Reversing audio plays every decoded sample from the end of the recording back to its beginning, which is the most common interpretation of an "audio swap" on DistroKid when listeners want to hear a track in reverse. DistroKid's audio swap feature, by contrast, is a release-management tool that replaces the audio file behind an already-distributed track without removing streams or playlist placement, and it does not change the playback direction of the audio itself. Because reversing audio is a sample-level operation rather than a release-management step, it is done locally in your browser before you re-upload the new file to any platform. The Reverse Audio tool reads your chosen MP3, WAV, M4A, AAC, Ogg, or WebM file in the current tab, decodes every channel through the Web Audio API, reverses the sample order in each channel independently, and then writes a freshly encoded PCM16 WAV that you can download immediately. No file bytes leave your device, the Web Audio context is closed after the operation, and the original sample rate and channel count are preserved when they fit the tool's declared limits.
DistroKid's Audio Swap vs. Reversing Audio Playback
DistroKid's audio swap is built for a specific problem: a label, distributor, or artist has already pushed a track to Spotify, Apple Music, and other stores, and they need to replace the underlying audio file because of a mastering error, a vocal fix, or a stem swap. The feature is engineered so that the new audio inherits the existing release's ISRC, stream count, and playlist placement, which makes it the right choice when the goal is platform-level metadata continuity rather than a creative transformation.
Reversing audio is a different problem. It is a sample-level transformation that reads every channel of a decoded recording and writes each sample in reverse order, so that the last sample becomes the first and the first becomes the last. People search for "audio swap" on DistroKid when they actually want a reversed master for a transition effect, a sound-design experiment, reverse speech for a teaser, or a quick way to listen to the end of a recording from a different perspective. For that workflow, the reversed file is produced locally in the browser before you decide whether to upload it anywhere, and DistroKid's release-management feature is not involved at all. The Reverse Audio tool is the practical answer for this interpretation, because it handles the sample-level reversal in the current tab and returns a fresh WAV you can preview, verify, and reuse in any editor.
Reverse an Audio File in Your Browser
- Open the Reverse Audio tool in your current browser tab and click the file picker to choose an MP3, WAV, M4A, AAC, Ogg, or WebM file. The browser checks the MIME type against the supported list and rejects anything larger than 50 MB before reading the bytes.
- If you want to confirm you picked the right source, use the built-in preview to listen to the original file. The preview is created from a temporary local object URL, and that URL is released when you pick a new file or leave the page.
- Select "Reverse audio" and wait while the Web Audio context decodes every channel of the file. The decoded buffer is checked against the five-minute duration cap, the eight-channel maximum, the 8,000 to 192,000 Hz sample rate window, and the 30 million channel-sample budget before any reversal happens.
- Once the samples pass those checks, every channel is reversed independently by the same reverseChannels routine used in the test suite, and then a fresh PCM16 WAV is encoded by the shared encodePcm16Wav function. Negative full-scale samples are clamped to -32768 and positive full-scale samples are clamped to 32767 in signed little-endian PCM bytes.
- Preview the result in the browser, confirm the displayed duration, channel count, sample rate, and file size, and then download the new WAV. The previous download is cleared first so that an old success can never be mistaken for a new result after an error.
Supported Formats, File Size Limits, and Decoded Audio Properties
The Reverse Audio tool accepts the six most common browser-decodable containers, but the codec inside each container depends on your operating system and browser. A familiar extension does not guarantee a successful decode, and the tool reports a specific decode error rather than promising that every MP3, M4A, AAC, Ogg, or WebM file will work. Input acceptance and successful decoding are separate checks, so a file can be accepted by the picker and still fail once BaseAudioContext.decodeAudioData tries to read the bytes.
| Limit | Value |
|---|---|
| Compressed file size | Up to 50 MB |
| Decoded duration | 5 minutes or shorter |
| Channel count | 1 to 8 channels |
| Sample rate | 8,000 to 192,000 Hz |
| Total channel samples | 30,000,000 (frames × channels) |
| Output format | PCM16 WAV, little-endian, freshly encoded |
If any of these limits is exceeded, the file is rejected with a specific message and is not partially processed. The channel-sample budget in particular protects the tab from unexpectedly large decoded arrays even when the compressed source file looks small, because a long, multichannel recording can expand dramatically after Web Audio decoding. The Web Audio AudioBuffer specification describes the underlying data model that drives these checks.
How Local Browser Processing Works and What's in the Output
Every step of the workflow runs in the current tab. The browser validates the MIME type and the 50 MB byte cap, reads the chosen file into an ArrayBuffer, and hands that buffer to BaseAudioContext.decodeAudioData. Decoded audio is rejected rather than truncated if it exceeds the five-minute duration, the eight-channel maximum, the 30 million channel-sample budget, or the 8,000 to 192,000 Hz sample rate range. Once decoding succeeds, the same reverseChannels function exercised by odd, even, and multichannel tests runs on the buffer, and the same encodePcm16Wav function whose RIFF header, PCM clamp values, little-endian bytes, and stereo interleaving are covered by golden assertions writes the result.
The output is a freshly encoded PCM16 WAV, not the original MP3, M4A, AAC, Ogg, WebM, or compressed WAV stream played backward. Original metadata such as album art, ID3 tags, chapters, loop markers, encoder settings, compressed bitrate, and container-specific fields are not copied, because the tool reverses decoded audible sample data rather than editing or preserving the source container. The browser retains the original sample rate and channel count when those values fit the stated limits, so a 44,100 Hz stereo input stays 44,100 Hz stereo in the output, with the left channel reversed independently and the right channel reversed independently and then interleaved again in the correct WAV frame order.
Reversal preserves the decoded duration, sample rate, and channel count, but it moves every audible event to the corresponding position measured backward from the end. The tool does not normalize loudness, remove silence, change pitch intentionally, stretch time, or repair clipping, so any of those adjustments need to happen in a separate audio editor after the download. Because the download is PCM16, the resulting WAV is usually much larger than the compressed source, and reducing floating-point samples to 16-bit can change numerical precision compared to a 24-bit or 32-bit workflow.
Verifying the Reversed WAV and Handling Decode Errors
A reliable workflow starts with the source file, not the output. Listen to the original preview to confirm you reversed the right clip, then create the reversed WAV and listen to the beginning and end of the result to confirm the reversal actually happened. Confirm the duration, channel count, sample rate, and file size displayed by the tool, and open the download in the editor or player where the reversed file will actually be used, because browser preview success does not guarantee that every older device supports the same WAV channel layout or a high sample rate such as 96,000 or 192,000 Hz. The MDN documentation for decodeAudioData lists the exact set of failure reasons a browser can return, which is the same surface area the tool reports back to you.
If the tool returns a decode error even though you picked a file with a supported extension, the most common causes are a non-standard codec inside a familiar container, a corrupted file header, or a sample rate outside the browser's decoder range. Switch to a fresh export from your DAW using a standard codec, confirm the file size is below 50 MB, and retry. If the file passes the size check but still fails to decode, the tool's per-tab Web Audio context was already closed once decoding failed, so reloading the page gives you a clean decoder before you try again. The same Reverse Audio session can also be reused for sound-design experiments, reverse speech, transition effects, sample inspection, and checking the end of a recording from a different perspective, all without uploading a single byte.