Convert MP4 to captions

Create accessible closed captions from your MP4 videos. Meet accessibility requirements with professional captions including speaker identification.

ADA compliant
5-min turnaround
Accessible
Audio
Video
DOCX
SRT/VTT
PDF
53+ Languages
About This Format

Understanding MP4 files

What is a MP4 file?

Universal video standard for web, mobile, and streaming

An MP4 file is also known as a MPEG-4 Part 14 multimedia container. MP4 files were developed by the Moving Picture Experts Group (MPED). WIth an MP4 File, there are separate compression algorithms for the audio and video tracks. Typically, video is compressed with the MPEG-4 codec and the audio is compressed using the AAC codec (which is the same codec used in AAC files). Most MP4 files are downloaded from Apple’s iTunes STore since most of the media downloaded from the store is downloaded in this format. The MP4 format is also used for Internet streaming video.

Common Uses

  • YouTube videos
  • Social media content
  • Video streaming
  • Mobile video playback
  • Video editing

Audio Quality

Industry standard with excellent audio/video quality

Transcription Tips for MP4

  • Most common video format - excellent Sonix support
  • AAC audio track provides great transcription accuracy
  • Works with all resolution from 480p to 4K
  • Screen recordings in MP4 transcribe well

Where MP4 Files Come From

  • YouTube downloads
  • Smartphone cameras
  • Screen recorders
  • Video editors
  • Streaming services
10x
Faster than real-time
Get your MP4 captions in minutes
99%
Accuracy rate
Industry-leading AI for MP4 files
53+
Languages
Captions in any language
30+
Export formats
SRT, VTT, SCC, and more
How It Works

Create captions from MP4 in 6 steps

Step 1

Create account

Sign up for Sonix's free trial. Includes 30 minutes free.

Step 2

Upload file

Upload your MP4 file from your computer or cloud storage.

Step 3

Select language

Choose from 53+ languages spoken in your file.

Step 4

Auto-transcribe

Sonix AI transcribes your MP4 with word-level timestamps.

Step 5

Edit captions

Fine-tune timing and formatting for accessibility.

Step 6

Export

Download closed captions in SRT, VTT, or SCC format.

Common Questions

Everything about MP4 captions

What's the difference between captions and subtitles for MP4?

Captions include speaker identification and sound descriptions for deaf and hard-of-hearing viewers. Subtitles assume the viewer can hear and focus on translating dialogue.

Are MP4-to-caption conversions ADA compliant?

Sonix generates captions meeting ADA and Section 508 requirements when you include speaker labels and review for accuracy.

Can I add sound descriptions to MP4 captions?

Yes! After transcription, add non-speech descriptions like [music playing], [door closes], or [applause] in Sonix's editor for fully accessible captions.

How do I indicate speakers in MP4 captions?

Sonix automatically detects and labels different speakers. Customize names before exporting. Speaker labels appear at the start of each caption segment.

What caption format works for broadcast MP4?

For broadcast television, export to SCC or STL formats which meet FCC closed captioning requirements.

How accurate are AI-generated captions from MP4?

Sonix achieves 99%+ accuracy on clear MP4 audio. For professional captioning, a quick human review ensures perfection.

Why Sonix

Accessible captions from MP4 files

Accessibility First

Create captions that make your content accessible to deaf and hard-of-hearing viewers.

ADA Compliant

Meet accessibility requirements with properly formatted closed captions.

Sound Descriptions

Add non-speech elements like [music] and [applause] for full context.

SEO Benefits

Captions make video content searchable and improve discoverability.

Related

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Other file formats

FLV to text
MK3D to text
WMV to text
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OGV to text
QT to text
VOB to text
M2V to text
MPG to text
MOV to text
See all supported file formats
Reviews

Trusted by accessibility teams

4.98 rating from 211 reviews

The accuracy of the initial transcription was better than any I've used to date, and making adjustments was very simple.
RM
Russ M.
Edmonton, Canada
Time is money, and that is exactly what Sonix is saving. Time! So it's worth every penny!!
PW
Patrick W.
Fredericksberg, Denmark
I love, love, love this service! Sonix is amazing! I plan to use the transcripts I've gotten so far to update the content of my podcast so that it will aid in SEO on my website. Ve...
KI
Kiki I.
Washington DC, USA
Having tried numerous transcription services, this was undoubtedly the best. There were features (such as the synching up of the audio to the words for review) that I hadn’t ever h...
RD
Raeven D.
Montreal, Canada
What a great transcript experience! I love the work they are doing at Sonix. Their webpage is really simple to use and yet you get everything you need... most of t...
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Jose Rodrigo O.
Mexico City, Mexico
I love how easy it is – it saves me so much time transcribing – I can just pull out the main points of interest from the transcription.
NJ
Noreena J.
Windsor, Canada
I was amazed by your accuracy. What I used were not very good recordings. One with an American accent, another one Australian and many background noises. The transcript exc...
AZ
Andrew Z.
Hammersmith, United Kingdom
Fantastic product and service. Fast, great quality transcript, great online editing facility. Whole experience was easy and problem free.
SL
Sonia L.
Perth, Australia
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AI transcription and translation in 53+ languages.

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