About these tools
Every tool on this page runs ffmpeg, the open-source media engine, inside your browser tab, so the file stays on your computer or phone. They are useful on their own, and they also get awkward files ready for mydubly: a WhatsApp voice note or a call recording can become an MP3 you can transcribe or translate.
Which tool do you need?
To keep only the sound of a video, use a video-to-audio converter: MP3 for a file that plays anywhere, WAV for editing, or M4A to keep the original AAC sound without re-encoding. To change one audio format into another, such as a voice note, a call recording or a lossless music file, use the audio converters. When a video won't play or upload because it is MOV, MKV or WebM, the MP4 converters rewrap or re-encode it. To make a recording smaller or shorter, use the compressor or the cutter, and check your microphone before recording with the mic test.
Speed and limits
Most conversions finish in seconds. Saving sound from a video, rewrapping MOV or MKV as MP4, and converting between audio formats are fast because the browser reads only what it needs. Re-encoding video, which WebM to MP4 requires, is much slower in a browser than in a desktop app. The first conversion downloads the engine, about 30 MB, which is then cached. Results are built in memory, so outputs larger than about 1.5 GB are refused, and the tab has to stay open until the download is ready.
Video to audio
Save the soundtrack of a video as an audio file. When the sound is already AAC it can be copied out without re-encoding.
Audio converters
Change an audio file's format: phone recordings, voice notes, lossless masters and everything in between.
Video converters
Put a video into an MP4 that plays almost everywhere, copying the picture whenever the codec allows.
Trim, shrink and test
Cut a recording down, make it smaller, or check your microphone before you record.
Frequently asked questions
Are these tools really free?
Yes. They need no account, add no watermark and have no daily limit, because the work happens on your own device rather than on a server.
Are my files uploaded?
No. The file is read by your browser and converted there. mydubly never receives it unless you separately choose to upload it for transcription or translation.
Do the tools work on a phone?
Yes, in a current mobile browser. Phones are slower than laptops, so long files and video re-encoding take longer.