MixMasterAIAudio Merger
Drop two or more audio files. Reorder them. Set an optional crossfade between adjacent tracks. The merger decodes each one, resamples mismatched files to a common rate, and writes a single WAV. Useful for assembling a mixtape, joining podcast segments, building a continuous soundtrack, or stitching parts of a recording back together after editing.
How it works
Drop the files
Any number, any combination of formats — MP3, WAV, FLAC, OGG, M4A, AAC, AIFF. Reorder with the up/down arrows after dropping.
Up to 200 MB per file
Set the crossfade
0 ms = hard cuts between tracks. 100-500 ms hides the seam between songs in a mixtape. 2-5 s for DJ-style smooth transitions. The crossfade applies between every adjacent pair.
Method: equal-power crossfade
Merge
If files have mismatched sample rates, the merger resamples them to the first file's rate using OfflineAudioContext. Output is a single 16-bit WAV containing all of them spliced into one timeline.
Output: 16-bit WAV at first track's sample rate
Frequently asked questions
Can I mix file formats?
Yes. The browser decodes each format natively (MP3, WAV, FLAC, OGG, M4A, AAC, AIFF), and the merger combines the decoded audio. The output is always WAV — encoding to MP3 happens separately if needed.
What happens with mismatched sample rates?
The merger picks the first file's sample rate as the canonical rate, then resamples the rest to match using OfflineAudioContext. The result is a single coherent file at one consistent rate. There's no audible artifact from this resampling within the supported range (44.1 kHz to 96 kHz).
How long should crossfade be?
For mixing two different songs in a continuous playback (mixtape, radio show), 100-500 ms hides the seam without losing the start of the next track. For DJ blends within compatible keys/tempos, 2-5 seconds gives smooth musical transitions. For rejoining clips of the same recording (podcast edits), 0-50 ms is typically enough.
Why does merger use crossfade equal-power instead of linear?
Equal-power crossfade keeps the perceived loudness constant across the transition. Linear crossfade dips at the midpoint by 3 dB, creating an audible volume drop. For most music applications, equal-power is the right default.