An Adobe Flash-based video format once dominant for web streaming video
FLV (Flash Video) is a container format developed by Adobe Systems for delivering video content over the internet using Adobe Flash Player. Introduced in the early 2000s, FLV quickly became the standard for web video streaming due to Flash Player's widespread adoption, powering video delivery for early versions of YouTube, Vimeo, and many other streaming websites.
The format was designed specifically for efficient delivery of video content over the web, with features that made progressive downloading and streaming more effective than previous solutions. FLV files typically contain video encoded with codecs like Sorenson Spark or VP6, and later, H.264, along with audio often encoded in MP3 or AAC formats.
Following Adobe's announcement of Flash's end-of-life in 2017 and its official discontinuation in December 2020, FLV's usage has significantly declined in favor of more modern formats like MP4 and WebM. While still encountered in various legacy contexts, FLV is now primarily a historical format that played a crucial role in the evolution of online video.
FLV uses a tagged architecture where video and audio data are divided into packets with specific tags identifying the content type, size, and timestamp. This structure facilitated the progressive downloading capability that made FLV popular for web streaming—allowing viewers to begin watching videos before the entire file had downloaded. The format also includes metadata capabilities for storing information about the video content, duration, and other attributes, which helped video platforms provide better playback experiences.
Despite Flash's discontinuation, there remains a significant volume of historical content in FLV format, particularly from the 2000s and early 2010s. Educational materials, archived webcasts, corporate training videos, and early web animations are often still found in FLV format. Accessing this legacy content sometimes requires specialized players or conversion to modern formats. Many institutions are engaged in ongoing efforts to preserve and migrate important FLV content to ensure long-term accessibility.
Some older enterprise systems, educational platforms, and specialized applications still rely on FLV-based video playback. Organizations with significant investments in Flash-based learning management systems, presentation tools, or custom applications may continue to use FLV internally, particularly if migration costs are prohibitive. These systems often operate in controlled environments where Flash Player can still be deployed, despite its removal from public-facing web browsers.
Many organizations maintain video archives that include content in FLV format. Media companies, educational institutions, and corporate archives often house collections of FLV files from the era when Flash dominated web video. While active conversion efforts are common, the original FLV files are frequently retained for archival purposes. Video historians and digital preservation specialists work with these formats to ensure historically significant content remains accessible.
In some international markets where older technology stacks remain in use, FLV content can still be encountered more frequently than in regions with faster technology adoption cycles. Certain regional websites, applications, and services that were heavily invested in Flash technology may have been slower to transition away from FLV, particularly in areas where internet infrastructure or device penetration favored Flash's efficient delivery model over newer standards.
FLV files are often encountered as source material for conversion projects. Content creators, archivists, and media managers regularly convert historical FLV files to modern formats like MP4 or WebM to ensure continued accessibility. The migration from FLV to current standards represents a significant aspect of digital preservation work, particularly for content created during Flash's dominant period in web video history.
Modern web browsers have phased out Flash Player support:
FLV files can still be played in various applications:
FLV has varying support across platforms:
Many tools can convert FLV to modern formats:
| Feature | FLV | MP4 | WebM | AVI | MOV |
|---|---|---|---|---|---|
| Current Relevance | |||||
| Web Compatibility | |||||
| Mobile Support | |||||
| Compression Efficiency | |||||
| Streaming Capability | |||||
| No Plugin Required | |||||
| Open Standard |
FLV has been largely superseded by modern formats, particularly in web contexts. MP4 offers excellent compatibility across platforms and devices with good compression. WebM provides superior compression efficiency with growing adoption, especially for web use. AVI is another legacy format with limited modern relevance but better desktop compatibility than FLV. MOV is primarily used in professional video contexts with strong support in the Apple ecosystem.
Converting FLV to MP4 is the most common and practical conversion path for modernizing legacy Flash content. Use a reliable converter like FFmpeg, HandBrake, or Adobe Media Encoder. When converting, choose H.264 for video and AAC for audio for maximum compatibility. For best results, use two-pass encoding with an appropriate bitrate to balance quality and file size. If the original FLV used older codecs like VP6, expect some quality loss during transcoding. Check the converted file's metadata, as some converters might not properly transfer information like title, duration, or creation date.
Converting FLV to WebM creates files optimized for modern web delivery with superior compression. Use FFmpeg or specialized WebM encoders, selecting VP9 video and Opus audio codecs for best quality-to-size ratio. WebM is ideal for web applications where smaller file sizes are critical, though encoding times are typically longer than MP4 conversion. For web video players that support multiple formats, consider creating both MP4 and WebM versions to leverage the superior compression of WebM in compatible browsers while maintaining MP4 for broader compatibility.
When converting FLV for archival purposes, prioritize quality over file size. Consider using lossless or minimally compressed codecs if storage permits. Document the original FLV specifications, including codec information, metadata, and any interactive features that may be lost in conversion. For important archives, maintain the original FLV alongside converted versions. If the FLV contains interactive elements or cue points, note that these features will typically be lost during conversion to standard video formats unless special accommodations are made.
Some FLV files contain embedded content beyond simple video and audio, such as cue points, subtitles, or interactive elements. Specialized tools like YAMB (Yet Another MetaData Browser) or custom scripts using the FLVTool2 library can help extract this data before conversion. For complex Flash applications that use FLV, consider screen recording the playback as a last resort to capture interactive elements that won't survive direct conversion.
Older FLV files may suffer from corruption, incomplete headers, or other issues. When standard conversion fails, try repair tools like FLV Repair Tool or use FFmpeg with special parameters like -ignore_error to skip problematic sections. For partially corrupt files, extracting and re-encoding just the video or audio streams separately may recover usable content. Sometimes adjusting the starting point for conversion can bypass header corruption issues.
For large collections of FLV files requiring conversion, batch processing tools can save time. FFmpeg can process multiple files through command-line scripting, while applications like XMedia Recode, Handbrake (with queue), or Adobe Media Encoder offer graphical interfaces for batch operations. Consider organizing files by similar characteristics (resolution, source, etc.) before batch processing to apply appropriate settings to each group.