Wav File

Hi 

I reading a Wav file in C++. I need to convert the PCM values to float
values for further DSP manipulation (Filtering etc ...). Do I need to do
this through a conversion from Hex to binary unsigned 2 complement values
then to integers ? Thus anyone know of any available function in C/C++ ? Am
I missing something ?

Thanks and Regards
Aaron 

aaronde wrote:
> Hi 
> 
> I reading a Wav file in C++. I need to convert the PCM values to float
> values for further DSP manipulation (Filtering etc ...). Do I need to do
> this through a conversion from Hex to binary unsigned 2 complement values
> then to integers ? Thus anyone know of any available function in C/C++ ? Am
> I missing something ?

I suspect that you are in serious trouble if you don't know that hex and 
binary represent exactly the same thing.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

aaronde wrote:

> Hi 
> 
> I reading a Wav file in C++. I need to convert the PCM values to float
> values for further DSP manipulation (Filtering etc ...). Do I need to do
> this through a conversion from Hex to binary unsigned 2 complement values
> then to integers ? Thus anyone know of any available function in C/C++ ? Am
> I missing something ?

Sometimes the idiocy of modern programmers is just unbelievable.

VLV

>
>
>aaronde wrote:
>
>> Hi 
>> 
>> I reading a Wav file in C++. I need to convert the PCM values to float
>> values for further DSP manipulation (Filtering etc ...). Do I need to
do
>> this through a conversion from Hex to binary unsigned 2 complement
values
>> then to integers ? Thus anyone know of any available function in C/C++
? Am
>> I missing something ?
>
>Sometimes the idiocy of modern programmers is just unbelievable.
>
>VLV
>

Hi

Thanks for calling me an idiot. Really nice of you I suppose you were born
knowing everything and you never asked a simple and dumb question. No one
forced you to reply or read the post if you think it so stupid. On the
other hand I would appreciate any help as this is the first time I am doing
such work.

Okey I know that hex and binary are the representation of the same thing.
My question was that you can't apply a dsp operation using the PCM values.
If I read the wav file and get a Hex value of 8A  this has to be
represented as an float type ie conveted and rescaled to a range between -1
and 1 in order to apply further operations. My question was weather there
is a built in fucntion in C/C++. Please excuse me if I am not clear with my
question 

Thanks and Regards
Aaron 

aaronde wrote:
>>
>> aaronde wrote:
>>
>>> Hi 
>>>
>>> I reading a Wav file in C++. I need to convert the PCM values to float
>>> values for further DSP manipulation (Filtering etc ...). Do I need to
> do
>>> this through a conversion from Hex to binary unsigned 2 complement
> values
>>> then to integers ? Thus anyone know of any available function in C/C++
> ? Am
>>> I missing something ?
>> Sometimes the idiocy of modern programmers is just unbelievable.
>>
>> VLV
>>
> 
> Hi
> 
> Thanks for calling me an idiot. Really nice of you I suppose you were born
> knowing everything and you never asked a simple and dumb question. No one
> forced you to reply or read the post if you think it so stupid. On the
> other hand I would appreciate any help as this is the first time I am doing
> such work.
> 
> Okey I know that hex and binary are the representation of the same thing.
> My question was that you can't apply a dsp operation using the PCM values.
> If I read the wav file and get a Hex value of 8A  this has to be
> represented as an float type ie conveted and rescaled to a range between -1
> and 1 in order to apply further operations. My question was weather there
> is a built in fucntion in C/C++. Please excuse me if I am not clear with my
> question 
> 
> Thanks and Regards
> Aaron 


You need to use either the plain assignment operator or a cast.

short number = 55;
double dnumber = number;
-- or --
double dnumber = (double) number;
depending on which sort of compiler you use and
what options are enabled.

--
Les Cargill

aaronde wrote:
>>
>> aaronde wrote:
>>
>>> Hi 
>>>
>>> I reading a Wav file in C++. I need to convert the PCM values to float
>>> values for further DSP manipulation (Filtering etc ...). Do I need to
> do
>>> this through a conversion from Hex to binary unsigned 2 complement
> values
>>> then to integers ? Thus anyone know of any available function in C/C++
> ? Am
>>> I missing something ?
>> Sometimes the idiocy of modern programmers is just unbelievable.
>>
>> VLV
>>
> 
> Hi
> 
> Thanks for calling me an idiot. Really nice of you I suppose you were born
> knowing everything and you never asked a simple and dumb question. No one
> forced you to reply or read the post if you think it so stupid. On the
> other hand I would appreciate any help as this is the first time I am doing
> such work.
> 
> Okey I know that hex and binary are the representation of the same thing.
> My question was that you can't apply a dsp operation using the PCM values.

If course you can. It's called "integer". Often you need to scale it. 
See especially http://www.digitalsignallabs.com/fp.pdf and also 
http://cnx.org/content/m11054/latest/

> If I read the wav file and get a Hex value of 8A  this has to be
> represented as an float type ie conveted and rescaled to a range between -1
> and 1 in order to apply further operations. My question was weather there
> is a built in fucntion in C/C++. Please excuse me if I am not clear with my
> question 

I'll go put on a limb and claim that every language that supports both 
integer and floating point has a way to convert between them. In C and 
C++, the compiler will do it for you if you ask nicely.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On Thu, 12 Nov 2009 22:29:53 -0600, aaronde wrote:

> If I read the wav file and get a Hex value of 8A  this has to be
> represented as an float type ie conveted and rescaled to a range between
> -1 and 1 in order to apply further operations.

I was going to try to be helpful, but then I noticed that your question 
contained the entire answer (above).  So now I'm just confused about what 
it is that you don't understand.  Could you have another go at asking the 
question, please?

Cheers,

-- 
Andrew

On 11/12/2009 9:29 PM, aaronde wrote:
>>
>> aaronde wrote:
>>
>>> Hi
>>>
>>> I reading a Wav file in C++. I need to convert the PCM values to float
>>> values for further DSP manipulation (Filtering etc ...). Do I need to
> do
>>> this through a conversion from Hex to binary unsigned 2 complement
> values
>>> then to integers ? Thus anyone know of any available function in C/C++
> ? Am
>>> I missing something ?
>> Sometimes the idiocy of modern programmers is just unbelievable.
>>
>> VLV
>>
>
> Hi
>
> Thanks for calling me an idiot. Really nice of you I suppose you were born
> knowing everything and you never asked a simple and dumb question. No one
> forced you to reply or read the post if you think it so stupid. On the
> other hand I would appreciate any help as this is the first time I am doing
> such work.
>
> Okey I know that hex and binary are the representation of the same thing.
> My question was that you can't apply a dsp operation using the PCM values.

First, that's not a question, and, second, it's not true.

Why can't you do a DSP operation on integers?

> If I read the wav file and get a Hex value of 8A  this has to be
> represented as an float type ie conveted and rescaled to a range between -1
> and 1 in order to apply further operations.

I don't know why that would be.  Lots of processing is done on arrays or 
streams of integers without ever converting to floating point.

> My question was weather there
> is a built in fucntion in C/C++. Please excuse me if I am not clear with my
> question
>
> Thanks and Regards
> Aaron


-- 
Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.abineau.com

aaronde wrote:

> Hi 
> 
> I reading a Wav file in C++. I need to convert the PCM values to float
> values for further DSP manipulation (Filtering etc ...). Do I need to do
> this through a conversion from Hex to binary unsigned 2 complement values
> then to integers ? Thus anyone know of any available function in C/C++ ? Am
> I missing something ?

You're probably much more interesting in doing the DSP manipulation
than you are in reading WAV files. If thats the case, then why don't
you use libsndfile:

    http://www.mega-nerd.com/libsndfile/

which reads WAV as well as many other formats. In addition, if you
can use the sf_read_float() function you can directly read normalized 
floating point data

    http://www.mega-nerd.com/libsndfile/api.html#read

Ie the library does the conversion to float for you, on the fly.

Erik
-- 
----------------------------------------------------------------------
Erik de Castro Lopo
http://www.mega-nerd.com/

aaronde wrote:
>>
>>aaronde wrote:
>>
>>
>>>I reading a Wav file in C++. I need to convert the PCM values to float
>>>values for further DSP manipulation

>>Sometimes the idiocy of modern programmers is just unbelievable.
> 
> Thanks for calling me an idiot. 

Sure. I can call you idiot once more, if you like.

> Really nice of you I suppose you were born
> knowing everything and you never asked a simple and dumb question.

You see, before I could do any programming, I had to build a computer 
for myself.  With soldering iron, breadboard and discrete parts from 
black market. There wasn't anybody to ask questions to. Now, with the 
computers widely available, with the miracles of Google and Wikipedia, 
with the zillion of books and online guides, why do you have to ask 
2+2=4 question?

VLV