webm-meta-lite Demo

How to read the results

Most of the fields below are reported exactly as stored in the WebM file: info (timecodeScale, muxingApp, writingApp) and tracks are read straight from the file header, without any post-processing. Two fields are produced by the library rather than read from the file: fileSize is the size of the file itself, and mimeType is assembled from the codec IDs of the tracks.

durationMilliSeconds is the only resolved value. Up to three methods are tried in order, stopping at the first one that yields a value:

1. Header — the Duration element of the file header. Exact, but missing in files written by MediaRecorder and other live muxers.
2. Cues — the last entry of the Cues index. An estimate: it points at the last indexed cluster, not at the end of the last frame.
3. Tail — the last Cluster/Block timecode found by scanning the end of the file. Also an estimate: it excludes the play time of the last frame itself.

The method that produced the value is reported as durationSource and is shown above each result below.