>From: Takehiro Tominaga <[EMAIL PROTECTED]>
>
>>>>>> "E" == Erik de Castro Lopo <[EMAIL PROTECTED]> writes:
>
> E> How much double precision floating point code does LAME use?
>
>IMHO, double precision is over spec for MP3 encoder/decoder. For
>example, mpg123 uses only float(single precision).
>
>An input file (like .wav file) has only 16 bit precision and dynamic
>range(this value is selected from human hearing ability). And the
>IEEE768 says single precision has 24 bit precision.
>
>Current release of lame is mixed use of FLOAT(=float) and double.
>I think this is not good because it takes type conversion.
>
>See my version of lame. I changed all "double" into "FLOAT".
>And we can select FLOAT from double and float depending on your
>architechture. I think some architechtuer, like ALPHA chip, we will
>get faster conversion defining FLOAT as double. On my linuxbox with
>celeron 464MHz, I got about 10% speedup from defining FLOAT as float.
AFAIK , C compilers do all floating point operations with doubles,
even when adding two floats they are converted to doubles and then
the result is converted back to float, so using doubles should be faster,
but modern compilers may behave differently.
--
David Balazic , student
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