How to use
- Choose one or more audio files (videos work too — their sound is used).
- Choose M4A or WAV, and tick Reverse or set the number of repeats if needed.
- Click Convert and download; several files download as a ZIP.
Options explained
- Output formats
- M4A (AAC, 192 kbps) is small and plays almost everywhere; WAV is lossless and large, best for editing.
- Reverse and loop
- Reverse plays the whole sound backwards; Repeat joins the audio end to end up to 20 times.
Expected file sizes
M4A is encoded at 192 kbps, so its size depends only on the length: 192,000 bits per second is 24,000 bytes per second, or about 1.4 MB per minute. WAV is written as 16-bit PCM at the sample rate of the source, so its size is:
bytes per second = sample rate × channels × 2For a 44.1 kHz stereo file that is 176,400 bytes per second, about 10.6 MB per minute, roughly seven times larger than the M4A. A 4-minute song comes to about 5.8 MB as M4A and 42 MB as WAV. When Repeat is set, the length, and so the size, is multiplied by the number of repeats.
Frequently asked questions
Why no MP3 output?
Browsers can't encode MP3. M4A sounds better at a smaller size and is supported almost everywhere.
Does converting lose quality?
Not to WAV. M4A compresses once, which is usually inaudible. Converting a lossy file to WAV won't make it better.
Are my files uploaded?
No. Everything happens in your browser.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.