Utilities7 min read
Why Your Video Won't Play on Android: Containers, Codecs and Local Files
MP4 and MKV are containers, H.264 and AV1 are codecs, and the difference explains most playback failures. A practical guide to fixing them on Android.
24 articles
Utilities guides
Every article we have published on Utilities — how these apps work, the decisions behind them, and where their limits are.
Practical Android know-how: what is inside an MP4, MKV or MOV file, why a video will not play or its subtitles will not show, which codecs matter, and how picture-in-picture and app permissions work.
For collectors, the trading-card articles cover condition grading, centring and what grading services charge.
Covering 5 apps in this category.
Most-referenced guides
The articles in this category that other articles link to most often.
- Utilities10 min read
Video File Formats Explained: What Is Actually Inside an MP4, MKV or MOV
What a container really stores, how MP4, MKV, MOV and transport streams differ, and why remuxing fixes problems that re-encoding should not.
- Utilities4 min read
Hardware and Software Video Decoding Compared
What each does, why the power difference is so large, how to tell which one your device is using, and what to do when hardware decoding is unavailable.
All Utilities articles
- Utilities5 min read
Bulk Scanning a Card Stack Without Losing Track of Quantities
Cataloguing a stack of cards fails on quantities and variants, not on scanning. A bulk workflow that keeps counts, printings and corrections straight.
- Utilities5 min read
Photographing a Card So the Centring Measurement Means Something
A skewed or badly lit photo produces a confident, wrong centring ratio. How to capture front and back so the border measurement is worth trusting.
- Utilities5 min read
Picture-in-Picture on Android: When It Works and When It Does Not
PiP depends on the app declaring it, the device qualifying, and a per-app switch most people never see. A checklist for when the floating window never appears.
- Utilities5 min read
Why Two Apps Value the Same Card Differently
Two tools can price one card differently and both be defensible. What a value estimate is made of, why dispersion is normal, and how to read the gap.
- Utilities6 min read
Card Condition: From Near Mint to Damaged, and Who Decides
Marketplace condition labels and grader numeric scales are not the same system. What each level means and where the two disagree.
- Utilities7 min read
What Card Grading Costs, and What the Tiers Buy You
Grading is priced by declared value and turnaround. How the tier systems are structured, plus the costs people forget: postage, insurance and returns.
- Utilities6 min read
How to Measure Card Centring Before You Send Anything Off
Centring is measured as a left-right and top-bottom border ratio on both faces. How to photograph and measure it consistently at home.
- Utilities7 min read
How to Play MKV Files on Android When Nothing Opens Them
MKV is a container, so failure usually means an unsupported codec inside it rather than the file itself. How to work out which, and what to do next.
- Utilities6 min read
Is My Card Worth Grading? Working It Out Before You Pay
Grading only pays when the graded price minus fees and postage beats the raw price. How to run that sum honestly before sending anything.
- Utilities6 min read
Reverse Holo vs Holo: Which Printing Are You Holding?
Holo and reverse holo are different printings of the same card and price separately. How to tell them apart and why the distinction matters for value.
- Utilities7 min read
Subtitles Not Working on Android: A Checklist That Finds It
Missing subtitles usually come down to file naming, encoding, track selection or an unsupported format. Work through these in order.
- Utilities6 min read
When a Card Scanner Picks the Wrong Card
Reprints, regional variants and similar artwork all confuse image matching. How to spot a wrong match and correct it before it lands in a collection.
- Utilities4 min read
Android App Permissions Explained
Install-time, runtime and special permissions, how to review what your apps have, and why a permission list is only half the privacy picture.
- Utilities7 min read
Android Video Players Compared: Scope, Decoders and What Each One Is Actually For
Local playback, network streams, subtitles and speed control are different problems. How to pick an Android video player for what you actually watch.
- Utilities4 min read
Audio Codecs Explained
Lossy and lossless, AAC, MP3, FLAC, Opus and Vorbis, why multichannel audio fails on phones, and what passthrough actually does.
- Utilities4 min read
AV1 on Android: What Support Actually Means
What AV1 is, why decoder support matters more than the format itself, how Android's requirements changed, and what to do when a file will not play.
- Utilities4 min read
Frame Rate and Resolution Explained
What each controls, why bitrate matters more than either for perceived quality, and how judder, interlacing and scaling produce visible artefacts.
- Utilities4 min read
Google Play's Data Safety Section, Explained
What developers must declare, how collection differs from sharing, what the section does not tell you, and how to read it before installing anything.
- Utilities4 min read
Hardware and Software Video Decoding Compared
What each does, why the power difference is so large, how to tell which one your device is using, and what to do when hardware decoding is unavailable.
- Utilities4 min read
Remuxing and Transcoding: Know Which One You Need
Remuxing rewraps streams losslessly; transcoding re-encodes and loses quality. How to tell which your problem needs, and why remux is worth trying first.
- Utilities4 min read
Subtitle Formats Explained
SRT, ASS, WebVTT and image-based subtitles compared — what each can do, why some do not display, and the difference between embedded and external tracks.
- Utilities12 min read
Video Codecs Explained: Compression, Bitrate, Bit Depth and Why Newer Is Not Always Better
How video compression works, what bitrate and bit depth actually control, and why a newer codec means a smaller file and less certain support.
- Utilities10 min read
Video File Formats Explained: What Is Actually Inside an MP4, MKV or MOV
What a container really stores, how MP4, MKV, MOV and transport streams differ, and why remuxing fixes problems that re-encoding should not.
- Utilities7 min read
Why Your Video Won't Play on Android: Containers, Codecs and Local Files
MP4 and MKV are containers, H.264 and AV1 are codecs, and the difference explains most playback failures. A practical guide to fixing them on Android.