Fork me on GitHub

FLVMeta - FLV Metadata Editor


flvmeta is a command-line utility aimed at manipulating Adobe(tm) Flash Video files (FLV).

A complete Changelog can be found on Github.


Metadata injection

It has the ability to compute and inject a variety of values in the onMetaData event tag, including keyframe indices used by most video players to allow random-access seeking, notably for HTTP pseudo-streamed files via a server-side module, by having the client send the file offset looked up for the nearest desired keyframe.
Tools such as flvmeta must be used in the case the initial encoding process is unable to inject those metadata.

It can also optionnally inject the onLastSecond event, used to signal the end of playback, for example to revert the player software to a 'stopped' state.

File information and metadata dumping

flvmeta also has the ability to dump metadata and full file information to standard output, in a variety of textual output formats, including XML, YAML, and JSON.

File validity checking

Finally, the program can analyze FLV files to detect potential problems and errors, and generate a textual report in a raw format, or in XML. It has the ability to detect more than a hundred problems, going from harmless to potentially unplayable, using real world encountered issues.


flvmeta can operate on arbitrarily large files, and can handle FLV files using extended (32-bit) timestamps. It can guess video frame dimensions for all known video codecs supported by the official FLV specification.

Its memory usage remains minimal, as it uses a two-pass reading algorithm which permits the computation of all necessary tags without loading anything more than the file's tags headers in memory.

Supported platforms

FLVMeta has been successfully compiled and tested on the following platforms:

Generally, this program should compile cleanly and run on any 32-bit or 64-bit platform provided there is a working C compiler with a reasonably complete implementation of the C standard library.


Please read the man page.


FLVMeta is distributed under the terms of the GNU General Public License v2.0.


Development is done at Github. Please feel free to clone the flvmeta repository and hack the source code as you want. Submitted issues and pull requests are carefully reviewed.

The author can be contacted directly either by , or on IRC, at #flvmeta on Freenode.

The Google Code project is kept for historical reasons, but it should not be used anymore, except to download the releases (until Google Code stops supporting downloads completely in 2014).