Channel Mixer
Decide exactly how much of each input channel goes to each output channel, including inverted copies.
MP3, WAV, M4A, FLAC, OGG, Opus, AIFF, WMA, AMR and the sound of most videos. Files stay on your device.
How it works
- Choose an audio file.
- Set the gain for each input-to-output pair, and tick Invert where needed.
- Preview the result.
- Export and download.
A 2 by 2 mixing matrix
Each output channel is the sum of the two input channels, each multiplied by a gain. The four sliders set those gains in percent: 100 passes a channel unchanged, 50 is 6 dB quieter, 0 removes it, and a negative value flips its polarity. Left to left and right to right at 100 percent is the unchanged stereo file.
The polarity switches invert a whole input or a whole output channel, which is the quickest way to fix a recording where one microphone was wired out of phase.
Presets
The presets cover the common jobs: sum to mono, swap left and right, put the left or right channel on both sides, flip the right channel’s polarity, and encode or decode mid/side. Mid/side encode puts the sum of the channels on the left and their difference on the right; decode reverses it.
Watch the level
When an output can reach more than 100 percent of the input level the page warns that loud parts may clip. The mixer needs a stereo file and always writes two channels. For other jobs the dedicated tools (stereo to mono, swap, split) are simpler.
Questions
How do I invert the phase of one channel?
Switch on the polarity toggle for that channel, or choose the Flip the right channel polarity preset.
What is mid/side?
Mid is what both channels have in common; side is what differs. Many mixing and mastering tools work on the two separately. The width tool does this for you.
Why does my mono mix sound quieter than the stereo file?
The mono preset averages the channels so it cannot clip. Raise the gains if you want it louder, and check the preview for clipping.
Does it work on files with more than two channels?
No. It needs a stereo file.