Convert Opus to MP3 only when something else insists on MP3.
To convert Opus to MP3, run ffmpeg -i voice.opus -c:a libmp3lame -b:a 64k voice.mp3, or use VLC's Convert/Save with an MP3 profile (names vary by version). For a transcript you rarely need to: Opus is already compact, about 14 MB an hour at 32 kbps, so even a 10-hour file is around 144 MB, and it is transcribed at about 2 minutes per audio hour.
When conversion helps, and how
Opus was built for voice over the internet. Converting it to MP3 trades a smaller file for a more familiar one.
The command
ffmpeg -i voice.opus -c:a libmp3lame -b:a 64k voice.mp3 is all it takes; add -ac 1 if the recording is one voice on two channels. Opus inside .ogg, .oga or .webm converts with the same line, just a different input name. Going above the source's own bitrate only adds size.
VLC, from a menu
Media, then Convert/Save, add the file, press Convert and choose an MP3 audio profile. On macOS the same feature sits under File as Convert / Stream. VLC plays through the file as it converts, so a long recording takes a few minutes.
When MP3 is worth it
An editor, a podcast host or a colleague's player that will not open Opus. Some older phones and car stereos skip it too. If the only goal is a transcript, none of that applies.
Upload the Opus instead
Send the original through the box above; if your file picker greys out .opus, rename nothing, just convert once. Files over 500 MB, rare for Opus, continue on the upload page. Converting leaves the running time and the minutes counted unchanged.
Where Opus jobs go wrong
The most common mistake is making a small file bigger and then worrying about upload size.
✗ Converting by reflex
A five-hour Opus recording turns into a 320 kbps MP3 several times its size, and then gets split to fit.
- MP3 at 320 kbps from a 24 kbps source
- Splitting a 5-hour file that was 70 MB
- Renaming .opus to .mp3 without converting
- Converting 60 voice notes one by one
- Losing the original after conversion
- Recording a call without asking first
✓ Leave Opus as Opus
The original uploads in seconds and the transcript uses the recording's own timeline.
- Try the .opus file first
- Convert only if a picker refuses it
- 64 kbps at most if you do convert
- Join many short notes into one file
- About 10 minutes for 5 hours
- Packs from $4 for 300 minutes
Sample
A five-hour recorded planning call, saved as Opus, near the end.
Illustrative lines written for this page, not from a real call. Opus keeps the timing exactly, so the timestamps match the original file.
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
Opus to MP3, answered.
Is Opus smaller than MP3?
For speech, yes. Opus at 24 to 32 kbps sounds clear for a voice, about 11 to 14 MB an hour, while a 64 kbps MP3 is about 29 MB an hour. Converting usually makes the file larger.
Where do .opus files come from?
Messaging apps often store voice messages as Opus, sometimes in an .ogg or .oga file. Browser recorders, some call recorders and audio downloads from video sites use it too. If it came from YouTube, paste the YouTube link instead of uploading anything.
Can I transcribe many short voice notes together?
Yes, each can go up on its own and the minutes are the same. If you want one transcript, join them first with a list file and ffmpeg's concat option, then upload the joined file. Keep the order in the list the order they were sent.
How long does a long Opus recording take?
About 2 minutes per audio hour: five hours in roughly 10 minutes, ten hours in about 20. Longer than 10 hours means two files.
What does it cost?
Packs start at $4 for 300 minutes, and credits never expire. Four weekly 2.5-hour group calls, 600 minutes, fit the $18 pack of 3,000 minutes. The opening minutes are a free preview the first time, and leftover credits wait for the next recording.
Anything to check before uploading a recorded call?
Recording a call needs the consent the law where you are requires, so ask before you press record. Only convert or upload recordings you own or have the right to use. The audio stays on our own servers and is never used for training.
Related
Related pages
Upload the Opus file. It is already the small one.
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