Check your export before you post it.
Drop an MP4 or MOV to see its codec, size, frame rate, bitrate, HDR and audio, with plain-language fixes for anything likely to cause trouble: variable frame rate, HDR wash-out, the wrong shape, or a starved bitrate. The file is read on your device and never uploaded.
What the checker reads and why it matters
- Codec, profile and level: H.264 is the most widely accepted upload codec. HEVC, AV1 and VP9 are efficient but don't play everywhere. ProRes is a master format, not an upload format.
- Display size, shape and rotation: the size after the rotation flag is applied, compared with the shape you're targeting (9:16, 4:5, 1:1 or 16:9).
- Frame rate and variable frame rate: read from the file's per-frame timing table, not guessed from metadata.
- Bitrate: the actual bytes of the video track over its duration, and bits per pixel per frame. A low value means the platform's re-compression has less to work with.
- Chroma and bit depth: 4:2:2, 4:4:4 and 10-bit H.264 often fail on phones and browsers.
- Colour and HDR: BT.709 SDR, or HDR10 (PQ), HLG or Dolby Vision.
- Audio: codec (AAC-LC, HE-AAC, Opus, PCM and more), sample rate, channels, and whether the audio and video lengths match.
- Fast start: whether the index sits before the media data, so playback can begin before the file has fully downloaded.
Worked example: an iPhone clip edited on a laptop
A 40-second iPhone clip comes back as HEVC Main 10, 1080 × 1920 after a 90° rotation flag, about 29.9 fps average with a variable frame rate, HLG (HDR) colour, and AAC-LC stereo at 44.1 kHz.
That produces three things to check: HDR (it may play brighter or look washed out depending on the app), variable frame rate (some editors drift audio), and HEVC (some browsers and Windows editors can't preview it). For an SDR delivery, use your editor's colour-managed SDR export and review the result. The tool withholds a generic FFmpeg command for HDR because a codec change alone does not perform tone mapping.
How the bitrate check works
Bits per pixel per frame = video bitrate ÷ (width × height × frame rate). For a 1080 × 1920, 30 fps H.264 file at 6 Mbps that is 6,000,000 ÷ 62,208,000 ≈ 0.096. The tool flags H.264 below 0.05, and HEVC, AV1 or VP9 below 0.03. These are Creator Lane's rule-of-thumb floors for detailed footage, not platform requirements. A static talking head can look fine below them, and fast motion can need more.
bpp = bitrate / (width × height × fps)
= 6,000,000 / (1080 × 1920 × 30)
≈ 0.096 → OK for H.264 (floor 0.05)Limitations
- It reads metadata and the frame index. It does not decode frames, so it can't see blur, banding, black frames, or audio that is silent but present.
- Missing colour tags are reported as unknown, not SDR. If stream inspection cannot complete, the report warns that container tags alone may miss HDR.
- Thresholds are editorial heuristics. Instagram, TikTok and YouTube re-encode uploads and don't publish pass/fail rules for creator uploads, so passing every check doesn't guarantee how a post looks or performs.
- Variable frame rate is judged from the timing table. A file with a single odd frame duration is treated as constant.
- Full checks cover MP4, MOV, M4V and 3GP. WebM and MKV get a basic size and duration check only.
Questions
›Does my video get uploaded?
No. The page reads the file's index and stream metadata directly from your device using the browser's File API and a locally running MediaInfo engine. It does not upload your video. Large files are read in chunks; speed depends on the file and your device.
›How do I tell if my video has a variable frame rate?
Drop the file in and read the Frame rate check. The tool counts how many frames share the same duration in the file's timing table. If more than about 1% of frames differ, it reports a variable frame rate and the average. Phone and screen recordings often do this, and some editors then drift audio out of sync.
›How do I know if my video is HDR?
The tool reads container and video-stream colour metadata. PQ or HLG transfer tags, or a Dolby Vision configuration, indicate HDR. Missing or unreadable tags do not establish that the video is SDR. Confirm the source and your editor's colour-management settings before converting HDR to SDR.
›What export settings should I use for Instagram Reels?
There is no single correct preset, and Instagram re-encodes every upload. A practical starting point for vertical video is H.264, 1080 × 1920 (9:16), the frame rate you filmed at (constant), SDR colour, and AAC stereo audio at 48 kHz. The checker flags departures from that and explains the trade-off. It does not promise more reach or quality.
›Which files can it read?
The full check reads MP4, MOV, M4V and 3GP (ISO base media files), including fragmented MP4. For WebM, MKV and other containers it shows what the browser can tell (dimensions and duration) and whether this browser can play the file.
›Is this the same as MediaInfo?
It uses MediaInfo locally for stream colour information alongside its MP4 index reader, then adds creator-focused checks. The full MediaInfo application reads more containers and fields. Use it when you need the complete technical dump.
›Can I share the result with my editor or an AI assistant?
Yes. Download or copy the Markdown report, or copy the JSON. It lists every value the tool read and every check with its fix, so someone else can act on it without the original file.
Sources and related guides
Checks and heuristics reviewed November 4, 2026. Platform behaviour changes; re-check a test upload.
About this tool
A free, in-browser inspector for exported MP4, MOV and M4V files. It reads codec configuration, track headers, sample timing and size tables, and colour metadata, including stream tags through MediaInfo. It reports the detected values and compares them with practical delivery heuristics for vertical, square, portrait and landscape posts. File reads stay on your device; nothing is uploaded.
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