Video Codec Checker
Find out why a video does not play – or make sure it will before you send it. The codec checker reads the container, the video codec with its profile and pixel format, the audio codec, frame rate, resolution and bitrate, and rates how widely each part is supported in browsers, on phones, on TVs and in editing software. It explains what to change if something is not widely supported.
- Files stay on your device
- No sign-up
- Free to use
Codec check
Reads the container, video and audio codecs, profile, pixel format and bitrate, then tells you where the file plays. The file is read in place; it is not converted or uploaded.
Reading the codec information takes a moment the first time, because the media engine (about 32 MB) is loaded once.
How to use Video Codec Checker
- Drop a video onto the page.
- Click “Check codecs”.
- Read the support rating for video and audio.
- Convert with Video to MP4 if needed.
Video Codec Checker features
Video codec and profile
H.264, HEVC, VP9, AV1, ProRes and more.
Audio codec
AAC, MP3, Opus, AC-3, DTS …
Pixel format
Spots 10-bit and 4:2:2 files that phones reject.
Support rating
Clear verdict with explanations.
No conversion
The file is read in place.
Private
Processed on your device; the video is never uploaded.
When to use Video Codec Checker
- Finding out why a video shows only sound or a black screen.
- Checking exports before uploading to a website.
- Verifying files from cameras, drones and screen recorders.
- Preparing videos for TVs and media players.
Video Codec Checker FAQ
What is the difference between container and codec?
The container (MP4, MKV, MOV) is the file format that holds the streams; the codec (H.264, HEVC, AAC) is how the picture and sound are compressed. A player must support both.
Which combination plays everywhere?
MP4 with H.264 video (8-bit, 4:2:0) and AAC audio. Almost every browser, phone, TV and editor plays it.
Why does my iPhone video not play on Windows?
iPhones record HEVC by default. Windows needs an extra codec, and Firefox does not play HEVC. Convert to H.264 or change the camera format to “Most compatible”.
What does 10-bit mean?
More colour precision, used for HDR. Many browsers and older devices only decode 8-bit H.264.
Why does the first run take longer?
The media engine, FFmpeg compiled to WebAssembly (about 32 MB), is downloaded once and then cached by your browser.
Is my video uploaded?
No. FFmpeg runs as WebAssembly in your browser, so the video stays on your device.
Why some videos do not play
A video file is a container holding several streams – usually one video and one or more audio streams, sometimes subtitles. Each stream is compressed with a codec, and a player must understand both the container and every codec to play the file. When one part is missing, the result is a black screen, sound without picture or an error message.
H.264 with AAC audio in an MP4 container is the most widely supported combination by far. Newer codecs like HEVC, VP9 and AV1 compress better, but support depends on browser, operating system and hardware: HEVC plays in Safari and on most phones but not in Firefox, AV1 needs recent hardware. Professional formats like ProRes and DNxHD are made for editing and are not played by browsers at all.
Details within a codec matter as well. H.264 has profiles; High 10 and 4:2:2 profiles used by some cameras are not decoded by browsers. The pixel format tells you whether the video uses standard 8-bit 4:2:0 colour or something more demanding.
The checker reads all this information with FFmpeg without converting the file, so even large videos are analysed in seconds after the engine is loaded. If the verdict is not “widely supported”, the Video to MP4 converter creates a compatible copy.
The file is read on your device only.