A video that plays with no sound in QuickTime on a Mac

A video that plays with a picture and no sound in QuickTime Player usually has an audio track in a format macOS cannot decode, so QuickTime plays the part it understands and says nothing about the rest. Less often the sound is going to the wrong output, or the file never had any audio. Rule out the Mac first, check what the file contains, and if the audio is in an unsupported format, convert the video to MP4 so the sound is re-encoded.

Rule out the Mac in one minute

1. Play something else. Open any other video or song you know has sound. If that is silent too, the problem is the Mac, not the file.
2. Check the output. Open System Settings, Sound, Output and see which device is selected. A monitor with no speakers, an AirPlay speaker in another room and Bluetooth headphones sitting in a bag are the usual culprits. Select the Mac’s own speakers and try again.
3. Check QuickTime’s own volume. Move the pointer over the video and look at the volume slider in the playback controls. It is separate from the Mac’s volume, and it can be all the way down.
4. Check the volume in the menu bar and the mute key while you are there.

If other files play with sound and this one does not, the file is the cause.

Find out what audio the file has

Select the video in Finder, press Command-I, and open More Info. The Codecs line names what macOS recognized in the file, for example H.264 and AAC. Then open the video in QuickTime Player and choose Window, Show Movie Inspector. It lists the video format and, when QuickTime can use the sound, an audio format with its sample rate and channels.

There are three possible results.

• A video codec is listed and no audio codec. Either the file has no audio track, or it has one in a format macOS does not recognize. How to check which codec a video uses on a Mac shows how to tell those apart.
• An audio codec is listed that you do not recognize. Anything other than AAC, MP3, Apple Lossless or plain PCM deserves suspicion. That is the mismatch described in the next section.
• AAC is listed and the video is still silent. QuickTime is playing the track, and the track contains silence. Drop the video into iMovie, which can draw the sound as a waveform under the clip in the timeline. A flat line means silence is what was recorded.

One more thing to try: a file can hold more than one audio track, such as a second language or a commentary, and QuickTime plays the first by default. If the View menu offers Languages, try the other entries.

Why QuickTime plays the picture and drops the sound

A video file is a container holding separate streams: one for the picture, and one or more for the sound. Each stream is compressed with its own codec, and a player needs a decoder for each. QuickTime Player uses the decoders built into macOS. When it has one for the picture and none for the sound, it does not refuse the file. It plays what it can, with no warning that anything is missing.

The audio formats that most often cause this:

• DTS and TrueHD, the surround formats used on discs. Nothing built into macOS plays them.
• AC-3 (Dolby Digital), common in camcorder footage and broadcast recordings. Whether it plays depends on the container and the version of macOS.
• Vorbis and Opus, common in video that began as WebM or MKV and was copied into an MP4 without the sound being re-encoded.
• Telephone-grade formats written by some security cameras, dashcams and voice recorders.

That is also why the same file can have sound on a television or in a phone app and none on the Mac: each device carries its own set of decoders. Container vs codec covers the idea in more depth.

A video that you or someone else exported from an editor, and that lost its sound in the process, is a different problem. The exported video has no sound lists those causes.

Get the sound back by converting to MP4

The fix for an unsupported audio format is to re-encode the sound as AAC, which every Mac, iPhone and browser plays. QuickTime Player cannot do this for you. Its File, Export As command only writes what QuickTime could decode, so the export comes out as silent as the original.

Manatee reads these formats with its own bundled engine instead of relying on the decoders in macOS.

1. Open Manatee and choose Convert.
2. Drop the video onto the window, or drag it onto the menu bar icon.
3. Pick MP4 as the target.
4. Play the new file, which is written beside the original.

Converting to MP4 re-encodes the audio to AAC as part of the job. The original is never modified, nothing is uploaded, and no account is needed. Manatee is free for 24 hours with every feature, then $9 once.

The honest limits: Manatee is not a video editor. It cannot add a soundtrack or boost a quiet one. And if the file has no audio track at all, the converted copy will be just as silent, because there is nothing to convert.

When there was never any sound

Some recordings have no audio track by design, and no tool can add what was not captured.

• Screen recordings. The screen recorder built into macOS (Shift-Command-5) records sound only from a microphone chosen under Options. With None selected, the recording has no audio.
• Time-lapse video from phones and action cameras is recorded without sound.
• Clips saved from messaging apps and websites that began life as animated images often have no audio track.
• Cameras with the microphone switched off in their settings, which includes many security cameras.

For a screen recording, the only fix is to record again with a microphone selected.

When the sound stops partway through

A video whose sound plays for a while and then cuts out, while the picture carries on, points to damage and not to a codec problem. Typically the recording or the copy was interrupted. Manatee’s Repair mode rebuilds what is readable and reports the result as Fixed, Partial or Not fixable. Data that is gone is gone, and it says so. How to check whether a video file is corrupted shows how to confirm the diagnosis first.

Questions

Will converting lower the picture quality? The sound has to be re-encoded, since that is the fix. Whether the picture is touched depends on its codec. Remux versus re-encode explains when a conversion changes quality and when it does not.

The video has sound on my phone. Why not on the Mac? The app on the phone has a decoder for the audio format and macOS does not. The file is fine. Convert a copy for the Mac and keep the original.

Can I fix it by renaming the file to .mp4? No. Renaming changes the label, not the audio inside. The sound has to be re-encoded into a format the Mac can play.

Why does Quick Look have no sound either? Pressing Space in Finder uses the same decoders as QuickTime Player, so a file that is silent in one is silent in the other.