CONVERT AVI → FLV (AVI to FLV)
Fast, secure AVI to FLV conversion. No registration required.
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HOW TO CONVERT AVI → FLV
Drop the video file
Select a AVI file. We read the container and stream descriptors to plan the conversion.
FFmpeg handles the repackage
When codecs align, FFmpeg rewraps the existing streams into a FLV container — no quality loss, near-instant finish.
Retrieve the FLV
The FLV download is ready in seconds for stream-copy jobs, minutes for full transcodes.
Situation. AVI is the legacy Microsoft Audio Video Interleave container from the 1990s. Solution: a FLV, produced below. A AVI to FLV conversion makes a recording portable. Video containers matter more than you might expect: players that handle FLV natively sometimes stutter or flat-out reject AVI with the same codec inside. Uploading above triggers a stream-level rewrap when possible, keeping the visible quality identical to the source. Background. AVI is the legacy Microsoft Audio Video Interleave container from the 1990s. Destination side, FLV is the Adobe Flash Video container, now deprecated but still lingering in archives.
Why convert AVI to FLV
Sending AVI to someone on a non-matching operating system frequently leads to "file cannot be opened". FLV avoids that by sitting in the middle of everyone's compatibility list. The repackage runs quickly and without generational loss when codecs already align.
AVI vs FLV — Technical specifications
Side-by-side comparison of the technical details.
AVI
- MIME type
- video/x-msvideo
- Extension
- .avi
- Container
- RIFF
- Max file size
- 2 GB (original); 4 GB (OpenDML extension)
- Codec support
- Any codec via FourCC identifiers
- MIME Type
- video/x-msvideo
- Category
- Video Files
- Full Name
- AVI Video
- Conversion Engine
- FFMPEG
FLV
- MIME type
- video/x-flv
- Extension
- .flv
- MIME Type
- video/x-flv
- Category
- Video Files
- Full Name
- Flash Video
- Conversion Engine
- FFMPEG
- Extensions
- .flv, .f4v
- Video codecs
- Sorenson Spark, VP6, H.264 (F4V)
- Audio codecs
- MP3, Nellymoser, AAC
- Status
- Deprecated since December 31, 2020
| Specification | AVI | FLV |
|---|---|---|
| MIME type | video/x-msvideo | video/x-flv |
| Extension | .avi | .flv |
| Container | RIFF | — |
| Max file size | 2 GB (original); 4 GB (OpenDML extension) | — |
| Codec support | Any codec via FourCC identifiers | — |
| MIME Type | video/x-msvideo | video/x-flv |
| Category | Video Files | Video Files |
| Full Name | AVI Video | Flash Video |
| Conversion Engine | FFMPEG | FFMPEG |
| Extensions | — | .flv, .f4v |
| Video codecs | — | Sorenson Spark, VP6, H.264 (F4V) |
| Audio codecs | — | MP3, Nellymoser, AAC |
| Status | — | Deprecated since December 31, 2020 |
AVI vs FLV — Strengths and limitations
What each format does best, and where it falls short.
AVI Strengths
- Simple, well-documented format — trivial for any video library to parse.
- Universal Windows playback since Video for Windows in 1992.
- Low encoding overhead — interleaved structure is fast to write.
- Works with any codec technically, including modern ones.
Limitations
- Aging container — no native support for chapters, subtitles, or multi-audio selection.
- File-size limits (2 GB original, 4 GB with OpenDML) break for HD content.
- Variable-framerate video causes sync drift.
FLV Strengths
- Low overhead — the container is extremely compact.
- Designed for streaming — progressive download and seeking work well.
- Decoded natively by Flash Player on every OS for 20 years.
Limitations
- Flash Player is dead — no modern browser can play FLV without conversion.
- Legacy codecs (Sorenson, VP6) are poorly supported in modern tooling.
- Hardware video decoders never added FLV support.
Quality & Compatibility
Resolution, frame rate and colour space are preserved end-to-end. If the FLV container does not support some AVI features (chapters, multiple subtitle tracks, DRM-protected streams), those are flattened or dropped with a warning. Hard-coded subtitles in the video frames always survive.
Tips for Best Results
- Embedded subtitle tracks convert between AVI and FLV when both containers support the same subtitle codec; otherwise burn the subtitles into the video first.
- For portrait (9:16) clips, make sure the FLV encoder preserves the correct display aspect ratio — some players default to 16:9 if SAR is ambiguous.
- Long recordings (over an hour) benefit from chapter metadata; FLV may not preserve AVI chapters — check before relying on them.
Frequently Asked Questions
Only when it has to. If the codecs inside AVI (usually H.264 or H.265 for video, AAC for audio) are accepted by FLV, we stream-copy — the bytes are repackaged into the new container with zero re-encoding and no quality loss. When the source uses a codec the target does not support, we transcode at a matching bitrate to keep the visual quality close to the original.
With stream copy, expect the job to finish in seconds to tens of seconds regardless of video length — the work is mostly rewriting the container. Transcoding is slower (roughly real-time: a ten-minute clip takes about ten minutes) because every frame must be decoded and re-encoded. The progress bar shows which mode applies.
Yes. Resolution, frame rate, colour space and bit depth are preserved by default; stream copy is literally bit-identical on these parameters. If you explicitly pick a lower bitrate or a different codec in Advanced, the output is rebuilt to those settings, but the default is always "match the source".
AVI Video
Source formatAVI is a legacy Microsoft multimedia container that stores audio and video data. While largely superseded by modern formats, it remains widely recognized and is produced by many older devices and screen recorders.
Flash Video
Target formatFLV was the dominant web video format during the Flash era. While Flash is now deprecated, many legacy video files still exist in FLV format and need conversion to modern formats.
Going the other way? Convert FLV back to AVI with the same engine.
Common Use Cases
Share across platforms
Send FLV files to anyone without worrying about whether they have the right software for AVI.
Embed in documents
Drop FLV output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
FLV often produces smaller files than AVI for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
AVI vs FLV — Typical file sizes
Approximate file sizes for common scenarios.
- 10-min video (XviD / MP3) 100-200 MB
- 45-min TV episode (DivX) 350-700 MB
- 2-hour movie (DVD rip) 700 MB - 1.4 GB
- 10-min YouTube 2008-era video 40-80 MB
- 45-min TV show (FLV H.264) 200-500 MB
Working with 4K/8K Video or Files Over 100MB?
Web browsers impose strict RAM limits on media streams. For gigabyte 4K/8K footage, GPU-accelerated NVENC transcode, or batch subtitle muxing, dedicated desktop encoders deliver zero upload delays.
One-time payment with zero recurring commitment: convert files up to 1 GB, OCR, PDF/A, and .ZIP batches for 24 hours.
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High-throughput enterprise pipeline for files up to 2,048 MB, 50-file batches, ISO PDF/A, and priority processing.
Uncapped 4K/8K multi-track transcoding with hardware NVENC, VideoToolbox, and AV1/HEVC pipelines.
10-bit color grading workflows, Apple ProRes mastering, and automated watch-folder queues.
Related comparisons
See these formats side by side to understand which fits your use case best.
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