Thanks a lot
Something like Z = A + B -A.B/normaliztion value
On 9/24/07, Alan Horstmann <gineera@xxxxxxxxxxxxxxx> wrote:
> On Monday 24 September 2007 12:49, Claudio Matsuoka wrote:
> > On 9/24/07, Nobin Mathew <nobin.mathew@xxxxxxxxx> wrote:
> > > Can any body throw some lights on how audio mixing is done in
> > > software? Basic principle?
> >
> > Basically you add the PCM samples (if they are at the same resolution
> > and sampling rate) and renormalize if needed. The sampling rate
> > conversion can be tricky tho.
>
> I was about to say the same; multiply each sample by the applicable gain and
> add - as in this extract from Audacity/src/AudioIO.cpp:
>
> {
>
> if (vt->GetChannel() == Track::LeftChannel ||
> vt->GetChannel() == Track::MonoChannel)
> {
> float gain = vt->GetChannelGain(0);
>
> if (gAudioIO->mEmulateMixerOutputVol)
> gain *= gAudioIO->mMixerOutputVol;
>
> for(i=0; i<len; i++)
> outputFloats[numPlaybackChannels*i] += gain*tempFloats[i];
> }
>
> if (vt->GetChannel() == Track::RightChannel ||
> vt->GetChannel() == Track::MonoChannel)
> {
> float gain = vt->GetChannelGain(1);
>
> if (gAudioIO->mEmulateMixerOutputVol)
> gain *= gAudioIO->mMixerOutputVol;
>
> for(i=0; i<len; i++)
> outputFloats[numPlaybackChannels*i+1] += gain*tempFloats[i];
> }
> }
>
> I guess implementing it is always more complicated, though!
>
> Alan
>
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
