Extract Audio from MTS to MP3 — Free Online Tool
Extract the audio track from AVCHD camcorder footage (.mts files) and convert it to MP3 — stripping the H.264 video and re-encoding the AC-3 or AAC audio using the LAME encoder. Ideal for pulling speech, ambient sound, or event audio from Sony or Panasonic camcorder recordings.
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FFmpeg Command
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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 are AVCHD recordings packaged in an MPEG-2 Transport Stream container, typically carrying H.264 video alongside AC-3 (Dolby Digital) or AAC audio. This tool discards the video stream entirely and re-encodes the audio track to MP3 using the LAME encoder (libmp3lame). Because MTS audio is usually AC-3 or AAC — neither of which can be directly stored in an MP3 file — a full audio transcode is required rather than a simple stream copy. The result is a standalone MP3 file at 128kbps by default, decoded from the original camcorder audio and re-compressed into the universally compatible MP3 format.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser version of this tool, this runs via FFmpeg.wasm compiled to WebAssembly — no installation required and no files leave your device. |
-i input.mts
|
Specifies the input AVCHD file in MTS format. FFmpeg demuxes the MPEG-2 Transport Stream container to access the H.264 video and AC-3 or AAC audio streams inside. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the H.264 video stream from the MTS file. This is necessary because MP3 is a pure audio format and cannot contain a video stream. |
-c:a libmp3lame
|
Selects the LAME MP3 encoder to re-encode the camcorder's audio (decoded from AC-3 or AAC) into the MP3 format. LAME is the industry-standard encoder for producing MP3 files with broad device and software compatibility. |
-b:a 128k
|
Sets the MP3 output bitrate to 128 kilobits per second, the default balance between file size and audio quality. For camcorder speech recordings this is typically sufficient; increase to 192k or 320k for music or higher-fidelity audio extracted from concert or performance footage. |
output.mp3
|
The output filename for the resulting MP3 audio file. The .mp3 extension tells FFmpeg to use the MP3 muxer, producing a file playable on virtually any device, media player, or platform. |
Common Use Cases
- Extracting speech or narration from a Sony or Panasonic camcorder interview recording to use in a podcast or voiceover project
- Pulling the audio from a wedding or event MTS recording to share as a music or ambient sound file without transferring the large video
- Archiving the audio commentary from camcorder footage when storage space is limited and the video is no longer needed
- Extracting a live music or concert recording captured on an AVCHD camcorder to create an MP3 audio file for playback on any device
- Separating ambient or nature sound captured on a camcorder for use as background audio in video editing or sound design projects
- Getting the audio out of an MTS file for transcription purposes when the video content is irrelevant
Frequently Asked Questions
Yes, there will be some quality loss. MTS files from AVCHD camcorders typically store audio as AC-3 (Dolby Digital) or AAC, both of which are already lossy formats. Converting to MP3 is a second round of lossy compression, which compounds the degradation slightly. At 128kbps the result is generally acceptable for speech and casual listening, but if you need higher fidelity — for example from a concert recording — consider increasing the bitrate to 192kbps or 320kbps using the quality setting before converting.
Yes. The LAME encoder used in this conversion preserves the stereo channel layout from the source MTS file by default. AVCHD camcorders typically record in stereo (and sometimes 5.1 surround for AC-3), so if your footage has a standard stereo track, the resulting MP3 will be stereo. If the source is 5.1 surround AC-3, FFmpeg will downmix it to stereo for the MP3 output since MP3 does not natively support multichannel surround.
By default, FFmpeg selects the first audio stream in the MTS file, which is the primary audio track recorded by the camcorder's built-in or attached microphone. Some AVCHD cameras record a secondary audio track at a different level or channel configuration. If you need to extract a specific track, you can modify the FFmpeg command by adding '-map 0:a:1' (replacing '1' with the zero-indexed track number) before the output filename to target a particular audio stream.
Replace the '-b:a 128k' value in the command with your desired bitrate. For example, use '-b:a 192k' for a noticeable quality improvement or '-b:a 320k' for the highest standard MP3 bitrate. Since the source audio in an MTS file is already lossy AC-3 or AAC, increasing the bitrate beyond the original source's effective quality won't recover lost detail, but it does reduce the additional compression artifacts introduced by the MP3 re-encode.
Yes. On Linux or macOS, you can use a shell loop: 'for f in *.mts; do ffmpeg -i "$f" -vn -c:a libmp3lame -b:a 128k "${f%.mts}.mp3"; done'. On Windows Command Prompt, use: 'for %f in (*.mts) do ffmpeg -i "%f" -vn -c:a libmp3lame -b:a 128k "%~nf.mp3"'. This is especially useful for extracting audio from a full memory card of camcorder footage at once.
MTS/AVCHD files store metadata in transport stream structures rather than ID3 tags, so there is typically very little user-facing metadata (like title or artist) embedded in the original camcorder file. FFmpeg will attempt to map any available metadata to the MP3's ID3 tags, but in practice the output MP3 will usually have minimal or no metadata. You can add ID3 tags manually after conversion using a tag editor like Mp3tag or MusicBrainz Picard.
Technical Notes
AVCHD MTS files use the MPEG-2 Transport Stream container, which presents a parsing challenge for some software due to its broadcast-oriented structure. FFmpeg handles MTS demuxing reliably, but the audio codec inside the container matters: if the camcorder recorded AC-3 (common on higher-end Panasonic and Sony models), FFmpeg decodes the AC-3 frames before re-encoding to MP3 via libmp3lame. If the source audio is AAC (more common on consumer-grade AVCHD cameras), the same decode-then-encode pipeline applies. In either case, a direct stream copy to MP3 is not possible because MP3 is a raw audio format — it does not act as a container capable of holding AC-3 or AAC bitstreams. The '-vn' flag is essential here to suppress the H.264 video stream, since MP3 is audio-only and FFmpeg would otherwise error or attempt to encode video. One known limitation: some MTS files from dual-recording cameras (writing simultaneously to internal memory and SD card) may have slight audio sync offsets — these are preserved as-is in the MP3 output since no video reference remains after extraction.