VIDEOZ

MP4 · HLS · FLV · Media inspector

FLV file analyzer and tag viewer

Drop an FLV file to list every audio, video and script tag with its timestamp, size and byte offset, the video codec and keyframe flags, and the onMetaData values written by the encoder. The parser is plain TypeScript running in your browser, so large recordings and live-stream captures open quickly.

Drop an FLV file or click to browse

click or drag & drop

FLV structure in brief

An FLV file is a 9-byte header followed by a sequence of tags. Each tag has a type (8 = audio, 9 = video, 18 = script data), a 24-bit data size and a timestamp in milliseconds. The first script tag is usually onMetaData, an AMF0 object with duration, width, height, frame rate and codec IDs.

Typical uses

  • Debug RTMP and live-stream recordings: look for timestamps that jump backward, gaps, or audio and video drifting apart
  • Measure the keyframe interval from video tags marked as keyframes
  • Check that onMetaData matches the actual stream (duration, resolution, codec)
  • Identify the video codec: H.264 (AVC), HEVC, VP6, Sorenson H.263 and others

Frequently asked questions

Are my video files uploaded?
No. MP4 and FLV files are read and parsed inside your browser tab with JavaScript and WebAssembly; the file never leaves your device. The only thing that goes through the VideoZ server is an HLS playlist URL, which is fetched by a small proxy because browsers block cross-origin playlist requests.
Can it open very large FLV files?
Yes. Parsing is plain TypeScript with no WebAssembly, and the tag list is paginated, so files with millions of tags stay responsive.
What is onMetaData?
onMetaData is an AMF0-encoded script tag the encoder writes at the start of an FLV, describing duration, dimensions, frame rate, bitrates and codecs.

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