Video Container Inspector
Look inside a local media container rather than watching or compressing it. The browser reads track headers and a bounded prefix of encoded packet metadata. For ordinary, non-fragmented MP4, it also reads stts/ctts sample tables to show raw media-time DTS and composition PTS. It makes no claim that an out-of-order presentation timestamp proves a specific picture is a B-frame.
Key features
- List every detected video and audio track with codec and native container codec ID
- Show MP4 sample-table DTS beside packet presentation timestamps and decode order
- Mark presentation backsteps consistent with reordered pictures, without guessing exact B-frame type
- Report video color primaries, transfer, matrix, range and HDR as exposed by Mediabunny
- State missing video/audio tracks and unavailable timing fields explicitly
- Export the inspected packet prefix as CSV and the full inspection as JSON
How to use
- Select a local MP4/MOV or WebM/MKV file, or create the encoded example.
- Run inspection and read the container summary and missing-track notices.
- Choose a track to inspect codec, color/audio fields, and packet timing.
- Compare decode index with PTS and, for supported MP4, raw DTS and composition PTS.
- Download CSV or JSON if you need an audit record.
Use cases
- Check why a file has no audio track before editing
- Compare display order with decode order in a camera export
- Inspect codec IDs and color tags before sharing a clip
- Document timing evidence from a local MP4 without transcoding
Frequently asked questions
Does this tool play, repair or compress the video?
No. It only reads the container and encoded packet metadata. Playback and compression are separate tools.
Does DTS appear for every file?
No. Raw media-time DTS is parsed only from complete stts/ctts sample tables in ordinary non-fragmented MP4/MOV. WebM/Matroska and fragmented or unsupported MP4 timing show an unavailable value. Mediabunny's packet PTS may include edit-list or timeline normalization, so it can differ from the raw MP4 composition PTS.
Can the inspector identify every B-frame?
No. A PTS backstep in decode order is evidence of presentation reordering often associated with B-frames, but packet key/delta flags and timing alone do not identify every picture type. No bitstream-level frame-type claim is made.
What if an audio or video track is missing?
The report states the missing track explicitly and still shows any other tracks. A container with no tracks or an unreadable header is rejected.
Are color values guaranteed to be explicit file tags?
No. These are values returned by Mediabunny's track color-space API and may be normalized or inferred by the library. The tool does not expose raw colr/Matroska elements or guarantee display appearance.
Why are only some packets shown?
The inspector reads metadata for at most the first 400 packets of each of up to 12 tracks, and caps files at 256 MiB and MP4 moov parsing at 24 MiB. The UI marks a truncated prefix. It does not claim a whole-file packet audit.
Privacy
The selected bytes stay in this browser. The inspector does not upload, decode, play, re-encode, modify or store the source file. CSV and JSON are created only when you request a download.
Comments & questions