A video with no sound and no error message is more confusing than one that refuses to open. Most players, when they hit an audio format they can't decode, don't warn you - they just play the picture in silence. So before assuming the file is broken, spend two minutes finding out what the audio actually is. In most cases it's one of a handful of formats that certain players skip, and the fix is to convert the audio alone, leaving the picture untouched.
#First, rule out the boring causes
- Volume and mute. Check the system volume and the player's own volume slider - some players remember being muted.
- The output device. On Windows, click the speaker icon in the taskbar and check where sound is going. Bluetooth headphones sitting in another room are a classic.
- Other files. If no video or music on the device makes a sound, the problem is your audio setup, not the file.
- VLC. Open the file in VLC (free). If you hear sound there, your usual player can't decode the audio format - read on. If VLC is silent too, jump to When the file really has no sound.
#Check what the audio is
In VLC, open Tools → Codec Information (on a Mac, Window → Media Information) and look at the stream marked Audio. The free MediaInfo app shows it under "Audio", and Wave's inspect screen lists it as soon as you drop the file, without uploading anything. Then match it against this table:
Audio formats that play silently, and where
| Audio says | What it is | Often silent in |
|---|---|---|
| AC-3 · A52 · Dolby Digital | The sound format of DVDs, Blu-rays and TV broadcasts | Chrome, Firefox, web-based players and upload previews |
| E-AC-3 · EC-3 · DD+ · "DDP" in the filename | Dolby Digital Plus, used by streaming services and many downloaded films and episodes | Chrome, Firefox, web-based players |
| PCM · LPCM · twos · sowt | Uncompressed audio from cameras, screen recorders and editing apps | Some browsers, phones and upload sites |
| Opus | Modern format used by browsers, Discord and WhatsApp | Apple's players when it's inside an MP4 |
| DTS · TrueHD | Blu-ray surround formats, usually in MKV files | Web browsers and many TVs |
| AAC · mp4a | The standard MP4 audio format | Plays almost everywhere |
#Why Dolby audio is the most common culprit
AC-3 (Dolby Digital) has been the sound format of DVDs and broadcast TV since the 1990s, and its successor E-AC-3 (Dolby Digital Plus) is what most streaming services use for surround sound. If a film or episode came from a disc, a TV recording or the wider internet, there's a good chance its audio is one of the two. "DDP5.1" in a filename means Dolby Digital Plus in 5.1 surround.
Both are perfectly legal inside an MP4, and VLC, most TVs and home-cinema gear play them. But they're licensed from Dolby, and Google Chrome and Mozilla Firefox don't include decoders. So the same MP4 plays with full sound on your TV and in silence in a browser tab, a web-based video player, or an app built on browser technology. It's also why Wave converts AC-3 and E-AC-3 to AAC whenever it writes an MP4: a file that plays silently in the browser you made it in isn't much use.
#The fix: convert the audio, keep the video
For almost every silent MP4, the picture doesn't need touching. When you drop a file onto Wave, it checks both streams. If the video is already in an MP4-friendly format (H.264, HEVC or AV1) and only the audio is the problem, Wave copies the video exactly as it is and converts just the audio to AAC:
- Stereo audio becomes 192 kbps AAC, which sounds the same as the original on normal speakers and headphones.
- 5.1 surround stays 5.1, as AAC at a higher bitrate, so a home-cinema setup still gets surround sound.
- Extra audio tracks - a second language, a director's commentary - are kept and converted too.
- The picture isn't re-encoded, so it loses nothing, and the job is much quicker than a full conversion. A short clip takes seconds; a full-length film takes longer, because its whole soundtrack still has to be re-encoded in your browser.
Everything runs on your device, and the file is never uploaded. For an MKV with the same problem, MKV to MP4 does the same thing while changing the file type. If you prefer the command line, ffmpeg does the same job with ffmpeg -i input.mp4 -c:v copy -c:a aac -b:a 192k output.mp4.
#If it's silent only in your video editor
Editing apps are pickier about audio than players. Two cases come up again and again:
- DaVinci Resolve on Linux can't decode AAC - the most common audio format in MP4 - for licensing reasons, so phone and camera clips import silent. There, convert the audio to uncompressed PCM instead:
ffmpeg -i input.mp4 -c:v copy -c:a pcm_s16le output.mov. On Windows and Mac, Resolve plays AAC normally. - Variable frame rate footage from phones and screen recorders can make audio drift or drop out in editors. That's a timing problem rather than a format one; HandBrake's "Constant Framerate" option fixes it.
#When the file really has no sound
If VLC is silent too and the codec information shows AAC (or no audio stream at all), the sound genuinely isn't there:
- No audio track. Some screen recorders only capture sound if you switch it on, and some apps block audio capture entirely. Wave's inspect screen tells you when a file has no audio stream - there's nothing to convert.
- A silent or wrong track. Files with several audio tracks sometimes default to an empty or commentary track. In VLC, try Audio → Audio Track and pick another one.
- A damaged file. An interrupted copy or download can lose the end of the audio. Copy or download it again.
#The short version
- Rule out volume, mute and the output device, then test in VLC.
- Check the audio format: AC-3, E-AC-3, PCM, Opus, DTS and TrueHD are the usual silent ones.
- Convert only the audio to AAC. The video is copied untouched, and Wave does it in your browser.
- Silent in VLC too: no audio track, the wrong track, or a damaged copy.