Inspect first, keep the source untouched
A read-only check is the lightest operation. It helps you decide whether the source already meets a destination’s measurable limits before considering a trim, container change, or re-encode.
Local video inspector
See the video facts before you change anything.
Choose one common video file to read browser-observable duration, display dimensions, bytes, container hint, and local playback support. Inspection does not create a copy.
Your video stays on this device. No upload, account, or server-side processing job.
Browser-local workspace
Choose a local video to begin.
Choose one local MP4, M4V, MOV, or WebM file. JavaScript activates a browser-native preview and capability check; available conversions depend on the codecs supported by this device.
No upload, account, or server-side media job.
The local workspace loads after you choose a video.
Codec detail comes from the local parser
Native browser metadata exposes duration and display size, while the local worker adds available codec, audio-track, sampled frame-rate, and rotation facts without sending the file away.
Private browser processing
Your video remains in your hands.
Aftermath reads selected video bytes only in the current browser. Unsupported codecs are reported clearly rather than sent to another service. High-resolution conversion can use substantial device battery and processing.
What this tool checks
Inspect one local MP4, M4V, MOV, or WebM video before changing it. The read-only report can show bytes, container, duration, display dimensions, playback status, codecs, audio layout, frame rate, bitrate, and rotation when the browser and parser expose them. It creates no download and keeps the source local. A missing preview or field is reported as a capability limit, not repaired through upload. Read-only inspection accepts sources up to 4 GB.
What to choose and what you get
What to choose
- one selected local MP4, M4V, MOV, or WebM file
Result
- a local video report with bytes, duration, dimensions, tracks, and browser support facts
Supported use
- Read-only inspection of one common local video container without creating an output file.
- Browser-observable preview, bytes, duration, and dimensions plus parser-observable track and codec facts when readable.
- A compatibility-oriented starting point before choosing a separate conversion, compression, trim, crop, or extraction route.
Before you start
- File repair, transcoding, metadata editing, destination approval, or validation of facts the local parser cannot expose.
- A conclusion that preview failure proves corruption or that another browser and device will behave identically.
Supported formats
- Accepted formats: MP4, M4V, MOV, WebM.
- Output formats: HTML report.
Browser support and permissions
- Modern browser with JavaScript and support for the selected media container and codec; memory and performance vary by device. This read-only route accepts sources up to 4 GB and does not create an output file.
- No camera, microphone, or screen permission is needed.
Choose the right settings
- Use this route when the goal is to understand a source without writing a new file.
- Move to /video/convert-to-mp4, /video/compress, /video/trim, /video/crop, or /video/mp4-to-mp3 only after choosing a change.
- Use /video when you need category-level comparison rather than a read-only scan.
- Treat unavailable facts as browser-local unknowns rather than inferred defects.
Worked example
An MP4 plays inconsistently and needs its container, tracks, dimensions, duration, rotation and browser support inspected first.
Starting facts
- No replacement file should be created.
- Container extension alone does not identify every codec.
Observed operation: Read supported media metadata and track facts locally, then report playback and codec observations from this browser.
Review the result: Use the report to choose conversion, compression, crop or a specialist desktop workflow while retaining the source.
Boundary: Inspection reflects this browser and cannot prove universal decoding, stream integrity, rights or destination compatibility.
What you can do
Inspect one local video’s container, tracks, dimensions, duration, frame timing, rotation, and playback support without creating output
Choose another tool when
- This read-only route does not compress, convert, trim, crop, extract audio, or write a replacement file.
- Reported browser facts are not a certification that another platform will accept the video.
- A failed native preview does not imply that the file is corrupt or universally unsupported.
If it does not work
- An unsupported or malformed container may expose only basic file facts or no readable tracks.
- Native preview can fail even when the local parser reports some technical metadata.
- Codec, frame-rate, rotation, or duration fields remain unavailable when the selected file does not expose them to the current browser.
Things to know
- Codec support, performance, and memory use vary by browser, device, source, and operation.
Privacy boundary
The selected video stays in the current browser session and is not sent to an Aftermath processing service. How local processing is verified.
What this tool verifies
Checks the displayed limits and reports or creates a local video report with bytes, duration, dimensions, tracks, and browser support facts from one selected local MP4, M4V, MOV, or WebM file.
Check before sharing
This read-only route does not compress, convert, trim, crop, extract audio, or write a replacement file.