Downmixing two channels?

Hi all,

quick question… If I have a stereo file which I want to downmix to mono (i.e. mono = left + right), do I need to use two ChannelRemappingAudioSource (ch1->ch1, ch2->ch1) and then mix these two with a MixerAudioSource?

I was hoping the ChannelRemappingAudioSource would do the mixing for me, but it looks like it doesn’t (or am I wrong?)


  • bram

Not sure about the ChannelRemappingAudioSource, but you could use an AudioSampleBuffer to do it.

Be aware that simply adding together the channels will not produce correct results unless there is exactly zero correlation between the channels. Since this is presumably a stereo recording, the correlation coefficient will be very high.

Further reading:

I have a whole chain of various AudioSource processors, so I’d rather keep using them.

No worries guys, I know why I’m downmixing and what the pitfalls are…

  • Bram

FYI the ChannelRemappingAudioSource does the job just nicely.
Just need to set it up as:

channelRemapper.setInputChannelMapping(0, 0);
channelRemapper.setInputChannelMapping(1, 1);
channelRemapper.setOutputChannelMapping(0, 0);
channelRemapper.setOutputChannelMapping(1, 0);

Using two AudioSource’s that feed from one audiosource is definitely not a good idea as they will read consecutively and all weird things start to happen…

  • Bram