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FLVMeta - FLV Metadata Editor

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flvmeta is a command-line utility aimed at manipulating Adobe(tm) Flash Video files (FLV), through several commands, only one of which can be used for each invocation of the program.


Metadata injection

This program 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 optionally 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.


See the file for build and installation instructions.


Main developer


I would like to thank the following contributors:


The FLVMeta source package includes and uses the following software:


FLVMeta is provided "as is" with no warranty. The exact terms under which you may use and (re)distribute this program are detailed in the GNU General Public License, in the file

See the file for a description of major changes in this release.

See the file TODO for ideas on how you could help us improve FLVMeta.