WMV to AU Converter

How to Convert WMV to AU Online

1. Upload Your WMV File: Drag and drop, or click "+ Add Files" to select one or more Windows Media Video files from your device. Batch conversion is supported — queue multiple WMV clips and apply the same AU settings to all of them.
2. Pick Audio Codec and Quality Preset: Default is PCM µ-law (8-bit, G.711 telephony) so the output plays out of the box on Sun/NeXT systems, Java sun.audio callers, and /dev/audio on classic Unix. Pick PCM A-law for European telephony interop, PCM signed 16-bit big-endian (S16BE) for full-fidelity uncompressed AU, or PCM S16LE / S24LE / S32LE for higher dynamic range. Quality Preset ranges Lowest to Highest; for bit-rate control, switch between Constant Bitrate (CBR), Variable Bitrate (VBR), or a custom bps value.
3. Set Audio Channel, Sample Rate, and Trim (Optional): Audio Channel defaults to ORIGINAL — switch to Mono to halve file size for voice work, or keep Stereo for music. Audio Sample Rate accepts 8000 Hz (telephony standard for µ-law/A-law), 11025, 16000, 22050, 24000, 44100 (CD quality), or 48000 Hz. Use Trim to extract a specific in/out range with hh:mm:ss.ms precision instead of converting the full clip.
4. Convert and Download: Click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Why Convert WMV to AU?

WMV (Windows Media Video) is a Microsoft container/codec family introduced in 1999 whose audio track is almost always Windows Media Audio (WMA). AU is Sun Microsystems' minimal audio format — magic number 0x2e736e64 (".snd") — and was the de facto sound format on Unix workstations, NeXT machines, and the early web. Converting WMV → AU strips the video track, decodes WMA, and re-encodes the audio into a header-light file that legacy Unix toolchains, telephony pipelines, and Java audio classes can read directly.

• Java sun.audio and javax.sound.sampled ingestion — AU is one of the small set of formats Java's built-in audio APIs decode without third-party libraries. Useful when you're embedding clips into a legacy Java applet, Swing app, or AudioInputStream consumer.
• Telephony / IVR audio (G.711) — µ-law and A-law at 8 kHz mono 8-bit produce ~64 kbit/s "toll quality" speech, the ITU-T G.711 standard since 1972. Asterisk, FreeSWITCH, and legacy PBX systems consume AU/G.711 natively.
• Unix /dev/audio and SPARC archives — Classic Solaris and SunOS workstations exposed /dev/audio accepting µ-law AU streams. Archivists pulling audio off old SPARCstation, NeXTcube, or HP-UX disks often need WMV recordings down-converted to match.
• Lightweight programmatic parsing — AU's 24-byte fixed core header (six 32-bit big-endian words) is trivial to read, write, and stream without external libraries — handy for embedded systems, test fixtures, and audio-tool unit tests.
• Preserving the audio of legacy WMV archives — Old training videos, voicemail backups, lecture recordings, and webcam captures saved as WMV often need only the audio. Extracting to AU keeps the file portable to systems where WMV/WMA codecs are no longer installed (Telestream's Flip4Mac for macOS ended sales July 2019).
• Scientific / academic audio sets — Several university speech corpora distribute clips as .au because the format predates WAV in Unix tradition; matching their format simplifies dataset ingestion.

WMV vs AU — Format Comparison

AU Encoding Quick Guide

Frequently Asked Questions

Why would I pick AU over WAV or MP3 in 2026?

You wouldn't, unless something on the receiving end specifically asks for it. The realistic reasons today are: feeding a legacy Java application that uses javax.sound.sampled without a codec dependency, sending audio into a telephony / IVR system that expects G.711 µ-law or A-law at 8 kHz, restoring archives from old Sun/NeXT/SPARC disks, or processing a research speech corpus distributed as .au. For general listening, WMV to MP3 or WMV to WAV is the better choice.

What's the difference between PCM µ-law and PCM A-law in AU output?

Both are 8-bit logarithmic companding schemes defined by ITU-T G.711, both produce roughly 64 kbit/s at 8 kHz mono, both are "toll-quality" speech. The difference is the compression curve: µ-law (mu-law) is used in North American and Japanese phone networks, A-law is used in European and most other countries' networks. If you're feeding a US-based Asterisk box, pick µ-law; if you're targeting European telephony, pick A-law. For non-telephony use, the two sound nearly identical.

Will the converter lose video — and is that expected?

Yes. AU is an audio-only format, so the video track of your WMV is discarded entirely. Only the audio stream (typically WMA) is decoded and re-encoded into AU. If you want to keep the video, convert to a video target instead, e.g. WMV to MP4. For other audio targets from WMV, see the general audio converter.

Can I trim a section of the WMV before converting?

Yes — the Trim control on the Advanced Options panel lets you set a start time and duration in hours:minutes:seconds.milliseconds before the audio is written to AU. Only the trimmed range is encoded, which is faster than converting the whole file and trimming after. For more elaborate cuts on already-converted AU files, use the audio cutter.

What sample rate should I pick if I'm targeting telephony?

8000 Hz mono with µ-law or A-law encoding — that's the G.711 telephony standard since 1972 and what Asterisk, FreeSWITCH, and most PBX/IVR systems expect. Don't upsample above 8 kHz for µ-law/A-law: it inflates the file without improving the telephony pipeline, which will downsample back to 8 kHz anyway. For non-telephony AU output, 44100 Hz is the safe general default.

Why is my AU file bigger than I expected?

AU has no built-in psychoacoustic compression — it's PCM, possibly companded to 8 bits with µ-law/A-law but never MP3-style lossy. A stereo 16-bit AU at 44.1 kHz is about 10 MB per minute. If size matters and lossy is acceptable, convert the WMV audio to MP3, AAC, or Opus instead. If you must stay in AU, drop to mono and use µ-law at 8 kHz — that yields about 480 KB per minute.

Does Audacity / ffmpeg / SoX still open AU files?

Yes. Audacity, ffmpeg, SoX, VLC, and most professional DAWs all read the AU format including µ-law, A-law, and linear PCM variants. The format hasn't changed substantially since the 1990s, so even very old tooling stays compatible. Note: some Windows-only consumer players don't recognise .au — open in Audacity or VLC if double-clicking fails on Windows.

How big can my WMV upload be?

Files are uploaded over an encrypted connection and processed on xconvert's servers, so the practical ceiling is upload size and connection speed. There's no sign-up, no per-file daily cap, and no watermark. Very long lecture recordings (multi-hour WMVs) may run faster if you split the file or use the Trim option to extract just the segment you need.

Is the original WMV file uploaded to a server?

processing happens on our servers — your file isn't stored long-term on our servers, there's no account requirement, and nothing is shared with third parties. When the session ends, the working file is released. This makes WMV → AU safe for sensitive recordings such as legal depositions, internal training, or medical dictation.