SWF to AU Converter

SWF to AU Converter

This tool extracts the audio stream embedded in a Flash SWF file and re-encodes it as a Sun/NeXT .au audio file. It is an audio-extraction job, not a video conversion: any embedded sound is pulled out and the animation, vector art, and ActionScript are discarded. Two things are worth knowing before you start. First, many SWF files hold little or no continuous audio — a button-click sound or a short jingle, sometimes nothing at all — so there may be nothing meaningful to extract. Second, AU is a legacy Unix audio format; if you simply want portable audio that plays everywhere, SWF to MP3 is almost always the better choice, and if you actually want the animation itself, SWF to MP4 keeps the visuals.

SWF Format at a Glance

AU Format at a Glance

How to Convert SWF to AU

1. Upload Your SWF File: Drag and drop your .swf file onto the page or click "Add Files" to select it. You can queue several SWF files and process them with the same settings.
2. Set Audio Sample Rate: Leave Audio Sample Rate on "ORIGINAL" to keep the SWF's embedded rate, or pick a value (for example 8000 Hz, the classic μ-law rate) if you need a specific AU profile.
3. Adjust Audio Channel and Trim: Use Audio Channel to force mono or stereo, and use Trim to keep only a portion of the audio if the SWF has long silent gaps. The defaults are tuned to preserve the original audio.
4. Convert and Download: Click "Convert" and download your .au file. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours. No sign-up, no watermark.

Frequently Asked Questions

Will this work even though Flash Player is dead?

Yes. The converter reads the SWF binary directly on our servers and pulls the embedded audio stream out of it — it does not run Flash Player or load the animation. Adobe ended Flash Player support on December 31, 2020, but the SWF file itself is just a container, and its audio data can still be decoded and re-encoded long after the runtime was retired.

What if my SWF has no audio to extract?

Then there is nothing for the tool to convert. Plenty of SWF files are pure vector animation, a game UI, or an ad with only short click sounds — and some have no sound track at all. If the conversion returns an empty or near-silent result, the SWF most likely never contained a continuous audio stream in the first place.

Should I use AU at all, or convert to something else?

For almost any modern use, no. AU is a legacy Sun/NeXT format from the 1980s and is poorly supported by today's players and phones. Choose AU only if a specific old Unix toolchain, NeXT app, or archival workflow requires .au. Otherwise use SWF to MP3 for portable, universally playable audio, or SWF to WAV for uncompressed audio you plan to edit.

What encoding does the output AU file use?

AU files carry a short header (the .snd magic, 0x2e736e64) followed by the audio payload. This converter writes 8-bit G.711 μ-law by default; A-law and 16-bit big-endian linear PCM (PCM_S16BE) can be selected in the advanced options. The classic, smallest AU profile is 8-bit μ-law at an 8000 Hz sample rate, which is why you may want to set Audio Sample Rate to 8000 Hz for maximum compatibility with old μ-law tools.

Will I lose audio quality going from SWF to AU?

It depends on what is inside the SWF. SWF audio is often already lossy — MP3, Nellymoser, or Speex — so decoding it and re-encoding to AU does not recover anything that was already discarded. The default AU output is 8-bit μ-law, a telephony-grade companding that packs roughly 14 bits of dynamic range into 8, so expect a slight further fidelity cut on music; for a full-fidelity copy of the decoded audio, select 16-bit PCM (PCM_S16BE) in the advanced options. Downsampling to 8000 Hz on top of that narrows the sound further still.

I really wanted the animation, not just the sound — what do I use?

Most people who land on an SWF audio page actually want the Flash content itself, not a stripped audio track. To keep the visuals, use SWF to MP4, which renders the animation timeline to a standard video file that plays on any device. The AU output here keeps only the sound.

Does the tool play the Flash animation to capture its audio?

No. The converter decodes the audio stream directly from the SWF binary on our servers — it never launches Flash Player or renders the animation timeline. That is why extraction still works even though the Flash runtime was retired: the sound data is stored inside the file and can be decoded independently of the dead player.

What sample rate does Flash audio use, and what should I set?

Flash embeds audio at 5512, 11025, 22050, or 44100 Hz (Speex streams run at 16 kHz and Nellymoser at 8 or 16 kHz). Leave Audio Sample Rate on "Original" to keep whatever the SWF stored; drop it to 8000 Hz only when you specifically want the classic μ-law telephony AU profile, which trades bandwidth for maximum compatibility with old Unix tools.

Can I pull just a few seconds of audio out of a long SWF?

Yes. Set a start time and duration with the Trim control and only that segment is decoded and written to the .au file. This is handy when a SWF holds one short jingle or click sound surrounded by long silent stretches — you extract the part that matters instead of a mostly-empty track.