Hi Marcel,
On Mon, Sep 16, 2013 at 5:19 PM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
> Hi Luiz,
>
>> This enables high precision using 64 bits accumulators by default which
>> can be disabled with --disable-high-precision.
>> ---
>> configure.ac | 8 ++++++++
>> sbc/sbc_tables.h | 2 --
>> 2 files changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/configure.ac b/configure.ac
>> index c052616..5f994d1 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -58,4 +58,12 @@ if (test "${enable_tester}" != "no"); then
>> fi
>> AM_CONDITIONAL(TESTER, test "${enable_tester}" != "no")
>>
>> +AC_ARG_ENABLE(high-precision, AC_HELP_STRING([--disable-high-precision],
>> + [disable high precision support]),
>> + [enable_high_precision=${enableval}])
>> +if (test "${enable_high_precision}" != "no"); then
>> + AC_DEFINE(SBC_HIGH_PRECISION, 1,
>> + [Define to 1 to enable high precision build of SBC encoder])
>> +fi
>> +
>> AC_OUTPUT(Makefile sbc/sbc.pc)
>> diff --git a/sbc/sbc_tables.h b/sbc/sbc_tables.h
>> index 25e24e6..3fd80e1 100644
>> --- a/sbc/sbc_tables.h
>> +++ b/sbc/sbc_tables.h
>> @@ -136,8 +136,6 @@ static const int32_t synmatrix8[16][8] = {
>> SN8(0xfb8e3130), SN8(0xf8275a10), SN8(0xfe70747c), SN8(0x06a6d988) }
>> };
>>
>> -/* Uncomment the following line to enable high precision build of SBC encoder */
>> -
>> /* #define SBC_HIGH_PRECISION */
>
> the comment with the define should also be removed.
>
> Is there any impact on using 64-bit integers compared to 32-bit integers. When would you use one or the other. I think this needs to be documented in README as well.
The use of 64-bit apparently makes the encoder 'better' in term of
dynamic range, but I will probably check with the tools that Siarhei
uses for testing the exact amount of 'better', the drawback is that
for 32-bits systems it might have an impact in performance so it is
good to keep --disable-high-precision and document it in the README as
you suggested.
Maybe this will be useful to kick start some unit tests for sbc as well.
--
Luiz Augusto von Dentz
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