MD: Stereo Width Controller

AI-generated music has a signature problem: it often comes out sounding narrow and monophonic, like it was mixed in a phone speaker. MD_Stereo_Width_Controller fixes that with one slider - it processes your audio through mid/side encoding and adjusts how wide the stereo image is, from fully mono (0%) up to extra-wide (200%).

It's the stereo counterpart to the pack's LUFS normalizer: LUFS makes your audio loud enough, this makes it wide enough. Both belong at the end of an audio pipeline, and together they're most of the difference between "that AI track" and "that sounds like it was mastered."

How it works

The node takes the left/right channels, encodes them into mid (L+R) and side (L−R) components, scales the side component by your width setting, and decodes back to left/right. Boosting the side signal widens the image; reducing it narrows toward mono. It's the standard mid/side trick, done correctly on the waveform. If the input is mono, there's no side signal to work with, so the node passes it through untouched - the tooltip flags this explicitly.

The inputs that matter

• width_percent - 0% collapses to mono, 100% is the original width, 110–120% is the subtle-enhancement sweet spot, and up to 200% pushes aggressively wide. The tooltip's warning about phase cancellation above 100% is real: over-widening flips phase on out-of-phase content, and on speakers or headphones that shows up as a hollow, comb-filtered sound. Also keep in mind that when a streamer or platform converts to mono, over-widened content can partially cancel out - another reason to stay restrained.

Output: the processed audio, ready for the save/preview node. debug_mode just controls logging.

Installing

Part of MD Nodes, so the pack install covers it:

cd path/to/ComfyUI/custom_nodes
git clone https://github.com/MDMAchine/ComfyUI_MD_Nodes.git
cd ComfyUI_MD_Nodes
pip install -r requirements.txt

Or ComfyUI Manager → MD Nodes → install → restart. The mid/side math ships in the pack's DSP core; no model downloads.

Common issues

The classic mistakes: widening before you've confirmed the mix is good, and widening by a lot. Stereo width is a polish stage - if the track is already muddy or has phase issues, making it wide just spreads the mud across the room. Check the mix in mono first (width at 0% is a free mono check), fix the fundamentals, then add 10–20% and stop. And the phase-cancellation warning deserves repeating: if your result sounds thin or weird in mono after widening, you've pushed it too far - back the slider off rather than EQ-ing the damage away.