CONVERT
MTS → FLV
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Fast, secure MTS to FLV conversion. No registration required.
Setup: MTS is the AVCHD camcorder variant of the MPEG transport stream. Goal: an interchangeable FLV. A MTS 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 MTS with the same codec inside. Uploading above triggers a stream-level rewrap when possible, keeping the visible quality identical to the source. One more beat. MTS is the AVCHD camcorder variant of the MPEG transport stream. Receiving format: FLV is the Adobe Flash Video container, now deprecated but still lingering in archives.
AVCHD Video
Source formatMTS (AVCHD) is a high-definition video format from Sony and Panasonic camcorders.
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.
Why convert MTS to FLV
Sending MTS 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.
HOW TO CONVERT
MTS → FLV
Drop the video file
Select a MTS 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.
Common Use Cases
Share across platforms
Send FLV files to anyone without worrying about whether they have the right software for MTS.
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 MTS 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.
MTS vs FLV — Strengths and limitations
What each format does best, and where it falls short.
MTS Strengths
- Native format for every AVCHD camcorder since 2006.
- H.264 compression — small files for high-def quality.
- Direct compatibility with iMovie, Premiere, Resolve, Final Cut.
- Carries Dolby Digital 5.1 audio on flagship camcorders.
Limitations
- Slow to decode — editors typically transcode for editing.
- Proprietary folder-structure conventions complicate direct import.
- Largely legacy as smartphones replaced dedicated camcorders.
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.
MTS vs FLV — Technical specifications
Side-by-side comparison of the technical details.
MTS
- MIME type
- video/mp2t
- Extension
- .mts
- Container
- BDAV MPEG-2 Transport Stream (192-byte packets)
- Video codecs
- H.264 (AVCHD Main/High Profile)
- Audio codecs
- AC-3 (Dolby Digital), LPCM
FLV
- MIME type
- video/x-flv
- Video codecs
- Sorenson Spark, VP6, H.264 (F4V)
- Audio codecs
- MP3, Nellymoser, AAC
- Extensions
- .flv, .f4v
- Status
- Deprecated since December 31, 2020
| Specification | MTS | FLV |
|---|---|---|
| MIME type | video/mp2t | video/x-flv |
| Extension | .mts | — |
| Container | BDAV MPEG-2 Transport Stream (192-byte packets) | — |
| Video codecs | H.264 (AVCHD Main/High Profile) | Sorenson Spark, VP6, H.264 (F4V) |
| Audio codecs | AC-3 (Dolby Digital), LPCM | MP3, Nellymoser, AAC |
| Extensions | — | .flv, .f4v |
| Status | — | Deprecated since December 31, 2020 |
MTS vs FLV — Typical file sizes
Approximate file sizes for common scenarios.
MTS
- 1 min HD AVCHD (17 Mbps) ~130 MB
- 1 hour AVCHD Full HD ~8 GB
FLV
- 10-min YouTube 2008-era video 40-80 MB
- 45-min TV show (FLV H.264) 200-500 MB
Quality & Compatibility
Resolution, frame rate and colour space are preserved end-to-end. If the FLV container does not support some MTS 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 MTS 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 MTS chapters — check before relying on them.
Frequently Asked Questions
Only when it has to. If the codecs inside MTS (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".
Related comparisons
See these formats side by side to understand which fits your use case best.
Related Guides
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