Manatee

How to fix a video that plays audio but shows a black screen

· 6 min read

When a video plays sound but shows only black, the player has found and decoded the audio track and failed on the video track. In most cases the video codec is one your player cannot handle (VP9 or AV1 in an MP4, 10-bit HEVC on an older Mac, a Dolby Vision profile the player does not support), and converting to H.264 fixes it. Less often, the video stream is damaged while the audio survived, and that needs a repair. Here is how to tell which you have and what to do about each.

Why audio survives when video does not

Audio and video are separate streams inside one container. They have different codecs, different decoders, and different failure modes. The audio codec in nearly every modern file is AAC, which every player decodes. The video codec varies much more, and its decoder is far more complicated. So when a file is half-supported, it is nearly always the video half that fails.

The same asymmetry applies to damage. Audio frames are numerous and short; video frames are large and depend on each other (a keyframe every few seconds, with the frames between encoded as differences). Corruption that breaks a keyframe takes out everything until the next one, while the audio in that span still decodes.

Step 1: rule out the player and the display

Before touching the file, take thirty seconds to eliminate the boring causes.

  1. Try another player. If a different player shows the picture, the file is fine and your first player lacks the decoder.
  2. Try QuickTime Player specifically if you were using something else, and vice versa. They use different decoders.
  3. If you are on an external display, drag the window to the built-in screen. HDCP and HDR handshake problems occasionally produce a black window on one display and not the other.
  4. Scrub forward a few seconds. Some files start with a stretch of black by design, and some players show black until the first keyframe.

If the picture appears in any of these, you have a compatibility issue, and converting the file is optional rather than required.

Step 2: identify the video codec

If another player opened the file, use its media information panel to read the video codec. The common black-screen culprits:

  • VP9 or VP8. Screen recordings from web-based tools and videos downloaded from the web. Apple’s frameworks do not decode them.
  • AV1. Newer downloads and some phone recordings. Hardware decoding exists only on recent Macs, and software support depends on the macOS version.
  • HEVC 10-bit or HEVC with HDR (HLG, HDR10, Dolby Vision). Standard on recent iPhones. Plays on modern Macs with current macOS, fails on older combinations, and fails in some third-party players even on new hardware. H.264 vs HEVC explains which Macs decode what.
  • MPEG-2. DVDs and older camcorders.
  • Motion JPEG at unusual dimensions, or a proprietary codec from a security camera or drone.

If you have ffmpeg in Terminal, ffprobe video.mp4 lists the streams. If the video stream shows a codec you recognize from this list, go to the conversion step. If it shows a familiar codec like H.264 and still will not display, or if ffprobe reports errors reading the stream, go to the repair step.

Step 3: convert to H.264

A conversion decodes the video (using decoders that cover far more formats than QuickTime’s) and re-encodes it as H.264, which plays everywhere. With Manatee:

  1. Open Manatee and choose Convert. Every feature is available free for 24 hours, with no card or email.
  2. Drop the video in, or right-click it in Finder and choose Fix with Manatee.
  3. Choose MP4 as the target. Pick MOV if you are headed into iMovie or Final Cut Pro.
  4. Open the result, written alongside the untouched original.

Two honest notes. Re-encoding has a quality cost, though at a normal bitrate it is not visible. And HDR video converted to H.264 loses its HDR grading and becomes standard dynamic range; the picture will look flatter than it did on the phone. If you need to keep HDR, you need a player that supports it rather than a conversion.

Step 4: repair, if the stream is damaged

Signs that the video stream itself is broken, rather than merely unsupported:

  • The file shows a picture for the first part and goes black at a fixed point while audio continues.
  • The picture is black in every player, including ones that list the video codec as something ordinary like H.264.
  • The file came from an interrupted recording, a failed copy, or a card that was pulled early.
  • Tools that inspect the file report decode errors, missing references, or invalid data.

In that case, use Manatee’s Repair mode instead of Convert:

  1. Drop the file in with Repair selected.
  2. Wait for the job to finish and read the outcome: Fixed, Partial (with the recovered span stated), or Not fixable.
  3. Open the repaired copy next to the original.

Repair reconstructs the container around the video frames that can still be decoded. Where a damaged region took out a run of frames, those frames are gone, and the repaired file will skip or freeze briefly across that gap while the audio stays continuous. That is the honest best case. Partial recovery explained describes what to expect in more detail, and How to repair a corrupted MP4 covers the full repair process.

Questions

The video is black in QuickTime but the thumbnail in Finder shows a frame. Does that mean it is fine? Finder generates thumbnails with the same frameworks QuickTime uses, so a thumbnail means at least one frame decoded. The file is probably intact and the problem is likely a profile or HDR issue in playback. Try another player, then convert.

My screen recording from a video call shows black. Why? Those tools often record in VP8 or VP9 inside a WebM or MP4 container. Apple’s frameworks decode the Opus or AAC audio and fail on the video. Converting to H.264 MP4 fixes it and is worth doing before you share the recording.

Can a black-screen video be the result of DRM? Yes. Protected content played through a screen recorder is often captured as black by design, and a video purchased with DRM will show black in any player that is not authorized. No conversion or repair changes that.

Will repair or convert fix the colors if the picture is there but looks washed out? Washed-out color is usually HDR content displayed as SDR, not damage. Converting to H.264 fixes it in the sense of making a consistent SDR version. Keeping the HDR look requires an HDR-capable player and display.