How big is a 4-hour MP4? Between about 4 and 30 GB.
A 4-hour MP4 is usually between about 4 and 30 GB: roughly 4.5 GB at 720p (2.5 Mbps), 14.4 GB at 1080p (8 Mbps) and 28.8 GB at 4K (16 Mbps). Its audio at 128 kbps is only about 230 MB, so extract that and upload it, and the 4 hours transcribe in about 8 minutes with the first 20 minutes free.
4 hours, worked out
Resolution and bitrate set the size. The transcript only needs the sound.
The formula
Size is bitrate × seconds ÷ 8. Four hours is 14,400 seconds. At 2.5 Mbps that is 4.5 GB; at 8 Mbps, 14.4 GB; at 16 Mbps, 28.8 GB. A mostly still screen recording can be much smaller; a high-bitrate camera file can be larger.
The audio inside
The sound track is usually AAC at 128 to 256 kbps: 128,000 × 14,400 ÷ 8 is about 230 MB for 4 hours, and 256 kbps about 460 MB. That is the part that becomes text.
Against the 5 GB line
Only the low-bitrate 720p version of a 4-hour MP4 comes close to fitting, and it waits for a pack if it is over 2 GB. The 1080p and 4K versions are three to six times the limit, so extract the audio and upload that on the upload page.
The one-line extraction
ffmpeg -i event.mp4 -vn -c:a copy event.m4a copies the AAC track in seconds without re-encoding. VLC's Media, Convert / Save menu does the same with a few clicks, and the timestamps still match the video.
Why a 4-hour MP4 will not go up
Four hours of picture is gigabytes; four hours of speech is not.
✗ Pushing the full MP4
Even the 720p version, about 4.5 GB, is around 180 times the OpenAI Whisper API's documented 25 MB upload limit.
- A 14 GB 1080p file over the line
- Half a day of upload time
- Cutting the event into clips
- Each clip with its own clock
- Shrinking the picture to save size
- No chapters across the 4 hours
✓ Audio out, one transcript
About 230 MB goes up and the 4 hours come back as a single document.
- About 230 MB for 4 hours
- About 8 minutes to transcribe
- Timestamps match the video
- $6 for 500 minutes, 260 left
- Chapters, names and numbers
- SRT and VTT for the MP4
Sample
A 4-hour training day recorded as one MP4, hour three.
This sample is illustrative: it was written for this page and is not from a real training day. The timestamps follow the original 4-hour video.
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
4-hour MP4 files, answered.
How long does a 4-hour MP4 take to transcribe?
About 8 minutes once the audio is up. Extracting the AAC track with stream copy takes seconds; uploading 230 MB is a few minutes on most broadband.
What does 4 hours cost?
A 4-hour file counts as 240 minutes. The first 20 minutes are free, and the $6 pack (500 minutes) transcribes the rest, leaving 260 minutes. Eight 4-hour days, 1,920 minutes, fit the $12 pack of 2,000 minutes.
How do I find my MP4's bitrate?
Check the file's properties (on Windows, Properties then Details; on a Mac, Get Info or the Inspector in QuickTime) or run ffprobe event.mp4. Multiply total bitrate by 14,400 seconds and divide by 8 for bytes.
Can I upload the MP4 without extracting?
If it is under 5 GB, yes; over 2 GB it starts once a pack is on the account. Should the upload refuse the MP4, convert it to MP3 first; the words stay the same.
Does it work for a 4-hour recording in another language?
Yes. The language is detected automatically from 99, and a recording that switches between English and Tagalog is handled. Background music is not transcribed; the speech is.
Which exports, and where is the video processed?
Five exports (TXT, DOCX, SRT, VTT, JSON), and the trainer and participants are named in the summary, quotes and chapters. Video and audio are transcribed on our own servers and are never used for training.
Related
Related pages
Upload the audio from your MP4. The first 20 minutes of the 4 hours are free.
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