Video and audio metadata
Video and audio files can reveal device, time, software, project data, voice, and background clues.
Risks of video and audio metadata
Video and audio are difficult formats for anonymity.
Inside the file, recording date and time, device information, location information, editing software, and tag information may remain. In addition, the video or audio content itself contains clues such as faces, voices, backgrounds, notifications, environmental sounds, conversations, and locations.
They contain more information than images, and identity or routine places may be inferred from just a few seconds of video or audio.
This article organizes the information that remains in video and audio files and the points to check before publication.
Information remaining in video
Video files have both metadata and video content.
| Information | What it shows | Notes |
|---|---|---|
| Shooting date and time | When it was recorded | Connects to activity time or on-site participation |
| Location information | Shooting location | GPS may remain |
| Device information | Model or app used | Becomes a clue about the recording environment |
| Editing software | Work environment | Editor or production environment becomes visible |
| Video content | Faces, background, signs | Not erased by metadata removal |
In video, even information visible in only one frame can become a clue.
Momentary notifications and reflections also need checking.
Information remaining in audio
Audio files may retain tag information and information about the recording environment.
The audio itself is also a strong clue. Voice, way of speaking, dialect, background sound, station announcements, workplace sounds, family voices, and notification sounds may be included.
| Information | What it shows | Notes |
|---|---|---|
| ID3 tags | Title, creator, comment | May remain even in non-music recordings |
| Recording time | Time recorded | Connects to activity time |
| Recording app | Usage environment | Clue about device or work environment |
| Person's voice | Identity | Strong clue for acquaintances |
| Background sound | Place and situation | Station, shop, workplace, or home becomes visible |
Audio can reveal identity even without showing a face.
For high-risk communication, think carefully about publishing audio itself.
Metadata removal alone is not enough
For video and audio, the content remains even if metadata is removed.
| Target | Information remaining in content | Example |
|---|---|---|
| Video | Background, face, text, reflection | Signs, name badges, notifications |
| Audio | Voice, environmental sound, conversation | Station announcements, family voices |
| Screen recording | Tabs, notifications, account names | Real-name email, calendar |
| Subtitles | Names, times, places | Includes errors in auto-generated subtitles |
| Editing | Forgotten cuts, margins before and after | Conversations before and after recording |
For anonymity, check file-internal information and content separately.
Pre-publication check
Before publishing video or audio, the basic rule is not to release the original file directly.
| Check item | Reason |
|---|---|
| Create a publication copy | Protect the original file |
| Check metadata | See shooting time and device information |
| Play the entire file and check | Find momentary leaks |
| Check audio separately | Listen for background sounds and conversations |
| Look at subtitles and automatic transcription | Check whether names or places appear |
| Check filename | Avoid real names and case names |
Even in short videos, unnecessary information may appear at the beginning or end.
Recheck after cutting as well.
The decision not to publish is also necessary
Video and audio can be difficult to make completely safe even after processing.
Even if you change a voice, manner of speaking and background sound remain. Even if you hide a face, clothing and location remain. Even if metadata is removed, on-screen notifications and conversations remain. In such cases, not publishing is the safest choice.
| Situation | Reason not to publish | Alternative |
|---|---|---|
| Voice of the person or people involved is included | Acquaintances can recognize it | Transcribe and organize the content |
| Location appears strongly | Identified from background | Explain without location information |
| Minors or family members appear | Involves people other than yourself | Do not use images or audio |
| Workplace sounds or internal conversations are included | Organization or people involved become visible | Limit to a trusted consultation destination |
| Processing breaks the meaning | Causes misunderstanding or evidence problems | Store original and create separate publication material |
For anonymity, not only the technique for releasing, but also the decision not to release is important.
For high-risk material, consider giving it to a trusted consultation destination through a safe route rather than posting it publicly.
What tools can and cannot check
ExifTool and ffmpeg-related tools may be used to check video and audio metadata.
ExifTool is a representative tool that can check metadata across multiple formats.
URL : https://exiftool.org/
| Easy for tools to see | Things to check separately |
|---|---|
| Shooting date and time | Clocks and notifications in the video |
| Device information | Faces, clothing, background |
| Location information | Signs and station sounds |
| Editing software | Conversations and voice characteristics |
| Tag information | Subtitles and transcription content |
Tools help check internal information.
However, you need to check the audio and video content yourself.
Longer files are harder to check
Video and audio become harder to check as they get longer.
Even in a 10-minute video, a notification may appear for only one second. Even in 30 minutes of audio, a family voice or station announcement may appear in the middle. For anonymity, it is important not to publish without checking the whole file.
| Problem | What happens |
|---|---|
| Forgotten cuts at beginning or end | Conversations before or after recording remain |
| Notification in the middle | Real name or contact appears |
| Background sound | Place or time becomes visible |
| Subtitles | Names appear through automatic transcription |
| Editing mistake | Areas thought to be hidden remain |
Also check the purpose of publishing the video or audio.
The judgment changes depending on whether it is necessary as evidence, helps explanation, or merely conveys atmosphere. If the purpose is weak, explaining in text is safer.
Screen recordings have separate risks
Among videos, screen recordings require particular caution.
Screen recordings show browser tabs, bookmarks, notifications, email addresses, logged-in icons, filenames, clocks, and input history. Even if you intend to show only part of a document, the edge of the screen may retain a real-name environment.
| Things likely to appear | What becomes visible | Countermeasure |
|---|---|---|
| Browser tabs | Sites being viewed and work content | Keep only necessary tabs |
| Notifications | Real names, contacts, schedules | Turn off notifications |
| Bookmarks | Hobbies, workplace, admin pages | Use a dedicated browser |
| Filenames | Case names, personal names | Separate into a publication folder |
| Clock | Recording time and life rhythm | Crop if necessary |
Screen recording hands over the state of the device as-is.
If anonymity matters, record in a separate browser or separate user environment prepared for publication, not in your usual environment. After recording, recheck not only the video, but also the audio, subtitles, and filename.
Summary
Video and audio files have risks in both metadata and content.
In addition to recording date and time, location information, device information, editing software, and tag information, faces, backgrounds, reflections, voices, environmental sounds, notifications, and conversations become clues.
Even if metadata is removed, the contents of video and audio remain.
Before publication, create a publication copy and check metadata, video, audio, subtitles, and filename.
For high-risk activity, deciding not to release video or audio can also be a safety measure.
Related tools
ExifTool
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.
URL : https://exiftool.org/
MAT2
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.
FFmpeg
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.
URL : https://ffmpeg.org/