Convert MP4 to JSON Online Free

Extract the technical metadata of any MP4 video as structured JSON — container info, video/audio codecs, bitrate, duration, resolution, and per-stream details. Powered by ffprobe.

By ChangeThisFile Team · Last updated: March 2026

Quick Answer

ChangeThisFile extracts the technical metadata from your MP4 file as structured JSON using ffprobe on a secure server. The output includes container format, video and audio codec details, bitrate, duration, resolution, frame rate, and per-stream information. Files are auto-deleted after conversion. Free, no signup required.

Free No signup required Encrypted transfer · Auto-deleted Under 2 minutes Updated May 2026

Convert MP4 to JSON

Drop your MP4 file here to convert it instantly

Drag & drop your .mp4 file here, or click to browse

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MP4 vs JSON: Format Comparison

Key differences between the two formats

Feature	MP4	JSON
Type	Binary video container	Plain-text structured data
Purpose	Holds compressed video and audio streams	Describes data hierarchies as key/value pairs
Human-readable	No — binary payload	Yes — any text editor opens it
Contains	H.264/H.265 video, AAC/MP3 audio, subtitles, chapters	Strings, numbers, arrays, nested objects
File size	Tens of MB to many GB	Typically a few KB of metadata
Use case	Video playback and distribution	Programmatic inspection and indexing
Compatible with	Video players, browsers, editors	Every modern programming language

When to Convert

Common scenarios where this conversion is useful

Pre-flight checks before video uploads

Verify that an MP4 meets a target platform's spec — codec, bitrate, resolution, frame rate — before uploading to YouTube, Vimeo, or a social network that rejects non-conforming files.

Build a media library index

Extract metadata from a batch of MP4 files to populate a database or spreadsheet with duration, resolution, codec, and bitrate fields for searchable archives.

Debug playback or encoding issues

Inspect the exact codec parameters and stream layout of an MP4 to diagnose why a player refuses it or why a CDN rejects the encode.

Document recordings for compliance

Capture the technical fingerprint of a video — duration, frame rate, audio sample rate — as JSON evidence for legal, broadcast, or archival workflows.

Feed metadata into automation pipelines

Pipe MP4 metadata into a CI workflow, transcoding queue, or content management system using the JSON output as a typed source of truth.

Who Uses This Conversion

Tailored guidance for different workflows

For Developers

Validate user-uploaded MP4 files server-side before transcoding by checking the JSON metadata for codec and bitrate compliance
Build a media catalogue API that returns ffprobe-style JSON for any uploaded video
Write integration tests that assert codec, frame rate, and resolution after a transcode pipeline runs

Cache the JSON output keyed by file hash — metadata never changes for the same byte stream

Treat the streams array as ordered; the first video stream is typically the primary track but always check codec_type

For Video Editors

Confirm the exact codec, frame rate, and audio sample rate of a delivered MP4 before importing into a non-linear editor
Diagnose why an MP4 plays in one tool but not another by comparing the JSON-reported codec parameters

Pay attention to color_range, pix_fmt, and codec_tag_string fields — these often explain mysterious playback or compatibility issues

Cross-reference the duration and overall bitrate to estimate quality versus file size before re-encoding

For Archivists

Generate JSON metadata sidecars for every MP4 in a long-term archive so the technical fingerprint survives even if the original tooling becomes obsolete
Audit a collection of MP4 files for inconsistent encoding before migrating to a preservation format like FFV1 or ProRes

Store the JSON alongside the MP4 with the same base filename — it serves as a self-describing record for future curators

Capture the ffprobe version in your archival metadata so future readers know exactly which tool produced the JSON

How to Convert MP4 to JSON

1

Upload your MP4 file

Drag and drop your .mp4 file onto the converter, or click to browse. Files up to 500MB are supported.
2

Server-side metadata extraction

Your file is uploaded over an encrypted connection and inspected with ffprobe. Container format, video and audio streams, bitrate, duration, and frame rate are serialised as JSON.
3

Download the JSON

Click Download to save the resulting .json file. Your original MP4 is automatically deleted from our servers after processing.

Frequently Asked Questions

Does this extract the actual video frames as JSON?

No. Video pixel data cannot be meaningfully represented as JSON. This tool extracts metadata — codec, bitrate, duration, resolution, stream count, frame rate, and container info. If you need the audio track, use the MP4 to MP3 or MP4 to WAV converter instead.

What fields are included in the JSON output?

The output includes container format (e.g. mov,mp4,m4a,3gp,3g2,mj2), duration, overall bitrate, and one entry per stream with codec_name, codec_type, width, height, sample_rate, channels, frame_rate, and language tags where present.

Is the MP4 to JSON conversion free?

Yes. ChangeThisFile is free with no signup, no watermark, and no limits on how often you can run the conversion.

Are my files kept private?

Yes. Your MP4 is transferred over HTTPS and automatically deleted from our servers immediately after the JSON is generated. We do not store or access your video.

Can I parse the JSON in JavaScript or Python?

Yes. The output is standard JSON, so you can JSON.parse() it in JavaScript or json.load() it in Python. The schema matches ffprobe's -show_format -show_streams JSON format.

Will the JSON include chapter or subtitle data?

If your MP4 contains chapters, subtitle tracks, or attached metadata, those streams will appear in the JSON output. Each is listed with its codec_type (e.g. subtitle) and any associated language tags.

Does this work for very large MP4 files?

Yes. ffprobe reads only the header and stream index, so even multi-gigabyte files are processed in seconds. Files up to 500MB can be uploaded directly through the web interface.

What if my file is not a valid MP4?

If ffprobe cannot recognise the container, the converter will return an error rather than partial metadata. Try the original recording or a re-muxed copy. The tool also accepts MOV, M4V, and 3GP files since they share the same container family.

Can I use this on mobile?

Yes. The converter works in any modern mobile browser. Upload an MP4 from your camera roll and download the JSON metadata directly to your device.

Is the output the same as running ffprobe locally?

Yes. The server runs the same ffprobe binary you would run locally and returns the exact same JSON structure — no proprietary fields are added or removed.

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Need to convert programmatically?

Use the ChangeThisFile API to convert MP4 to JSON in your app. No rate limits, up to 500MB files, simple REST endpoint.

View API Docs

Read our guides on file formats and conversion

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