>>> >> I couldn't find a similar fixed point function to copy the function name.
>> >>>> >>
>> >>>> >> 2. Floating-point version of ff_acelp_high_pass_filter
>> >>>> >
>> >>>> >> ?acelp_vectors.c | ? 22 ++++++++++++++++++++++
>> >>>> >> ?acelp_vectors.h | ? 27 +++++++++++++++++++++++++++
>> >>>> >> ?2 files changed, 49 insertions(+)
>> >>>> >> f1abbee9b62c1779fd5fb1c634d4ab4294d8611d ?get-set-energyf.patch
>> >>>> >> Index: libavcodec/acelp_vectors.c
>> >>>> >> ===================================================================
>> >>>> >> --- libavcodec/acelp_vectors.c ? ? ? ?(revision 19606)
>> >>>> >> +++ libavcodec/acelp_vectors.c ? ? ? ?(working copy)
>> >>>> >> @@ -155,3 +155,25 @@
>> >>>> >> ? ? ? ? ?out[i] = weight_coeff_a * in_a[i]
>> >>>> >> ? ? ? ? ? ? ? ? + weight_coeff_b * in_b[i];
>> >>>> >> ?}
>> >>>> >> +
>> >>>> >> +float ff_energyf(const float *v, int length)
>> >>>> >> +{
>> >>>> >> + ? ?float sum = 0;
>> >>>> >> + ? ?int i;
>> >>>> >> +
>> >>>> >> + ? ?for (i = 0; i < length; i++)
>> >>>> >> + ? ? ? ?sum += v[i] * v[i];
>> >>>> >> +
>> >>>> >> + ? ?return sum;
>> >>>> >> +}
>> >>>> >
>> >>>> > ff_dot_productf)(
>> >>>>
>> >>>> Do you mean that ff_energyf is redundant? I've taken it out.
>> >>>
>> >>> hmm well, as you say it that way, ff_energyf() could be faster due to
>> >>> fewer mem reads, if that is te case in practice it could be kept
>> >>
>> >> ff_energyf is reliably 4% faster in my test, so I'll add it back in.
>> >
>> > That function has high simdicity so it should be added to dsputil and
>> > simdified.
>>
>> I'll try, but I didn't mean to imply that energy calculations are
>> critical to performance. The slow parts of the AMR decoder are the IIR
>> and FIR filters, which are already in celp_filters.c.
>
> if the SIMD energy is not reaching an overall (whole codec) 0.1% speedup over
> using a more generic SIMD dot product then its probably not worth it and
> could be ommited

Great! Then I'll leave out ff_energyf, and avoid using "length" in the comments.

[...]

> alignment requirements are supposed to be written liks:
> void ff_vp3_idct_put_c(uint8_t *dest/*align 8*/, int line_size, DCTELEM *block/*align 16*/);
> also "/*" is not doxygen compatible and what the function does should be
> more verbosely described, energy isnt a mathematically clear term, dot
> product and sum or squares are.
>

Changed.
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