MyMediaTools

Convert MTS to M2TS — Free Online Tool

Convert MTS files from Sony or Panasonic AVCHD camcorders into M2TS, the Blu-ray BDAV transport stream format, using H.264 video and AAC audio. This conversion restructures the MPEG-2 Transport Stream into Blu-ray-compatible BDAV packaging, making your camcorder footage ready for Blu-ray authoring software and high-definition playback pipelines.

FFmpeg Command

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How It Works

MTS and M2TS are closely related formats — both use MPEG-2 Transport Stream as their underlying container, and both commonly carry H.264 video. However, MTS uses the raw AVCHD transport stream structure as recorded by camcorders, while M2TS adds the BDAV (Blu-ray Disc Audio-Video) wrapper with additional timing and multiplexing headers required by Blu-ray players and authoring tools. Because the video codec (H.264 via libx264) is the same in both formats, the video stream is re-encoded at CRF 23 to ensure clean output, and the audio — which in AVCHD is often AC-3 or AAC — is encoded to AAC at 128k for broad compatibility. The result is a properly structured M2TS file that Blu-ray authoring applications, media servers, and standalone Blu-ray players can correctly parse and index.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg application, the open-source multimedia processing engine that powers this conversion. In the browser, this runs as FFmpeg.wasm compiled to WebAssembly — no installation required.
-i input.mts Specifies the input file — your AVCHD camcorder recording in MTS format. FFmpeg reads the MPEG-2 Transport Stream packets and demuxes the H.264 video and AC-3 or AAC audio streams for processing.
-c:v libx264 Sets the video encoder to libx264, which produces H.264 video in the output M2TS file. Since the MTS source also typically contains H.264, this re-encodes the stream to ensure it is fully BDAV-compliant rather than simply copying the raw camcorder bitstream.
-c:a aac Encodes the audio to AAC, replacing whatever audio codec the MTS source used (commonly AC-3 or AAC from the camcorder). AAC is broadly compatible with Blu-ray software, media servers, and BDAV players, making it a safe default for M2TS output.
-crf 23 Sets the Constant Rate Factor for libx264 to 23, the standard default that balances visual quality against file size. For AVCHD camcorder footage, this typically produces output that is visually indistinguishable from the source while keeping file sizes manageable.
-b:a 128k Sets the AAC audio bitrate to 128 kilobits per second. This is sufficient for clear stereo audio from a camcorder microphone and is well within the range that Blu-ray authoring tools and BDAV players support without issue.
output.m2ts Specifies the output filename with the .m2ts extension, which signals FFmpeg to use the BDAV MPEG-2 Transport Stream muxer. This produces a properly framed M2TS file with 192-byte packets as expected by Blu-ray authoring software and BDAV-compatible players.

Common Use Cases

  • Preparing raw AVCHD camcorder footage from a Sony Handycam or Panasonic HC series for import into Blu-ray authoring software like Vegas DVD Architect or Encore, which expects BDAV-compliant M2TS files rather than raw MTS clips.
  • Archiving family events or wedding footage shot on an AVCHD camcorder into M2TS for long-term storage on a NAS or media server running Plex or Kodi, both of which index M2TS more reliably than raw MTS.
  • Preparing HD camcorder clips for a professional video editor that accepts M2TS as a native timeline format, avoiding transcoding penalties during the edit.
  • Creating BDAV-compliant M2TS streams for streaming to a Sony PlayStation or other Blu-ray-capable device over a home network using DLNA or UPnP media sharing.
  • Converting a batch of MTS clips recorded at a sports event or concert into M2TS for delivery to a post-production house whose ingest pipeline expects Blu-ray transport stream packaging.
  • Rewrapping AVCHD vacation footage into M2TS so it can be burned onto a standard Blu-ray disc using consumer burning software without the disc player rejecting the stream due to an incompatible container header.

Frequently Asked Questions

Yes, there is a small degree of quality loss because the video is re-encoded with libx264 at CRF 23, rather than simply rewrapped. Since both formats use H.264 video, a lossless remux would technically be possible, but re-encoding ensures the output is clean and spec-compliant for BDAV. At CRF 23, the quality loss is generally imperceptible on typical camcorder footage. If you want to minimize quality loss, lower the CRF value toward 18 in the FFmpeg command — each step down preserves more quality at the cost of a larger file.
AVCHD camcorders frequently record audio as Dolby AC-3 (also called Dolby Digital), which is a common codec in the MTS container. This tool re-encodes audio to AAC at 128k because AAC offers broad compatibility with media players, Blu-ray software, and DLNA servers. If you need to preserve AC-3 audio in the M2TS output, you can modify the FFmpeg command on your desktop using '-c:a copy' if the source is already AC-3, or replace 'aac' with 'ac3' and adjust the bitrate accordingly.
Both MTS and M2TS are MPEG-2 Transport Stream files carrying H.264 video, but they differ in their container framing. MTS is the raw AVCHD stream exactly as written by a camcorder to an SD card or internal flash memory. M2TS is the BDAV variant of that stream, which includes additional 4-byte Blu-ray timing headers on each transport packet, making it the correct format for Blu-ray disc structures and compatible BDAV authoring workflows. The file extension itself is often the most visible difference, but the internal packet structure is genuinely distinct.
M2TS supports multiple audio tracks, and FFmpeg will attempt to map all audio streams from the MTS source by default. However, this tool's default command re-encodes the primary audio track to AAC. If your MTS file contains multiple audio tracks — for example, a stereo mix and a separate commentary track — you should run the FFmpeg command locally with explicit '-map' flags to select and encode all desired audio streams. The browser-based tool handles standard single-track AVCHD recordings cleanly.
Video quality is controlled by the '-crf 23' flag in the command. CRF stands for Constant Rate Factor and works on a scale where lower numbers mean higher quality and larger file size, and higher numbers mean lower quality and smaller file size. For near-lossless output from your camcorder footage, try '-crf 18'. For smaller files where some quality loss is acceptable, try '-crf 28'. The audio bitrate is controlled by '-b:a 128k' — changing this to '-b:a 192k' or '-b:a 256k' will improve audio fidelity at the cost of a slightly larger file.
Yes. On Linux or macOS, you can run a simple shell loop: 'for f in *.mts; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.mts}.m2ts"; done'. On Windows Command Prompt, use: 'for %f in (*.mts) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.m2ts"'. This is particularly useful for processing a full card dump of AVCHD footage, since the browser tool handles files one at a time and is limited to 1GB per file.

Technical Notes

MTS and M2TS share the MPEG-2 Transport Stream foundation, which means this conversion is structurally closer than, say, converting between completely different container families. The key technical distinction is the BDAV 4-byte source packet header that M2TS adds to each 188-byte TS packet, bringing the packet size to 192 bytes — this is what Blu-ray authoring tools and BDAV-aware players look for. FFmpeg handles this transparently when writing to an .m2ts output. One important consideration for AVCHD workflows: the original MTS file stores clip metadata (clip information, thumbnail index, and stream attributes) in a sidecar directory structure (PRIVATE/AVCHD/BDMV), and this metadata is not carried into the M2TS file itself — it is discarded during conversion. Subtitle streams embedded in the MTS source are supported in M2TS output since both containers support subtitle tracks, but AVCHD camcorders rarely embed subtitle streams. The CRF-based encoding ensures consistent visual quality across the clip rather than a fixed bitrate, which is well-suited for the variable-complexity footage typical of camcorder recordings. Chapter markers are not supported in either format by FFmpeg's M2TS muxer, so any chapter structure from authoring software would need to be re-applied after conversion.

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