Why won’t my video play?

A practical checklist for codec, container, browser, app, and device compatibility problems.

Check the file extension

MP4, MKV, MOV, and WebM are containers. The extension does not tell the full story. The video and audio streams inside may use codecs your device cannot decode.

Try a safer format

For broad compatibility, convert a copy to MP4 with H.264 video and AAC audio.

Common causes

• The TV supports MP4 but not the video codec inside.
• The browser supports the video but not the audio track.
• The file uses a high bit depth, profile, or level the device cannot handle.
• The file is damaged or incomplete.