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Open a file to see its video and audio codecs, profile, level, bit depth and codec tag, each explained in plain English. It all happens on your device.
To find out what codec a video uses, open it here and look at the codec card in the Video section: it names the compression format (H.264, HEVC, AV1, VP9, ProRes and so on) along with its profile, level, bit depth, chroma subsampling and the codec tag stored in the file. The Audio section does the same for the soundtrack, which matters because a clip can fail to play because of its sound alone.
The file extension won’t tell you this. .mp4, .mov and .mkv are containers: boxes that hold a video stream, one or more audio streams and sometimes subtitles. Two MP4 files can carry completely different codecs, which is why one plays on an old laptop and the other shows an error. If you are here because of a playback error, the video codec not supported guide walks through the fixes.
The file is read in your browser by three readers (a built-in MP4/MOV box reader, Mediabunny and MediaInfo compiled to WebAssembly) and is never uploaded. Because nothing is decoded to read these details, the checker works even when your browser can’t play the video.
Drop the file on Drop a video or photo here or press Open a file (Ctrl/Cmd+O). To see how the page works first, press Try the sample video.
The page opens on the Video section. The codec card shows the codec, profile, level, bit depth, chroma subsampling and codec tag (such as avc1, hvc1 or hev1). The ⓘ beside each value explains it.
The Plays on row under the codec card gives a quick read on compatibility, so you can see whether the format is likely to cause trouble on the device you have in mind.
Press J or K, or pick Audio in the section list, to see the audio codec, channels, sample rate and bitrate. Press / to search every field at once, for example for “codec”.
Open Report and press Copy or Download text to paste the full technical report into a support ticket, forum post or delivery checklist.
Every video file has two layers. The container is the file format you see in the name: MP4, MOV, MKV, WebM, AVI. It organises the data, stores the timing and holds the tags. The codec is the method used to compress the pictures and the sound inside it. A player needs to understand both, and the codec is the part that most often goes wrong.
| Container | Video codecs you will usually find | Audio codecs you will usually find |
|---|---|---|
| MP4 / M4V | H.264, HEVC, AV1 | AAC, sometimes AC-3 or E-AC-3 |
| MOV (Apple QuickTime) | H.264, HEVC, Apple ProRes | AAC, PCM, ALAC |
| MKV (Matroska) | Anything: H.264, HEVC, AV1, VP9, older formats | AAC, AC-3, E-AC-3, DTS, FLAC, Opus |
| WebM | VP8, VP9, AV1 | Opus, Vorbis |
| AVI | Older formats such as MPEG-4 Part 2 (DivX, Xvid), Motion JPEG | MP3, AC-3, PCM |
| MTS / M2TS (camcorders, Blu-ray) | H.264, MPEG-2, HEVC | AC-3, LPCM |
The video file info report lists every stream in the container, including timecode and telemetry tracks, if you need more than the codec.
| Field | Example | What it tells you |
|---|---|---|
| Codec | HEVC (H.265) | The compression standard. H.264 is also called AVC; HEVC is also called H.265. |
| Profile | Main 10, High | Which set of tools the encoder was allowed to use. Main 10 means 10-bit HEVC; High is the usual H.264 profile for HD. |
| Level | 5.1 | A ceiling on resolution, frame rate and bitrate. Hardware decoders advertise the highest level they can handle. |
| Bit depth | 8-bit, 10-bit | How many shades each colour channel can take: 256 at 8-bit, 1,024 at 10-bit. HDR needs 10-bit. |
| Chroma | 4:2:0, 4:2:2 | How much colour detail is stored compared with brightness detail. |
| Codec tag | avc1, hvc1, hev1, av01, apch | The four-character code in the file that tells players which decoder to use. |
Our eyes notice fine changes in brightness more than fine changes in colour, so most video stores colour at lower resolution. 4:2:0, used by phones, streaming services and YouTube uploads, keeps one colour sample for every block of four pixels. 4:2:2, common in professional cameras and ProRes, keeps twice as much, which helps with green-screen keying and heavy grading. 4:4:4 keeps full colour and is mostly used for screen recordings and graphics.
Both tags mean HEVC. With hvc1, the decoder setup information (the parameter sets) sits in the file’s header; with hev1, it may instead be repeated inside the video stream. Apple’s players, including QuickTime, Photos and Safari, expect hvc1, so an hev1 file that plays fine in VLC or Chrome can refuse to open on an iPhone or Mac. Re-wrapping the stream with the hvc1 tag usually fixes it without re-encoding, for example with ffmpeg:
ffmpeg -i input.mp4 -c copy -tag:v hvc1 output.mp4
metadata.video shows the codec tag but does not change it. The command above copies the streams as they are and only rewrites the container.
A codec (short for coder–decoder) is the agreed method for squeezing video into a manageable size and unpacking it again for playback. Uncompressed 1080p at 30 frames per second needs about 750 megabits per second even in the leanest 8-bit 4:2:0 form; a phone records the same scene at a few tens of megabits. Codecs get there by storing complete pictures only now and then and describing the frames in between as changes, by throwing away detail the eye is unlikely to miss, and by packing what remains very efficiently.
| Codec | Also called | Where you meet it | Strength | Watch out for |
|---|---|---|---|---|
| H.264 | AVC, MPEG-4 Part 10 | Almost everywhere: older phones, web video, Blu-ray, video calls | Plays on practically every device | Larger files than newer codecs at the same quality |
| HEVC | H.265 | iPhone “High Efficiency” recordings, 4K and HDR video, many cameras | About half the size of H.264 in the best cases; supports HDR | Needs an extension on some Windows PCs; browser support depends on hardware |
| AV1 | AOMedia Video 1 | Streaming services, newer screen recorders, some phones | Very efficient and royalty-free | Older phones and PCs lack hardware decoding |
| VP9 | YouTube streams, WebM files | Royalty-free, widely supported in browsers | Rare outside the web | |
| Apple ProRes | Pro iPhones, professional cameras and editors | Easy to edit, very high quality | Huge files; little support outside Apple and editing software | |
| MPEG-2 | H.262 | DVDs, older camcorders, broadcast recordings | Simple to decode | Inefficient by modern standards |
ffprobe -v error -show_entries stream=index,codec_type,codec_name,codec_tag_string,profile,level,pix_fmt -of compact file.mp4
The pix_fmt value in that output folds bit depth and chroma together: yuv420p is 8-bit 4:2:0, yuv420p10le is 10-bit 4:2:0 and yuv422p10le is 10-bit 4:2:2.
MP4 is only the container. If the video inside is HEVC, AV1 or 10-bit H.264, or the audio is AC-3 or DTS, a player that lacks that decoder will refuse it. Check both codecs here, then see the codec not supported guide for fixes.
Both are HEVC. hvc1 keeps the decoder setup in the file header, hev1 allows it inside the stream. Apple devices generally need hvc1, and re-wrapping with the hvc1 tag usually fixes an HEVC file that won’t open on an iPhone or Mac.
On a Mac, QuickTime’s Movie Inspector (Command-I) names the compression format. On Windows, File Explorer usually doesn’t, so use VLC’s Tools > Codec Information or open the file here, where the codec card says H.264 (AVC) or HEVC (H.265) with its tag.
The profile is the toolset the encoder used (for example High for H.264 or Main 10 for HEVC). The level caps resolution, frame rate and bitrate. A device can fail on a file whose profile or level is higher than its decoder supports, even though the codec name matches.
No, it is the same codec with a profile that allows more shades per colour channel. It does need a decoder that supports that profile, which is why 10-bit H.264 in particular fails on many phones, TVs and browsers.
No. The file is read on your device and nothing is sent anywhere. Viewing details never modifies the file; only Download new file in Edit & clean writes a new copy, and only when you ask for it.
Yes. The Audio section shows the codec (AAC, Opus, AC-3, E-AC-3, DTS, FLAC, PCM and more), the channel layout with a speaker diagram, the sample rate, bitrate and language.