Video to FLV Converter

How to Convert Video to FLV Online

1. Upload Your Video File: Drag and drop or click "+ Add Files" to load MP4, MOV, MKV, AVI, WMV, WebM, MPEG, 3GP, MTS, VOB, OGV, RM, or any of 35+ supported video formats. Batch conversion is supported.
2. Pick Codec, Preset, and File Compression: The default writes an FLV container with H.264 video and AAC audio (FLV's modern profile). Switch the codec to FLV1 (Sorenson Spark) or VP6 (Flashsv/Flashsv2) for true legacy Flash compatibility, or leave H.264 for the smallest, sharpest output. Use the Preset dropdown (Lowest through Very High) for fast quality control, or open File Compression to set Constant Bitrate, Constant Quality (CRF), or Specific file size in MB or KB.
3. Resolution and Trim (Optional): Pick a Preset Resolution (4320p, 2160p, 1440p, 1080p, 720p, 576p, 480p, 360p, 240p, 144p), enter a custom Width x Height, scale by Resolution Percentage, or leave Keep original. Use Trim → Time Range to clip a start/end before encoding.
4. Convert and Download: Click "Convert". Files are processed on our servers and deleted automatically after a few hours — no sign-up, no watermark, no FFmpeg install.

Why Convert Video to FLV?

FLV (Flash Video) was Adobe's container for online streaming from roughly 2002 onwards, and despite Adobe ending official Flash Player support on December 31, 2020, FLV remains widely used as a transport and ingest format. Modern FLV files no longer rely on the Flash plugin: VLC, MPV, FFplay, mpv-based players, and even YouTube's encoder pipeline still read FLV streams natively. Converting to FLV makes sense when you need to feed a system that specifically expects this container.

• RTMP live-streaming ingest — Twitch, YouTube Live, Facebook Live, Restream, and most CDNs still ingest video over RTMP, which carries FLV-tagged H.264/AAC packets. Local recordings written as .flv drop straight into OBS replay pipelines and re-stream tools without re-muxing.
• Legacy e-learning, LMS, and SCORM packages — Articulate Storyline, older Moodle plugins, Adobe Captivate exports, and corporate LMS bundles built before 2018 often expect FLV assets; replacing them in-place avoids re-authoring entire courses.
• Embedded media in CD/DVD archives and museum kiosks — Standalone Flash Projector executables (.exe / .app) keep working offline because they ship their own runtime; FLV is still the supported asset format for those builds.
• Smaller files than uncompressed AVI or MOV — An H.264-in-FLV mux is typically 10x smaller than DV AVI for the same resolution and roughly matches an MP4 of the same bitrate within a few percent.
• Game-engine cutscenes and older middleware — Bink/Scaleform, RAD Video Tools, and legacy Unity video plugins consume FLV for cutscenes and in-game video panels.
• Archive playback of recorded VOD — If you have old Twitch VODs, Justin.tv exports, or screen recordings from circa 2010-2018 Camtasia/ScreenFlow, FLV is often the round-trip format that preserves the original RTMP recording without re-encoding.

For most general web playback you should pick MP4 — see Convert Video to MP4 or FLV to MP4 for the reverse direction.

FLV vs MP4 — Format Comparison

FLV Codec and Quality Guide

For quality presets, Very High targets visually lossless at typical streaming bitrates, High maps to a CRF around 20-23 (broadcast-grade), Medium is fine for 720p web playback, and Low/Lowest trades quality for small file size — useful for proxy uploads or bandwidth-limited testing. If you need a specific output size (e.g., a 25 MB attachment limit), use File Compression → Specific file size, and the encoder will pick a bitrate to hit that target.

Frequently Asked Questions

Why would I still convert anything to FLV in 2026?

Almost always one of two reasons: you're feeding an RTMP encoder/recorder that writes .flv natively (OBS replay buffers, Twitch local recording, Wirecast, vMix), or you're maintaining a legacy LMS/CD-ROM/kiosk system that requires FLV assets. For ordinary web or mobile playback, convert to MP4 instead — every modern browser, phone, and TV plays MP4 natively, and FLV has been removed from all major browsers since the Flash sunset on December 31, 2020.

Do I need Adobe Flash Player installed to play the FLV file?

No. Adobe Flash Player reached official end-of-life on December 31, 2020 and Adobe began blocking Flash content on January 12, 2021. Today's FLV files are decoded by standalone players: VLC, MPV, PotPlayer, FFplay, IINA on macOS, and most non-browser media frameworks. The container outlived the plugin.

Which codec should I pick — H.264, VP6, or Sorenson Spark (FLV1)?

Pick H.264 unless a downstream tool specifically refuses it. H.264 in an FLV container is exactly what Twitch and YouTube Live ingest over RTMP, and it gives the best quality-per-byte. VP6 is the right choice for legacy Articulate / Captivate / SCORM 1.2 LMS packages built between roughly 2006 and 2015. FLV1 (Sorenson Spark, a proprietary H.263 variant) is only needed for the oldest Flash Player 6-7 era assets — its compression is much weaker than H.264 or even VP6.

Will the converted FLV file work in OBS, vMix, and Wirecast?

Yes for H.264-in-FLV — those tools were built around the same RTMP/FLV pipeline that Twitch and YouTube Live use, so an H.264 FLV imports as a clean source. VP6 and FLV1 also load but may show a warning about deprecated codecs. If you're feeding the FLV into a live stream, keep audio as AAC at 48 kHz — most ingest servers reject other audio rates.

Are audio tracks preserved during conversion?

Yes. We default to AAC inside the FLV container (modern profile), which matches what every RTMP server expects. The legacy FLV-supported audio codecs — MP3, Nellymoser Asao, Speex, and ADPCM — are also available in the audio codec dropdown if a downstream tool requires them. Stereo, sample rate, and bitrate are configurable in Advanced Options.

What's the maximum file size and how long does conversion take?

Files up to 4 GB process on a single upload. Conversion time is dominated by the video codec choice: H.264 with the Very High preset on a 10-minute 1080p source typically completes in 60-120 seconds on our pipeline; VP6 and FLV1 are slower (older single-threaded encoders). You can shrink work by setting Resolution Percentage to 50% or picking a lower Preset Resolution before queuing.

Can I trim the video before converting to FLV?

Yes — open Trim in Advanced Options and choose Time Range, then enter the start and end timestamps in HH:MM:SS.ms. Only the trimmed segment is encoded, which speeds up the job and avoids re-trimming in a separate editor. If you only need to cut a segment without changing the codec or bitrate, use the dedicated Trim FLV page.

Why does my FLV look softer than the source MP4?

Two common causes: (1) you picked the Low or Medium preset, which targets a smaller bitrate; bump it to High or Very High. (2) you selected VP6 or Sorenson Spark — both are objectively weaker than H.264 at the same bitrate. For best visual quality, keep the codec on H.264 and set Constant Quality to CRF 18-20. If you need an even smaller file, see Compress FLV after conversion.

Is the conversion lossless?

No — both VP6 and H.264 (the practical FLV codecs) are lossy. If your source is already H.264 at moderate bitrate, re-encoding to H.264-in-FLV at Very High keeps quality close to the original but still loses a small amount of detail; this is inherent to lossy video codecs. The container itself (FLV) is just packaging and doesn't add loss.