Re: Change output volume



On Wed, 5 Apr 2006 04:49:30 +0200, Lis wrote:

In article <1bs4797tatdl1$.15bwhzi4lkle1$.dlg@xxxxxxxxxx>,
msdn@xxxxxxxxxxxx says...
On Tue, 4 Apr 2006 16:28:45 +0200, Lis wrote:

Can someone help me with amplify output volumes?
I only want to know wheather i can do that with
some directx api functions or need to hardcode it.

DirectX allows volume reduction only. To amplify you will have to modify
the samples before or as they are copied to the buffer. For example
multiplying each sample by 2 will increase the output 6 dB. Do have to
take care of clipping by limiting the output to the sample size maximums,
i.e. -32768, +32767 for 16-bit.


Is this result raise in squares?

I. e. mutiply with 4 gets 24dB boost?

No linear. Multiply by 4 gives 12dB gain. Of course you can multiply by
decimal fractions as well to get anything in between. If you search this
group or microsoft.public.win32.programmer.mmedia you should find the
conversion formulas I have previously posted.

--
http://www.chrisnet.net/code.htm
http://www.avdevforum.com/AV
.



Relevant Pages

  • Re: Change output volume
    ... some directx api functions or need to hardcode it. ... DirectX allows volume reduction only. ... To amplify you will have to modify ...
    (microsoft.public.win32.programmer.directx.audio)
  • Re: Change output volume
    ... I only want to know wheather i can do that with ... some directx api functions or need to hardcode it. ... DirectX allows volume reduction only. ...
    (microsoft.public.win32.programmer.directx.audio)