FLV to MKV — Format Comparison & Online Converter
Fast, instant FLV to MKV conversion. No signup required. Just drop your .flv file and get .mkv in seconds.
Batch Settings
Generation loss — quality may degrade
FLV uses lossy compression, and so does MKV. Converting means decoding and re-encoding — each cycle can permanently degrade quality. Convert from the original source file whenever possible.
Some metadata may not survive
Your FLV file may contain FLV metadata metadata. MKV has limited or no support for these metadata types. Location data (GPS), camera settings, and color profiles may be stripped during conversion.
What compression artifacts to expect
MKV lossy compression can produce codec-dependent. At the high quality settings CocoConvert uses by default, these are usually invisible to the eye. Lower quality settings trade visual fidelity for smaller file sizes.
かつてウェブ動画の主流であったFLV形式。しかし、高画質化や多機能化が進む現代において、より柔軟で高機能なMKV形式への変換をお考えの方も多いのではないでしょうか。特に、長編のアニメ作品や記録映像など、映像と音声を高品質に保ちながら、複数の音声トラックや字幕データを統合したい場合に、MKVはその真価を発揮します。この変換ツールは、大切な映像資産を未来へと継承するための、信頼できる架け橋となることを目指しています。複雑な設定は不要で、直感的な操作でスムーズに変換が完了します。あなたの貴重なコンテンツを、より洗練されたMKV形式で保存し、様々なデバイスで快適にお楽しみください。
- アニメファンによる高画質アーカイブ
- ビジネス会議録の多言語字幕対応
- 古いガラケー動画の現代形式への移行
日本では、特にファン制作の字幕付きアニメ動画や、多言語対応が必要な企業向けコンテンツにおいて、MKVの複数トラック対応が重宝されます。FLVはかつてのニコニコ動画などで広く使われていましたが、現在はMKVの方が汎用性が高いと認識されています。
About FLV to MKV Conversion
FLV (introduced 2002) and MKV (introduced 2002) are both video formats, but they differ in important ways. FLV (Flash Video) is a legacy streaming format — converting to MP4 is recommended for modern use. MKV (Matroska) is an open container supporting virtually any codec, multiple audio tracks, and subtitles.
Full Name: FLV uses Flash Video, while MKV uses Matroska Video. Compression: FLV uses Lossy, while MKV uses Lossy. Color Depth: FLV uses 8-bit, while MKV uses 8–10 bits (codec dependent).
When you convert FLV to MKV, the goal is to improve file compatibility across devices. FLV uses lossy compression, and so does MKV. Converting means decoding and re-encoding — each cycle can permanently degrade quality. Convert from the original source file whenever possible. Understanding these technical differences helps you choose the right format for your workflow.
Your FLV file is decoded and re-encoded as MKV. The conversion involves 4 steps: (1) your flv file is uploaded and the format is validated, (2) the file content is decoded into its raw representation, (3) the data is re-encoded in mkv format with optimal settings, (4) the converted file is ready for download.
CocoConvert's converter handles the entire pipeline server-side using FFmpeg, Sharp, and qpdf — battle-tested libraries used by streaming platforms and enterprise tools. Files are encrypted in transit and deleted within 24 hours.
This conversion is ideal when you Your FLV file won't open on a recipient's device or in an application, or when you A website, service, or platform only accepts MKV uploads. For the opposite direction, CocoConvert also supports MKV to FLV conversion.
How to Convert FLV to MKV
- 1
Upload .flv file
Select your FLV file by dragging it to the upload zone or using the file picker. Batch upload is available for multiple files.
- 2
Choose .mkv
Set MKV as the output format. The converter uses optimal settings based on the FLV→MKV conversion profile.
- 3
Convert
The server-side engine decodes your FLV file and re-encodes it as MKV. Processing time depends on file size and complexity.
- 4
Download result
Grab your converted .mkv file. Multiple output files can be downloaded together.
What Happens When You Convert FLV to MKV
Your FLV video is transcoded — video and audio streams are decoded and re-encoded into the MKV container. This is a lossy process that takes time proportional to the video duration.
Your FLV file is demuxed — video, audio, and subtitle streams are separated
The video stream is decoded frame-by-frame, then re-encoded with MKV-compatible codecs (typically H.264 for MP4)
The audio stream is decoded and re-encoded (or copied if the codec is compatible)
Subtitle and chapter data is preserved where the target supports it
Streams are muxed into the MKV container and the file is saved
FLV vs MKV — Detailed Comparison
| Feature | .FLV | .MKV |
|---|---|---|
| Full Name | Flash Video | Matroska Video |
| Compression | Lossy | Lossy |
| Color Depth | 8-bit | 8–10 bits (codec dependent) |
| HDR Support | No | Yes |
| Typical File Size | 30–100 MB per minute | 50–200 MB per minute |
| Platform Support | Very Limited | Very Wide |
| Browser Support | none | Limited |
| Year Created | 2002 | 2002 |
| Open Standard | No | Yes |
Should You Convert FLV to MKV?
When to Convert
- ✓Your FLV file won't open on a recipient's device or in an application
- ✓A website, service, or platform only accepts MKV uploads
When NOT to Convert
- ✗You're converting just because the file "seems old" — re-encoding lossy-to-lossy always degrades quality
Common Mistakes When Converting FLV to MKV
"I'll convert to MKV and then back to FLV — it'll be the same"
Each lossy conversion cycle permanently degrades quality. Going FLV → MKV → FLV will produce a noticeably worse file than the original. Always keep your source file.
Frequently Asked Questions
What is the difference between FLV and MKV?
FLV (Flash Video) is a legacy streaming format — converting to MP4 is recommended for modern use. MKV (Matroska) is an open container supporting virtually any codec, multiple audio tracks, and subtitles. Full Name: FLV uses Flash Video, while MKV uses Matroska Video. Compression: FLV uses Lossy, while MKV uses Lossy. Color Depth: FLV uses 8-bit, while MKV uses 8–10 bits (codec dependent).
Does FLV to MKV conversion affect quality?
FLV uses lossy compression, and so does MKV. Converting means decoding and re-encoding — each cycle can permanently degrade quality. Convert from the original source file whenever possible.
Which format has better compression, FLV or MKV?
FLV uses lossy compression. MKV uses lossy compression. The better choice depends on whether you prioritize file size or quality.
How long does FLV to MKV conversion take?
Most conversions finish in seconds. Larger files or complex video content may take 10–30 seconds. CocoConvert processes files in parallel for batch jobs.
Is FLV or MKV better for long-term storage?
Both formats use lossy compression, so consider keeping your original source file for long-term storage.
Versions are pinned in our worker Dockerfile and re-built via CI on every change.