Free online WEBM to MTS converter

What the WEBM format is

WEBM is an open multimedia container designed mainly for web playback. It commonly stores VP8, VP9, or AV1 video with Vorbis or Opus audio. Browsers, screen-recording applications, streaming tools, and some editors create .webm files; OBS Studio and browser-based recording tools are common sources. WEBM is efficient for online delivery, but older hardware players, editors, and authoring programs may not support its codecs.

What the MTS format is

MTS is a filename extension commonly used for MPEG-2 transport stream video from AVCHD camcorders, particularly Sony and Panasonic models. AVCHD recordings typically contain H.264/AVC video and AC-3 audio, often with 48 kHz audio and 1080i or 1080p video. The transport-stream container supports packetized media and can carry multiple streams, which suits camcorder and some broadcast-style workflows.

The .mts extension does not guarantee a complete AVCHD recording. Direct playback on a camcorder or Blu-ray device may also require the camera's folder structure, playlists, supported bitrate, frame rate, resolution, H.264 profile, and audio settings.

How to convert WEBM to MTS with FFmpeg

FFmpeg provides the most control and can perform the conversion directly. Because WEBM commonly uses VP8, VP9, AV1, Vorbis, or Opus while AVCHD-style MTS normally uses H.264 and AC-3, this is a transcoding operation, not a simple change of the filename or container.

1. Install FFmpeg from the official FFmpeg distribution or your operating system's package manager.
2. Open Command Prompt, PowerShell, or a terminal in the folder containing the source file.
3. Run this command, replacing the filenames as needed:

ffmpeg -i input.webm -map 0:v:0 -map 0:a:0? -c:v libx264 -preset medium -crf 18 -pix_fmt yuv420p -c:a ac3 -b:a 192k -ar 48000 -f mpegts output.mts

• -c:v libx264 encodes the video as H.264.
• -crf 18 targets high visual quality; values around 21–24 produce smaller files with more compression.
• -c:a ac3 -ar 48000 encodes audio as AC-3 at 48 kHz.
• -f mpegts creates an MPEG transport stream, and the .mts extension identifies the resulting file.
• The ? after the audio map lets FFmpeg continue when the WEBM contains no audio.

The command writes output.mts to the current terminal folder. It converts only the first video and first audio stream; subtitles, chapters, and some metadata are not automatically carried into the output.

Graphical and no-installation options

A desktop editor or transcoder with FFmpeg-based export can also open the WEBM and use Export or Render with MPEG transport stream or MTS as the output. Select H.264 video and AC-3 audio when the application exposes codec settings. HandBrake is useful for producing an intermediate H.264 file, but it does not normally export MTS directly, so it is less direct for this task.

You can also convert the file for free on 101convert.com without installing software. Do not upload confidential footage unless its handling policy is suitable for the material.

Quality and compatibility limits

Re-encoding cannot restore detail lost in the original WEBM. Keep the source file as an archive and avoid repeated conversions. The MTS file may be larger because H.264 and AC-3 settings suitable for camcorder workflows can use more data than web-oriented WEBM encoding.

A generic MPEG transport stream named output.mts may work in a media player or editor but fail in a camcorder or Blu-ray device that expects a complete AVCHD directory structure. For hardware playback, check the device specification for resolution, frame rate, interlacing, H.264 profile and level, maximum bitrate, audio format, and required folder layout. A successful conversion therefore confirms container compatibility, not universal AVCHD-device compatibility.