[LAD] audio conversion functions

[Jens M Andreasen]

On Wed, 2007-07-18 at 14:55 -0700, Craig Hoedebeck wrote:
> I am relatively new to audio programming, but I have a task that
> requires converting between various audio formats:
> 
> unsigned 16 bit linear to signed 16 bit linear
> u_law to signed 16 bit linear
> a_law to signed 16 bit linear
> unsigned 8 bit linear to signed 16 bit 
> signed 8 bit linear to signed 16 bit
> 
> Anyone know what the conversion functions for these would look like?
> Or even what a good reference is where I can find these?  I have been
> googling around for about an hour and I have come up empty.

For a_law an u_law you could try wikipedia, which will also give you a
nice link for further reading and implementation here:

http://hazelware.luggle.com/tutorials/mulawcompression.html

The linear conversions should be trivial, something like:

// unsigned 16 bit linear to signed 16 bit linear:
   short s_16 = u_16 - 32758

// signed 8 bit linear to signed 16 bit
   short s_16 = s_char << 8

// unsigned 8 bit linear to signed 16 bit
   short s_16 = (u_char - 128) << 8
 

Mind you, i haven't had my coffee yet ...


> 
> 
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