Convert FLV to WMV — Free & Private

Will my video be re-encoded or just remuxed when converting FLV to WMV?

Always re-encoded, no matter which codec your FLV file uses. WMV requires Windows Media Video's own VC-1/WMV3 codec, and neither of the two codecs found in FLV files — H.264 (common in FLV files made after 2008) or the older VP6/Sorenson H.263 (common in early Flash video) — can be placed inside a WMV container as-is. Convertlo decodes your FLV's video and audio and re-encodes both into VC-1 and WMA.

• H.264-in-FLV → WMV: full re-encode to VC-1, no shortcut available
• VP6/Sorenson-in-FLV → WMV: full re-encode, same as above
• Re-encoding takes longer than a remux but lets you pick a target bitrate
• WMV is the only one of our video targets that never offers a remux path from FLV

Does converting FLV to WMV reduce quality?

Yes — both H.264 (FLV's codec) and VC-1 (WMV's codec) are lossy, so any re-encode between them causes a second generation of quality loss, even if small at moderate bitrates.

• FLV H.264 → WMV VC-1: both are lossy codecs, so artefacts from FLV are "baked in" before VC-1 compression adds its own
• To minimize loss, use the highest bitrate the destination tool accepts
• Older FLV with Sorenson Spark codec loses more quality than H.264 FLV at the same output bitrate

How much will the file size change going from FLV to WMV?

Usually a modest reduction, though it depends on which codec your FLV used. H.264-in-FLV converted to VC-1 tends to land close to the original size, sometimes slightly smaller. VP6/Sorenson-in-FLV — the less efficient legacy Flash codec — often shrinks more noticeably once re-encoded to VC-1, since VC-1 compresses better than VP6.

• H.264-in-FLV → WMV: roughly similar size, occasionally a little smaller
• VP6/Sorenson-in-FLV → WMV: typically smaller, VC-1 is more efficient than VP6
• Bitrate settings during re-encoding have more impact on size than the codec swap itself
• For the smallest possible file, MP4 (H.264) or WebM (VP9) usually beat WMV

Why does my old FLV file stop playing on modern devices?

FLV was the native format of Adobe Flash Player, and Flash Player was permanently discontinued on December 31, 2020. Every browser removed its Flash plugin, so FLV files that once played inline on websites no longer open anywhere without a dedicated media player.

• No browser has played FLV directly since the Flash shutdown
• Phones and smart TVs were never built with FLV support
• Converting to WMV gives the file a home on Windows Media Player and VLC
• For playback on phones, browsers, and streaming devices too, MP4 is the better target