Transcribe a long BWF file straight from the field recorder.
A BWF (Broadcast Wave) file at 48 kHz 16-bit stereo takes about 691 MB per hour, so the 5 GB per-file limit falls near 7.2 hours, and it transcribes at about 2 minutes per audio hour. The first 20 minutes are free, and a 3-hour field interview of 180 minutes fits on the $6 pack of 500 minutes.
Broadcast Wave, worked out
A field recorder's BWF is a WAV with a label attached. The size is what matters here.
What makes it a BWF
Broadcast Wave is a WAV file with an extra block of metadata: a description, the originator, the date and time of recording, and a time reference. Field recorders and radio systems write it by default, usually with a .wav extension, so many people have BWF files without knowing it.
The size per hour, worked
48,000 samples a second times 16 bits times 2 channels is 1,536,000 bits a second, or 192 KB. Over 3,600 seconds that is about 691 MB an hour. A mono interview track is half, about 346 MB, and 24-bit stereo is about 1,037 MB.
Where the lines fall
At 16-bit stereo, 2 GB arrives near 2.9 hours and 5 GB near 7.2, before the 10-hour line. A 10-hour mono take at 16-bit is about 3.5 GB and goes in whole. If the upload refuses the file, convert it to MP3 first; a large one continues on the upload page.
Timestamps count from the file's first second
Every time in the transcript is measured from the opening of the file, not from the recorder's time-of-day stamp. If you need clock time for a log, add the start time from the file's metadata to any timestamp.
Why long BWF files are awkward elsewhere
A morning of field audio is a gigabyte or more of WAV.
✗ Logging by ear
An hour of 16-bit stereo BWF is about 28 times the OpenAI Whisper API's documented 25 MB upload limit.
- Hours of tape logged by hand
- Uploads refused at a few hundred MB
- Takes cut into chunks to fit
- Timestamps restarting per chunk
- No list of names and places said
- No summary to pitch the story from
✓ The take, as text
The BWF goes up whole and comes back with a brief, chapters and a full transcript.
- Around 2 minutes of processing per hour
- Up to 5 GB or 10 hours per BWF
- Each interviewee named in the summary
- Names, places and dates pulled out
- SRT and VTT for the editing timeline
- Thirty hours of tape on the $12 pack
Sample
A field interview for a radio documentary.
This sample is illustrative and was written for this page; it is not from a real programme or person. Times count from the start of the BWF 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 $6 (500 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
$6/500 min
8 hours of audio — $0.72 an hour. One-time — credits never expire.
- 500 minutes of audio
- All export formats
- Unlimited AI chat per transcript
- Executive summary & key quote
Best value
$12/2,000 min
33 hours of audio — $0.36 an hour. Credits never expire.
- 2,000 minutes of audio
- Priority queue
- All export formats
- Unlimited AI chat per transcript
Bulk pack
$24/5,000 min
83 hours of audio — $0.29 an hour. Credits never expire.
- 5,000 minutes of audio
- Priority queue
- API access for batch pipelines
- All export formats
FAQ
Long BWF files, the common questions.
How long does a BWF take to transcribe?
About 2 minutes per hour of audio after upload, so a 3-hour interview takes about 6 minutes. On a slow connection the upload of a large BWF takes the longest.
What does a field recording project cost?
A 3-hour interview is 180 minutes on the $6 pack of 500. Thirty hours of field tape is 1,800 minutes on the $12 pack of 2,000, and sixty hours is 3,600 minutes on the $24 pack of 5,000. New visitors pay nothing for their first 20 minutes.
How big is a BWF per hour?
About 691 MB at 48 kHz 16-bit stereo, 346 MB mono, and 1,037 MB at 24-bit stereo. One file can be up to 5 GB, and 2 GB before your first pack.
Should I split a long BWF?
Only if it runs past 10 hours, or past 5 GB and you would rather not convert it. Otherwise upload it whole so the transcript keeps one set of timestamps.
Which languages can be in the recording?
99, detected automatically, including Afrikaans, Zulu, Hebrew and Tagalog, and a recording that switches language is handled on its main one. Ambient sound and music are not transcribed; the speech is.
Which exports, and where does the file go?
TXT and DOCX for the script, SRT and VTT for the edit, JSON for anything else. BWF recordings are transcribed on our own servers and are never used for training.
Related
Other long formats
Upload the BWF. Field tape back as text in minutes.
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