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

3GP to text
RM to text
WEBM to text
QT to text
TS to text
OGV to text
MXF to text
M4V to text
M2V to text
FLV to text
See all supported file formats
Reviews

Trusted by accessibility teams

4.98 rating from 211 reviews

Your product is amazing and transcribed my files almost all accurately!
OD
Oron D.
Ramat Gan, Israel
I am VERY happy with the transcription! There were a few glitches, but 98% great.
JC
Jonathan C.
Rice Lake, WI, USA
I have tested your product among others, and I have to say, Sonix provides the best results, a really great product!!!
DB
Dan B.
London, Ontario, Canada
The fact that your service can export text as subtitles and can match the subtitles to the paragraphs in the transcript is just great! Also, the text editor is just awesome. The fa...
ED
Eugene D.
Minsk, Belarus
Found you through Google. Super easy to use. Transcribed 98% correctly even though it was not a great audio file.
RA
Rana A.
Ann Arbor, MI USA
EASY AND QUICK, VERY VERY ACCURATE!!
ST
Steve T.
Baltimore, MD USA
The best thing ever, nothing more to say.
RG
Rasool G.
Tehran, Iran
Sonix is light years ahead of all the other solutions I researched and tried!
GB
Garth B.
Calgary, Canada
Read more testimonials
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Create MP4 captions now

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