FLV Flash Video Format

FLV is a video file format developed by Macromedia (later acquired by Adobe Systems) for use with the Flash Player. It’s a container format that stores audio and video data in a single file.

History

The FLV format was first introduced in 1996 as part of the Macromedia Flash 3 release. Initially, it was used to store short animations and videos within Flash content. Over time, the format evolved to support more advanced features, such as streaming media and multi-bitrate encoding.

Structure

A FLV file consists of a series of frames, each containing audio and/or video data. The file structure is as follows:

  1. File Header: A 9-byte header that contains metadata about the file, including:
    • Signature (“FLV”)
    • Version number
    • Flags (e.g., compression, encryption)
  2. Frames: A series of frames, each containing:
    • Audio data (optional)
    • Video data (optional)
  3. Metadata: Optional metadata blocks that provide additional information about the file, such as:
    • Author
    • Copyright
    • Timestamps

Audio and Video Formats

FLV files can contain various audio and video formats, including:

  1. Audio:
    • MP3 (MPEG Audio Layer 3)
    • ADPCM (Adaptive Differential Pulse Code Modulation)
  2. Video:
    • Sorenson Spark (a proprietary codec developed by Macromedia)
    • On2 VP6 (a video codec developed by On2 Technologies)

Compression

FLV files use various compression algorithms to reduce the file size, including:

  1. Lossy compression: Discards some of the data to achieve a smaller file size.
  2. Lossless compression: Compresses the data without discarding any information.

Common Uses

FLV files were widely used in the past for various applications, including:

  1. Online video sharing: YouTube and other online platforms initially supported FLV as one of their primary video formats.
  2. Flash animations: FLV was often used to store animations and short videos within Flash content.
  3. Streaming media: FLV files were used to deliver streaming media content over the internet.

Decline

Although FLV was once a popular format, its usage has declined significantly since the mid-2000s. This is due in part to:

  1. Adoption of new formats: Other video formats, such as MP4 (MPEG-4 Part 14), have gained popularity and offer better compression efficiency.
  2. HTML5 and modern web standards: The introduction of HTML5 and other modern web standards has reduced the need for proprietary formats like FLV.

Today, FLV files are largely considered a legacy format, and it’s recommended to use more modern and efficient video formats instead.