Convert WebM to MP3 or hand over the WebM and get the words.
To convert WebM to MP3, run ffmpeg -i recording.webm -vn -c:a libmp3lame -b:a 64k -ac 1 recording.mp3, or in VLC choose Media, then Convert/Save, and pick an MP3 audio profile (labels shift a little between versions). For a transcript you can usually skip the step: a WebM uploads as it is, one file can run up to 10 hours or 5 GB, and a 3-hour recording comes back in about 6 minutes.
Two commands and a menu
Most WebM files are a browser's recording of a call or a screen. The sound inside is what you need.
Audio only, with ffmpeg
The -vn flag throws the picture away and -ac 1 folds the voices to mono, so ffmpeg -i class.webm -vn -c:a libmp3lame -b:a 64k -ac 1 class.mp3 leaves a small speech file. The sound in a WebM is usually Opus, sometimes Vorbis; ffmpeg reads both. If the build complains that libmp3lame is missing, install a fuller ffmpeg package.
The VLC route
Open VLC, then Media, then Convert/Save. Add the WebM, press Convert, choose an Audio - MP3 profile and give the destination a name ending in .mp3. VLC plays the file through while it converts, so a three-hour capture takes several minutes rather than seconds. Menu names differ slightly across releases and on macOS, where the option sits under File.
A WebM that shows 0:00
Files written by a browser recorder sometimes carry no duration in the header, so players show 0:00 or refuse to seek. ffmpeg -i in.webm -c copy fixed.webm rewrites the container without re-encoding and usually puts the length back. Do that before trimming anything, because an editor may cut in the wrong place on a file with no index.
Or upload the WebM itself
The box on this page lists WebM video next to audio, so the original goes up as it is. Files over 500 MB continue on the upload page, still up to 10 hours or 5 GB. Converting never changes the running time, which means the minutes counted are the same either way.
Where WebM jobs go wrong
The trouble is rarely the conversion. It is the size of the video and the habit of converting files that never needed it.
✗ Converting out of habit
A long screen capture gets converted twice, trimmed in an editor that could not seek, and uploaded as several pieces.
- Re-encoding video nobody will watch
- Trimming a file with no duration index
- Cutting a 3-hour session into four parts
- Choosing 320 kbps for a talking voice
- Waiting on a multi-GB upload over Wi-Fi
- A YouTube download instead of its link
✓ Sound first, upload once
The voice track comes out in a minute, goes up as one small file, and the transcript keeps the original timeline.
- Try the WebM as it is first
- Audio only if the file is several GB
- 64 kbps mono: about 29 MB an hour
- Repair the header before any trim
- Paste YouTube or Vimeo links instead
- 180 minutes on the $4 pack of 300 minutes
Sample
A recorded browser workshop, two hours in, after the WebM was cut to audio.
Illustrative lines written for this page, not taken from a real session. Timestamps match the WebM, because dropping the picture does not move the sound.
Export
One transcript. Five clean formats.
Every pack exports all five — no format is held back for a higher tier.
Plain text
De-ummed paragraphs. Ready to paste.
SRT captions
Timed to the speech. Every video editor reads this.
WebVTT
HTML5 player + YouTube uploads.
Show notes
Formatted with chapters and pull-quotes.
Machine-readable
Timestamped text for your own tools.
Pricing
Honest pricing, no surprises.
A pack from $4 (300 minutes) opens the full transcript. After that, no subscription and no auto-renew — every tier is a one-time minute pack, and credits never expire. Buy once, use the minutes whenever you need them.
Casual pack
$4/300 min
5 hours of audio — $0.80 an hour. One-time — credits never expire.
- 300 minutes of audio
- All export formats
- AI chat over the whole transcript
- Executive summary & key quote
Best value
$18/3,000 min
50 hours of audio — $0.36 an hour. Credits never expire.
- 3,000 minutes of audio
- Summary, chapters and key quotes
- All export formats
- AI chat over the whole transcript
Bulk pack
$32/6,000 min
100 hours of audio — $0.32 an hour. Credits never expire.
- 6,000 minutes of audio
- Summary, chapters and key quotes
- API access for batch pipelines
- All export formats
FAQ
WebM to MP3, answered.
Do I need to convert a WebM before transcribing it?
Usually not. WebM is on the list of video types the upload takes, so try the original first. Convert to MP3 when the WebM is several gigabytes of screen video, or when another tool you use only opens MP3.
How big is the MP3 compared with the WebM?
A 64 kbps mono MP3 is about 29 MB an hour, so three hours come to roughly 86 MB. The WebM depends on resolution and how much moves on screen: a three-hour capture can be a few hundred megabytes or several gigabytes.
What happens if the WebM is over 2 GB?
Uploads go up to 5 GB with or without a pack; a bigger file needs splitting or an audio export. Pulling out the audio track is the quicker fix, since the sound alone is a small fraction of a large screen recording.
How long does a long WebM take?
About 2 minutes per audio hour once it has uploaded: three hours in roughly 6 minutes, ten hours in about 20. A file longer than 10 hours goes up as two files.
What does it cost?
Minutes of audio only. A 3-hour recording uses 180 minutes of the $4 pack of 300 minutes. Every recording starts with a free preview of its opening minutes, and unused credits stay on the account.
The WebM came from a YouTube download. Anything simpler?
Paste the YouTube link instead; links need no upload, and live replays work too. The same goes for Vimeo, Twitch and Kick recordings and Google Drive share links. Stick to recordings you own or are allowed to use.
Related
Related pages
Upload the WebM. Convert only if the upload refuses it.
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