You try to play a video on your TV and get a black screen. Or you’re about to re-encode a clip and don’t want to recompress something that’s already fine. Or a download has no sound on your phone but works on your laptop. All three questions have the same answer hiding inside the file: its media info. Read that, and you stop guessing.
This guide walks through everything media info contains, why each piece matters in practice, and how to read it from the media info viewer. The file you inspect stays on your own device the whole time.
What “media info” actually includes
Media info is the technical breakdown of a video or audio file: the wrapper it uses, the codecs inside it, and the measurements of each track. Pulled apart, a typical video file reports a container format, one or more video and audio streams, and for each stream the codec, plus numbers like resolution, frame rate, bitrate, duration, channel count, and sample rate.
Here’s what each term means in plain language:
- Container — the outer file format, the part you see in the extension like
.mp4,.mkv, or.mov. It holds the video and audio together and keeps them in sync. - Codec — the method used to compress a stream so it isn’t enormous. Video codecs include H.264, H.265 (also called HEVC), VP9, and AV1. Audio codecs include AAC, MP3, and Opus.
- Resolution — the width and height of the picture in pixels, such as 1920 by 1080.
- Frame rate — how many still frames play per second, like 24, 30, or 60.
- Bitrate — how much data is used per second of playback. More data usually means more detail and a bigger file.
- Duration — the running length of the file.
- Audio tracks and channels — how many separate audio streams the file carries, and how many channels each one has (mono is 1, stereo is 2, surround is 6).
- Sample rate — how finely the audio was captured, commonly 44,100 or 48,000 times per second.
Container versus codec: the distinction that explains most problems
The single most useful idea here is that the container and the codec are two different things, and people confuse them constantly. The container is the box. The codec is how the contents were packed into that box.
Picture a cardboard box with items wrapped inside. The box is the container: the .mp4 or .mkv. The wrapping method is the codec. You can have the same item wrapped the same way inside two differently shaped boxes, and you can have two boxes of the same shape holding items wrapped in completely different ways.
This matters because a file might fail to play for a container reason or a codec reason, and the fixes are not the same:
- If the container is unusual but the streams inside use common codecs, you can often just repackage the file into a friendlier wrapper. That’s fast and loses no quality because nothing gets recompressed.
- If the codec itself isn’t supported by your device, you have to actually re-encode, which recompresses the video into a different codec. That’s slower and costs a little quality.
Knowing which situation you’re in before you start saves you from running a slow, lossy re-encode when a quick repackage would have done.
Why this matters in the real world
A video that won’t play is usually a codec problem
When a clip plays on your computer but not on your TV, streaming stick, or phone, the file is almost never broken. The issue is that your computer runs flexible software that understands a wide range of codecs, while a TV or phone has a fixed, built-in set. Hand it a codec it doesn’t recognise, often newer ones like H.265 or AV1, and it shows nothing.
Reading the media info tells you the exact video and audio codecs in the file. Once you know it’s, say, H.265 audio on a device that only does H.264, the path forward is obvious: re-encode the video stream to a codec the device supports.
Checking before you re-encode
Re-encoding takes time and shaves a little quality off every pass. Before you commit to it, the media info answers two questions. First, is the codec already widely supported, meaning you might only need to repackage rather than re-encode? Second, what’s the current bitrate and resolution, so you can pick sensible settings for the new file instead of guessing? Going in with the numbers in front of you beats trial and error.
Confirming bitrate and quality
If you’ve been handed a file and told it’s “high quality,” the media info lets you check. The resolution tells you the picture dimensions, and the bitrate tells you how much data backs up that resolution. A 1080p file with a very low bitrate has been squeezed hard and will look soft. Comparing the bitrate of two versions of the same footage is a fair, quick way to see which one kept more detail.
How to read each track’s details
Open a file in the viewer and you get a structured report, usually split into the container at the top and then each stream listed separately.
Start with the container line. It confirms the wrapper format and gives you the overall duration and total bitrate. This is your at-a-glance summary.
Then read each video stream. A typical entry lists the codec name, the resolution, the frame rate, and that stream’s bitrate. The codec is the first thing to look at when diagnosing a playback failure. The resolution and frame rate tell you what you’re actually working with, which is handy when a file’s name claims one thing and the contents say another.
Then read each audio stream. Files can carry more than one audio track, for example a main mix plus a commentary or a second language. For each, you’ll see the audio codec, the channel count, and the sample rate. If a video plays but has no sound on a particular device, this is where you look: either the audio codec isn’t supported, or the track has more channels (like 5.1 surround) than the device can output.
The table below maps each detail to the question it answers.
| Detail | The question it answers |
|---|---|
| Container | Why won’t this wrapper open here? |
| Video codec | Why is the picture missing or erroring? |
| Resolution and frame rate | What am I really working with? |
| Bitrate | How much quality is in this file? |
| Audio codec and channels | Why is there no sound, or wrong sound? |
| Duration | Is the whole file here, or was it cut short? |
Copying the report
Once you’ve read what you need, you’ll usually want to keep it. The viewer lets you copy the full media info report as text in one action, which is handy when you’re filing a support ticket, asking for help in a forum, or noting down the source settings before a re-encode so you can match or improve on them. Having the exact codec names and numbers in hand makes those conversations far shorter than “my video won’t play.”
The short version
A video that won’t behave is rarely a corrupt file. It’s a mismatch between what the file contains and what your device can handle, and media info shows you exactly where the mismatch is. Read the container and codec first, check the audio track if the sound is the problem, and note the bitrate and resolution before any re-encode. The whole inspection runs locally in your browser, so even large recordings or private footage never leave your device. If you also need to confirm what an unlabeled media file even is, identifying its real type is the natural first step before reading its tracks.