HEVC to AU Converter

Convert HEVC to AU: Read This First

A bare .hevc file is a raw H.265 video bitstream — by the standard's own design it carries picture only, with no audio track inside it. So if your goal is to pull a soundtrack out of a .hevc and save it as an AU (.au, the classic Sun/NeXT "snd" audio format), there is usually nothing to pull: the result comes out silent or empty. This page is honest about why that happens, shows exactly how the converter behaves, and points you to the file that actually holds your audio.

How to Convert HEVC to AU

1. Upload Your HEVC File: Drag and drop your .hevc onto the page, or click "+ Add Files" to choose it from your computer. You can queue several files and process them in one batch with the same settings.
2. Set Audio Channel and Audio Sample Rate: Open "Show All Options" to set Audio Channel (Original, Mono, or Stereo) and Audio Sample Rate (Original, or a fixed rate). AU output is written with μ-law, the classic Sun encoding for .au, and there is no codec picker on this page — so these two controls are what actually shape the file. Leave both on "Original" to mirror the source.
3. Trim (Optional): Switch the Trim control from "Unchanged" to set a start time and duration if you only want part of the timeline rather than the whole stream.
4. Convert and Download: Click "Convert" and download your AU file. No sign-up, no watermark. If you uploaded a true raw stream, the audio will be empty — that is the format, not a fault.

Walk-through: Why a Raw HEVC File Has No Audio to Extract

HEVC (High Efficiency Video Coding, also called H.265) was approved as an ITU-T standard on April 13, 2013 and standardized jointly as ISO/IEC MPEG-H Part 2. It is a video-only compression standard — it defines how picture frames are encoded, achieving roughly 50% lower bitrate than H.264/AVC at comparable quality, and says nothing about audio. The key word for a .hevc, .h265, or .265 file is elementary: an elementary stream holds a single media type on its own, so a spec-correct .hevc contains only compressed video frames and parameter sets — no audio, no timing layer, no container.

In a normal recording or download, the H.265 video is muxed into a container alongside a separate audio track. Whether your conversion produces any sound depends entirely on what is genuinely inside the file you uploaded:

• A genuine, spec-correct .hevc stream holds no audio at all. The decoder finds nothing to extract, so the AU comes out silent or the job returns no usable output. No setting on this page can create a soundtrack that was never written into the file.
• A file named .hevc that actually plays with sound is unusual, but if yours does, it is almost certainly a container (an .mp4 or .mov) that was renamed or relabeled with a .hevc extension. If a real audio track is inside, the converter decodes it and writes PCM-in-AU normally.
• Quick test: open the file in VLC. If you hear audio, it has a track to extract; if it plays as silent video, it does not, and the AU will be empty.

What AU Is, and Why It Is a Niche Target

AU is one of the oldest audio formats still in circulation. It was created by Sun Microsystems, was native to the SPARCstation 1 hardware (SunOS exposed it through the /dev/audio device), and became common on NeXT systems and early 1990s web pages — it is also the format Java's original sun.audio / AudioClip API played. The file begins with the four-byte magic number .snd (0x2e736e64), and every field in that header is stored big-endian, matching AU's Motorola/SPARC heritage. The format can hold μ-law, A-law, and linear PCM at 8, 16, 24, or 32-bit. This converter writes μ-law — the encoding .au was born with on Sun workstations, and the one most AU readers handle without complaint.

AU Format at a Glance

Even when you do have real audio to extract, AU is a legacy choice. It is well supported in older Unix/Java tooling and in editors like Audacity, but it is not a modern delivery format — for everyday playback or sharing, MP3 or WAV is the safer target. Reach for AU specifically when a legacy Unix workflow, a Java applet, or a Solaris-era pipeline expects a .au/.snd file.

Does Your .hevc File Actually Have Audio?

Not every file with a .hevc extension is a bare elementary stream — and the answer decides whether this conversion produces anything. Where the file came from tells you almost everything:

The middle row is the case people miss. Because .hevc names a codec rather than a container, an .hevc file produced here is muxed into Matroska so it stays playable — which means it carries the audio track from whatever you converted, and extracting that audio to AU works exactly as you would expect. It is the genuine Annex B streams from the first row that have nothing to give.

Common Errors and How to Fix Them

• "My AU file is silent or zero-length" — The .hevc is a true H.265 video elementary stream, so there is no audio to decode. You need the original container the video came from — convert that file to AU instead.
• "The conversion failed or returned no output" — Same root cause: an audio-only target needs an audio stream in the input. Confirm the file plays with sound in a media player before converting.
• "It worked, but I actually wanted the video" — AU is an audio-only format, so the picture is discarded by design. To keep the footage in a playable file, use HEVC to MP4 instead.
• "My .au won't open in a modern player" — Some current apps no longer ship AU support because it is a legacy format. Audacity, VLC, and FFmpeg open it; for broad compatibility, convert your source to MP3 or WAV instead.
• "A long source uploads slowly" — A long 4K H.265 capture can be large, and the real wait is upload time over your connection, not anything on your device. Trim to the segment you need before uploading.

When This Doesn't Work

If your file is a real video-only .hevc, no online tool can conjure audio that was never written into it — the data simply isn't there. Your genuine path is to start from the original container that holds both the H.265 video and a separate audio track: convert it with MP4 to AU for MP4 files, MKV to AU for Matroska files, or MOV to AU for QuickTime files. Those formats interleave video and audio, so there is a real track to extract. If you would rather have a more widely playable result than legacy AU, MP4 to MP3 is the everyday choice. Note that many "HEVC to AU" tools online accept the upload and run the job without warning you that a bare H.265 stream has no soundtrack — the empty result is the format talking, not the converter.

Frequently Asked Questions

Why is my HEVC to AU output silent or empty?

Because a raw .hevc file is an H.265 video elementary stream and holds no audio. A spec-correct .hevc, .h265, or .265 contains only compressed video frames and parameter sets — there is no audio track inside it to decode, so any AU produced from a bare stream will be silent or empty. The audio for that footage lived in the container (an .mp4, .mkv, or .mov) that the video was demuxed from. Convert that original container to AU instead.

Does a .hevc file contain audio I can extract to AU?

Normally no. HEVC, defined by ITU-T H.265 and ISO/IEC MPEG-H Part 2 and approved in 2013, is a video-only codec, and a plain .hevc file is a raw video bitstream with no audio track. An elementary stream carries only one kind of data. You only get sound out if the file you uploaded is actually a container — for example an MP4 misnamed .hevc — that happens to carry an audio track alongside the video.

My video clearly has sound — which tool do I actually use?

Start from the original container, not a bare stream. If your file is an MP4, use MP4 to AU; if it is a Matroska file, use MKV to AU; if it is a QuickTime file, use MOV to AU. All three interleave video and audio together, so the converter has a real track to decode. A bare .hevc stream does not. If legacy AU is not a hard requirement, MP4 to MP3 gives you a more universally playable file.

What is the AU format, and what encoding does this converter use?

AU is the classic Sun Microsystems audio format (often called "snd" after its .snd magic number), common on NeXT systems, early web pages, and Java's original audio API. It can hold μ-law, A-law, or linear PCM at 8 to 32-bit. This converter writes μ-law, the encoding .au files were born with on Sun workstations and the one legacy AU readers handle most reliably. μ-law stores one byte per sample and compands the signal logarithmically, so it packs a wide dynamic range into 8 bits rather than storing samples verbatim — expect roughly 5 MB per minute at 44.1 kHz stereo, or about half a megabyte per minute at the classic 8 kHz mono telephone setting. There is no codec dropdown on this page; Audio Channel and Audio Sample Rate are what shape the output.

How can I tell whether my .hevc actually contains audio before converting?

Play it in a media player such as VLC. If you hear sound, the file is almost certainly a container that was renamed with a .hevc extension, and it will convert to AU normally. If it plays as silent video, it is a true video-only H.265 stream and there is nothing to extract. In our testing, files that played silently in VLC produced empty AU output every time regardless of the channel or sample-rate settings, while renamed containers that played with sound converted cleanly.

Does a .hevc file downloaded from xconvert have audio to extract?

Usually yes, which is the exception to everything above. .hevc names a codec rather than a container, so when you convert something to .hevc here the result is muxed into Matroska and given the .hevc extension — it is an MKV in all but name, carrying the H.265 video alongside whatever audio track your source had. Feed one of those back into this tool and the audio extracts to AU normally. The files that come out silent are the genuine Annex B elementary streams that encoders and demuxers produce, which contain video frames and parameter sets and nothing else.

Why does my AU file sound muffled or telephone-like?

Two things stack up here. μ-law itself is an 8-bit companded encoding, so it is not bit-exact with the source — that is what .au has always been, not a fault. The bigger factor is the sample rate: if Audio Sample Rate is left on "Original" the output follows whatever the source had, but forcing 8000 Hz band-limits the audio to roughly telephone bandwidth, which is exactly the sound Sun's /dev/audio was designed around. For full-range audio, set 44100 or 48000 Hz instead. If neither the encoding nor the file extension is a hard requirement, extracting to MP3 or WAV from the original container will sound better.

How are my files handled, and how long are they kept?

Your file is uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — no sign-up, no watermark, and never shared or made public. The realistic limit on a very large 4K HEVC capture is upload time over your connection, not anything on your device.