The most common case is when a microphone or instrument was recorded with the channels reversed — what was L appears in R and vice versa. This happens with inverted TRS cables, interfaces with crossed outputs, or third-party stems with incorrect panning. A simple L↔R swap fixes the issue without any degradation.
Audio Channel Swapper
Swap, duplicate or invert stereo channels with per-channel level analysis and real-time preview.
Stereo audio channels, polarity, and phase correction in practice
Stereo audio files have two independent channels: left (L) and right (R). In production and post-production, common issues include swapped channels (inverted interface output), content recorded with opposite polarity, or the need to force mono on a specific side. This tool operates directly on the PCM samples: decodes the audio, reorganizes channels according to the chosen operation, and exports. No data is sent to the server.
Analyze, choose an operation, and export
- Upload your audio file and review the peak level, RMS, and correlation for each channel.
- Choose an operation: swap L↔R, duplicate one side to both channels, or invert polarity.
- Listen to the preview, adjust if needed, and export in your chosen format.
Sources and references for this tool
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
- AudioBuffer.getChannelData() — Web APIsMDN Web Docs — Method to access PCM data for a specific channel — foundation for channel swap and inversion.
- Phase and Polarity in Audio EngineeringWikipedia — Wave phase concept — essential for understanding channel polarity inversion in audio.
- Web Audio API Specification — AudioBufferW3C / WebAudio Working Group — Formal AudioBuffer specification — defines channel structure and PCM sample access.