FLV vs MTS
A detailed comparison of Flash Video and AVCHD Video — file size, quality, compatibility, and which format to choose for your workflow.
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Technical Specifications
| Specification | .FLV | .MTS |
|---|---|---|
| MIME type | video/x-flv | video/mp2t |
| Extensions | .flv, .f4v | — |
| Video codecs | Sorenson Spark, VP6, H.264 (F4V) | H.264 (AVCHD Main/High Profile) |
| Audio codecs | MP3, Nellymoser, AAC | AC-3 (Dolby Digital), LPCM |
| Status | Deprecated since December 31, 2020 | — |
| Extension | — | .mts |
| Container | — | BDAV MPEG-2 Transport Stream (192-byte packets) |
Strengths Comparison
.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.
.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
.FLV — 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.
- Metadata format is primitive compared to MP4 or MKV.
- Actively harmful to use today — every major security agency has warned against Flash since 2015.
.MTS — Limitations
- Slow to decode — editors typically transcode for editing.
- Proprietary folder-structure conventions complicate direct import.
- Largely legacy as smartphones replaced dedicated camcorders.
- 192-byte packet format adds overhead vs plain TS.
Frequently Asked Questions
FLV (Flash Video) is a video container format that bundles one or more video streams, audio tracks, and optional subtitles into a single file. The container format determines how metadata is organised and which codecs can live inside; the visual quality itself depends on the codec (H.264, H.265, VP9, AV1) rather than the FLV wrapper. It is part of the video files family.
MTS (AVCHD Video) is a video container format that bundles one or more video streams, audio tracks, and optional subtitles into a single file. The container format determines how metadata is organised and which codecs can live inside; the visual quality itself depends on the codec (H.264, H.265, VP9, AV1) rather than the MTS wrapper. It is part of the video files family.
VLC, MPV and PotPlayer play nearly every FLV file on desktop. Browser support varies: modern Chromium, Firefox and Safari play common containers via the HTML5 <video> tag, but niche FLV variants may fail. If a device refuses your FLV, convert to MP4 with our FLV to MP4 converter for universal playback.
VLC, MPV and PotPlayer play nearly every MTS file on desktop. Browser support varies: modern Chromium, Firefox and Safari play common containers via the HTML5 <video> tag, but niche MTS variants may fail. If a device refuses your MTS, convert to MP4 with our MTS to MP4 converter for universal playback.
Upload your FLV to KaijuConverter and pick MP4, MOV, MKV, WebM, or any other target. Our pipeline uses FFmpeg under the hood and stream-copies when codecs are compatible (no quality loss) or transcodes at high-quality defaults otherwise. Conversion runs server-side; both files delete within two hours.
Only when the target requires re-encoding. If the codecs inside FLV match what the target container supports, FFmpeg stream-copies the streams and the output is bit-identical to the source. Transcoding uses transparent quality defaults (CRF 20–23 H.264) and produces output indistinguishable from the original at normal viewing distance.
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