Format & codec problems
Unsupported video format error: what it means and the fix
Short answer
An unsupported-format error rarely means only the file extension. It can mean the container (MP4, MOV, WebM), the codec inside it (H.264, HEVC, VP9) or an audio codec the destination does not take. Read the file with ffprobe, then re-export MP4 with H.264 video and AAC audio, which YouTube recommends and Pinterest and LinkedIn list as supported.
Key takeaways
- The extension tells you the container, not the codec.
- YouTube recommends MP4 with H.264 video and AAC-LC or Opus audio.
- Pinterest accepts MP4 and M4V on the web, plus MOV in its apps, with H.264 or H.265; LinkedIn lists MP4 and several other formats.
- A file that plays on your computer can still use a codec the platform rejects.
Which codec goes in which container
Container and codec are two different things: the container (MP4, MOV, WebM, MKV) is the box, the codec (H.264, HEVC, AAC, Opus) is what is inside. A player or platform can accept the box and reject the contents.
| Container | Video codecs commonly used | Audio codecs commonly used | Source |
|---|---|---|---|
| MP4 | H.264, H.265 (HEVC) | AAC | YouTube recommends MP4 with H.264 and AAC-LC or Opus |
| MOV | H.264, H.265 | AAC, PCM | Pinterest accepts MOV in its apps with H.264 or H.265 |
| WebM | VP8, VP9, AV1 | Vorbis, Opus | The WebM Project: Vorbis or Opus audio |
| MKV | Almost anything | Almost anything | Convert before uploading |
Find your case
| What you see | What it usually means | Do this |
|---|---|---|
| Error appears immediately | Container or video codec not accepted | Re-export as MP4 H.264 (step 2) |
| File plays locally but is rejected | Unusual codec or profile (10-bit, 4:2:2, intermediate) | Convert to 8-bit 4:2:0 (step 3) |
| Video uploads but has no sound | Audio codec rejected | Re-encode audio to AAC (step 2) |
| Screen recording or rip rejected | Variable frame rate or odd container | Re-export with a constant frame rate |
Fix it step by step
Read the file
ffprobe -hide_banner in.mkvlists the container, video codec, pixel format, audio codec and frame rate. Note them before changing anything.Export a standard MP4
ffmpeg -i in.mkv -c:v libx264 -pix_fmt yuv420p -c:a aac -b:a 160k -movflags +faststart out.mp4.Drop to 8-bit 4:2:0
-pix_fmt yuv420p makes the picture 8-bit 4:2:0, which every platform decodes; 10-bit and 4:2:2 files from cameras and pro editors often are not accepted.
Check the platform's own list
Compare with the platform's help page: Pinterest lists MP4 and M4V for web uploads and MP4, MOV and M4V in its apps, with H.264 or H.265; LinkedIn lists MP4 and others; YouTube recommends MP4.
Keep quality when converting
- Use CRF 18 to 23 with x264 for a quality-first export.
- Keep the original resolution and frame rate.
- Do not convert from an already compressed copy if you still have the original.
Check your file
Extension and MIME type are labels, not proof of the container. Dimensions and duration come from this browser's media reader. This does not detect codecs, bitrate, corruption or platform upload compatibility. Files and measurements are not sent anywhere.
Frequently asked questions
What does unsupported format mean?
The container, video codec or audio codec is not one the destination accepts. The extension alone cannot tell you which.
What is the most accepted video format?
MP4 with H.264 video and AAC audio.
How do I check what codec my video uses?
Run ffprobe on the file, or use a file checker, and read the codec on the Stream lines.
Sources
- YouTube Help: Recommended upload encoding settings (official, checked 2026-10-06)
- Pinterest Help: Review Pin specs (Video Pin file types and encoding) (official, checked 2026-10-06)
- LinkedIn Help: Video sharing troubleshooting (formats and limits) (official, checked 2026-10-06)
- FFmpeg Documentation: Automatic stream selection and -map (official, checked 2026-10-06)
Reviewed 2026-10-06. Steps not attributed to a source are general video practice or computed above.