Convert MTS to WEBA — Free Online Tool
Extract and convert the audio track from AVCHD camcorder footage (MTS) into a compact WEBA file using the Opus codec — ideal for isolating speech, ambient sound, or music from high-definition video recordings. The conversion strips the H.264 video stream entirely and re-encodes the AC-3 or AAC audio to Opus inside a WebM audio container, producing a small, web-ready audio file.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
MTS files from Sony and Panasonic camcorders use the MPEG-2 Transport Stream container, carrying H.264 video alongside AC-3 or AAC audio. Converting to WEBA means the video stream is completely discarded — it is not re-encoded, just dropped — while the audio stream is decoded from its original AC-3 or AAC encoding and then re-encoded as Opus inside a WebM audio container. Opus is a modern, highly efficient lossy codec that typically achieves better audio quality than AAC at equivalent bitrates, particularly at lower bitrates like 64–128k. Because this is a full transcode of the audio (not a copy), some quality is lost in the re-encoding step, but the resulting WEBA file will be dramatically smaller than the original MTS footage.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — in this browser-based tool, it runs as a WebAssembly (FFmpeg.wasm) module entirely within your browser, with no server upload required. |
-i input.mts
|
Specifies the input AVCHD camcorder file in MTS format — an MPEG-2 Transport Stream containing H.264 video and typically AC-3 or AAC audio recorded by a Sony or Panasonic camcorder. |
-c:a libopus
|
Selects the Opus encoder for the output audio stream. Since WEBA requires Opus or Vorbis, and the MTS source contains AC-3 or AAC audio, a full re-encode to Opus is performed — there is no compatible codec to copy directly. |
-b:a 128k
|
Sets the Opus audio bitrate to 128 kilobits per second, which provides good quality for both speech and music from camcorder recordings while keeping the WEBA file compact. Increase to 192k or 256k for higher fidelity audio. |
-vn
|
Disables video output entirely, dropping the H.264 video stream from the MTS source. This flag is essential because WEBA is an audio-only container and cannot hold any video data — omitting it would cause FFmpeg to error. |
output.weba
|
Defines the output filename with the .weba extension, which signals FFmpeg to use the WebM audio container. The combination of the WebM container with Opus audio and no video stream is what defines a valid WEBA file for web playback. |
Common Use Cases
- Extract spoken commentary or interview audio from camcorder footage to use as a podcast episode or voiceover track in a web project
- Pull ambient or environmental audio from a nature or travel recording for use as a background sound loop on a website
- Archive just the audio portion of a ceremony or event recording (wedding speech, graduation address) to save storage space after video editing is complete
- Prepare audio from camcorder footage for web embedding using the HTML5 <audio> element, where WEBA/Opus offers better browser compression support than MP3
- Extract a musical performance recorded on a camcorder to share as a lightweight audio file without distributing the full video
- Isolate the audio from a field recording or documentary shoot for review, transcription, or use in audio post-production
Frequently Asked Questions
The conversion extracts whichever audio track FFmpeg selects by default — typically the first audio stream in the MTS file. Most consumer AVCHD camcorders record a single stereo or 5.1 surround AC-3 or AAC track, so in practice you will get the full audio. However, if your MTS file contains multiple audio streams (such as a separate headphone mic channel), only the default stream is included in the WEBA output. You can specify a particular stream using '-map 0:a:1' and similar flags when running the command locally.
Yes, this is a lossy-to-lossy transcode, which means the audio is decoded and then re-encoded, introducing a second generation of compression artifacts. At the default 128k bitrate, Opus performs very well and the quality loss compared to the original AC-3 or AAC track is usually imperceptible for speech and most music. However, if your original MTS audio was already heavily compressed (e.g., recorded at a low bitrate by the camcorder), the artifacts may accumulate. For critical audio work, consider increasing the bitrate to 192k or 256k using the '-b:a' flag.
The dramatic size reduction comes from two factors: the H.264 video stream — which typically accounts for 85–95% of an MTS file's size — is completely removed, and the Opus audio codec is highly efficient at the 128k default bitrate. A one-hour MTS camcorder recording might be 8–12GB, while the resulting WEBA audio file could be as small as 50–60MB. This makes WEBA an excellent format for distributing or archiving just the audio content of long recordings.
WEBA is an audio-only WebM container and is natively supported in Chrome, Firefox, Edge, and Opera. Safari added WebM/Opus support starting with Safari 15 on macOS Monterey and iOS 15, so older Apple devices or browsers may not play WEBA files without a third-party app. For maximum compatibility across all platforms including older iOS and macOS, consider converting to MP3 or M4A instead. Desktop media players like VLC handle WEBA without issues.
Replace the '128k' value in the '-b:a 128k' flag with your desired bitrate. Opus supports bitrates from as low as 6k (voice-only, very compressed) up to 320k (near-transparent quality). For speech recordings from a camcorder interview, 64k is often sufficient. For music or high-quality ambient audio, 192k or 256k will preserve more detail. For example: 'ffmpeg -i input.mts -c:a libopus -b:a 192k -vn output.weba'.
Yes. In a Unix/macOS terminal you can run: 'for f in *.mts; do ffmpeg -i "$f" -c:a libopus -b:a 128k -vn "${f%.mts}.weba"; done'. On Windows Command Prompt, use: 'for %f in (*.mts) do ffmpeg -i "%f" -c:a libopus -b:a 128k -vn "%~nf.weba"'. This is particularly useful when offloading an SD card full of AVCHD clips and you want to extract audio from all of them at once.
Technical Notes
MTS (AVCHD) files are structured as MPEG-2 Transport Streams, which include PAT/PMT program tables and packetized elementary streams — a broadcast-oriented container design not optimized for random access or web delivery. The audio in AVCHD is most commonly AC-3 (Dolby Digital) at 48kHz in stereo or 5.1 configurations, though some camcorders use AAC-LC. Neither AC-3 nor AAC is natively supported in the WebM/WEBA container, so a full audio transcode to Opus is mandatory — there is no lossless passthrough option here. Opus operates internally at 48kHz, which aligns well with the 48kHz sample rate common in camcorder recordings, avoiding any sample rate conversion artifacts. The '-vn' flag is required to suppress the video stream; without it, FFmpeg would attempt to include video in the output and fail because WEBA has no video codec support. Metadata such as recording date, GPS coordinates, and camcorder model stored in the MTS container's metadata will not be transferred to the WEBA output, as the WebM audio container has limited metadata support compared to the AVCHD specification. Chapter markers are not supported in either format for this conversion path.