[RFC SBC] build: Add configure option --disable-high-precision

[RFC SBC] build: Add configure option --disable-high-precision

[Luiz Augusto von Dentz]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

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 */
 
 #ifdef SBC_HIGH_PRECISION
-- 
1.8.3.1

Re: [RFC SBC] build: Add configure option --disable-high-precision

[Marcel Holtmann]

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.

Regards

Marcel

Re: [RFC SBC] build: Add configure option --disable-high-precision

[Luiz Augusto von Dentz]

Hi Marcel,

On Mon, Sep 16, 2013 at 5:19 PM, Marcel Holtmann <marcel@holtmann.org> 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