MyMediaTools

Convert MKV to MTS — Free Online Tool

Convert MKV files to MTS (AVCHD) format using H.264 video and AAC audio — the native encoding standard for Sony and Panasonic camcorders. This tool re-encodes your MKV content into an MPEG-2 Transport Stream container, making footage compatible with AVCHD-aware editing software and archival workflows.

FFmpeg Command

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Estimated output:

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How It Works

MKV and MTS both support H.264 video, but because MKV's H.264 stream is wrapped in a Matroska container while MTS requires an MPEG-2 Transport Stream (M2TS) structure, a full re-encode is performed rather than a simple remux. The video is re-encoded using libx264 at CRF 23, and the audio — whether it was originally AAC, Opus, FLAC, Vorbis, or MP3 inside the MKV — is transcoded to AAC at 128k to match AVCHD audio expectations. Subtitles and chapter markers from the MKV are not carried over, as the MTS/AVCHD container does not support those structures. Multiple audio tracks, if present in the source MKV, are also collapsed to a single output stream.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary — in this tool, it runs entirely inside your browser via FFmpeg.wasm (WebAssembly), so no file is sent to any server. The same binary name is used when running the command locally on your desktop.
-i input.mkv Specifies the input Matroska file. FFmpeg reads all streams from the MKV container — video, audio, subtitles, chapters, and metadata — and makes them available for processing and output mapping.
-c:v libx264 Re-encodes the video stream using the libx264 H.264 encoder, which is required because the source MKV video stream cannot be directly copied into the MTS container without re-wrapping in the correct transport stream packetization format.
-c:a aac Transcodes the audio to AAC using FFmpeg's native AAC encoder — necessary because the MKV source may contain Opus, Vorbis, FLAC, or MP3 audio, none of which are valid in an AVCHD-compliant MTS file. AAC is the standard audio codec for AVCHD alongside AC-3.
-crf 23 Sets the Constant Rate Factor for libx264 to 23, which is the default perceptually transparent quality level for H.264. Lower values (e.g., 18) produce higher quality and larger files; higher values (e.g., 28) reduce file size with more compression artifacts.
-b:a 128k Sets the AAC audio output bitrate to 128 kilobits per second — a standard stereo quality level suitable for most speech and music. If the source MKV contained high-quality or lossless audio, increasing this to 192k or 256k will better preserve fidelity in the MTS output.
output.mts Defines the output filename and triggers FFmpeg to use the MPEG-2 Transport Stream muxer based on the .mts file extension, packaging the re-encoded H.264 video and AAC audio into an AVCHD-compatible container.

Common Use Cases

  • Importing screen recordings or downloaded MKV content into Sony Vegas Pro or Cyberlink PowerDirector, which expect AVCHD/MTS as a native acquisition format
  • Preparing MKV footage for ingestion into an AVCHD folder structure on a Sony or Panasonic camcorder's SD card for playback on a connected BRAVIA TV
  • Archiving converted footage alongside genuine camcorder MTS clips so that an editing project maintains a consistent container and codec format across all media
  • Re-encoding an MKV with a VP9, HEVC, or lossless PNG video track into H.264/MTS so legacy broadcast or production equipment that only reads AVCHD streams can process the file
  • Delivering H.264 video in a transport stream container for integration into IPTV or broadcast playout systems that expect MPEG-TS encapsulation
  • Converting MKV files containing multiple audio tracks or subtitles into a clean, single-stream MTS file for simplified compatibility with consumer playback devices

Frequently Asked Questions

Yes, some generation loss is expected because this conversion requires a full re-encode — the video stream cannot be copied directly from the Matroska container into MTS without transcoding. The default CRF 23 setting produces visually transparent quality for most content at typical resolutions, but it is not mathematically lossless. If your source MKV already used H.264 at a high bitrate, encoding again at CRF 23 will introduce minor additional compression artifacts. Using a lower CRF value (e.g., 18) preserves more detail at the cost of a larger output file.
The MTS/AVCHD container format is based on MPEG-2 Transport Stream, which does not have a native mechanism for storing chapter markers or text-based subtitle tracks in the way Matroska does. During conversion, those elements are silently dropped. If subtitle accessibility is important, you should burn the subtitles into the video stream before converting, or keep the original MKV as your archival copy.
Both FLAC and Vorbis are unsupported in MTS containers, so the audio is fully transcoded to AAC at 128k regardless of the original format. FLAC in particular is lossless, so transcoding it to 128k AAC will reduce audio fidelity. If audio quality is a priority, consider raising the audio bitrate in the FFmpeg command to 192k or 256k using the -b:a flag.
Generally yes — both applications recognize MPEG-2 Transport Stream files with H.264 video and AAC audio, which is exactly what this conversion produces. However, genuine AVCHD media also includes a specific folder structure (AVCHD/BDMV/STREAM/) and metadata files that this tool does not generate. If your editing software strictly validates the AVCHD directory structure rather than accepting bare MTS files, you may need to manually place the output into that folder hierarchy.
To improve video quality, lower the CRF value — for example, replace '-crf 23' with '-crf 18' for higher fidelity at the expense of a larger file. To raise audio bitrate, change '-b:a 128k' to '-b:a 192k' or '-b:a 256k'. The full command would look like: ffmpeg -i input.mkv -c:v libx264 -c:a aac -crf 18 -b:a 192k output.mts. These same adjustments work identically whether you run the command locally or use the in-browser tool.
The displayed command processes one file at a time, but you can wrap it in a shell loop for batch processing. On Linux or macOS, use: for f in *.mkv; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.mkv}.mts"; done. On Windows (Command Prompt), use: for %f in (*.mkv) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.mts". The in-browser tool handles one file at a time, so local FFmpeg is the practical choice for batch jobs.

Technical Notes

MTS files are fundamentally MPEG-2 Transport Stream containers, a format designed for robust streaming and broadcast transmission where packet loss tolerance matters — hence its continued use in camcorder recording to flash storage. Unlike MKV, which is highly flexible and container-agnostic, MTS has a rigid structure: it expects H.264 (or H.265) video and AC-3 or AAC audio, and it does not support lossless audio codecs, text subtitles, or chapter navigation. This means any MKV containing VP9, PNG, or MJPEG video, or lossless FLAC audio, will be fully re-encoded rather than remuxed. The output file size will depend heavily on CRF value and source content complexity — at CRF 23 with 128k AAC, a typical 1080p MKV will produce an MTS of comparable or slightly larger size than an equivalent MP4, because the MPEG-TS container has higher per-packet overhead than MP4's fragmented structure. Metadata fields like title and artist tags from the MKV are not reliably preserved in MTS, and multiple audio tracks in the source will not automatically map to the output without explicit stream mapping flags added to the command.

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