When you encounter errors like “video not supported,” “cannot open file,” or “unsupported codec,” the issue is usually not the video itself. Instead, it is related to how the video was encoded. Understanding video codecs is the key to solving these playback problems quickly and efficiently.
In this guide, you’ll learn what video codecs are, the difference between codecs and containers, and how to easily identify the codec used in any video file using free tools.
What Is a Video Codec?
A video codec is a technology used to compress and decompress digital video files. Compression makes videos smaller for storage and streaming, while decompression allows them to be played back smoothly.
If your device or media player does not support a specific codec, the video may not play correctly—or at all.
Some common video codecs include:
- H.264 (AVC)
- H.265 (HEVC)
- AV1
- VP9
- MPEG-4
- MPEG-2
- Xvid
- DivX
Modern platforms like YouTube and streaming services increasingly use H.265 and AV1 because they provide high quality at smaller file sizes.
Video Codec vs Container Format
Many users confuse codecs with file formats, but they are not the same.
Container Format (File Extension)
This is what you see at the end of a file name, such as:
- MP4
- MKV
- MOV
- AVI
- WMV
- WebM
The container acts like a wrapper that holds video, audio, subtitles, and metadata.
Codec (Inside the Container)
The codec determines how the video and audio are actually encoded inside that container.
For example:
- Two MP4 files may use different codecs
- One may use H.264, another may use H.265
That’s why a file may have a familiar extension but still fail to play.
How to Identify Video Codecs
Since codecs are hidden inside the file, you need special tools to view them. Below are the easiest and most reliable methods.
1. Check Video Codec Using VLC Media Player
VLC Media Player is one of the best tools for inspecting video files. It is free, open-source, and available on Windows, macOS, Linux, Android, and iOS.
Steps:
- Open your video in VLC
- Click Tools > Codec Information (Windows)
or Window > Media Information (macOS) - View details under the codec section
You will see:
- Video codec
- Audio codec
- Resolution
- Frame rate
- Bitrate
This is the fastest method for most users.
2. Use MediaInfo for Detailed Analysis
MediaInfo is a powerful tool that provides in-depth technical information about media files.
Features:
- Displays video and audio codecs
- Shows bitrate, frame rate, and resolution
- Supports batch file analysis
- Works on Windows, macOS, and Linux
How to use:
Simply install MediaInfo, then drag and drop your video file into the program. All technical details will be displayed instantly.
This tool is widely used by video editors and professionals.
3. Check Codec with QuickTime Player (Mac)
QuickTime Player is the default media player on macOS and offers a simple way to view file information.
Steps:
- Open the video in QuickTime Player
- Go to Window > Show Movie Inspector
- View codec and technical details
While not as detailed as MediaInfo, it is convenient for quick checks.
4. Advanced Option: FFmpeg (ffprobe)
For advanced users, FFmpeg’s tool ffprobe provides extremely detailed codec information.
It is commonly used in video production, streaming systems, and automation workflows. It can analyze almost any media file and display every technical detail available.
5. Other Video Inspector Tools
There are additional tools that can help identify codecs:
- VideoInspector (Windows)
- Codec analyzers and system diagnostic tools
However, many older tools are no longer updated and may not support modern codecs like HEVC or AV1. For best results, stick with VLC or MediaInfo.
Why Knowing Video Codecs Matters
Understanding codecs helps you:
- Fix “video not supported” errors
- Choose the right video converter
- Install missing codec packs if needed
- Improve video compatibility across devices
- Troubleshoot streaming or playback issues
As video technology evolves, modern codecs like AV1 and HEVC are becoming more common, especially for 4K and high-efficiency streaming.
Final Thoughts
Video playback issues are often caused by codec compatibility rather than file damage. Fortunately, identifying a video’s codec is easy with the right tools.
Whether you use VLC Media Player, MediaInfo, or QuickTime Player, you can quickly discover what codec a video uses and solve playback problems in minutes.
Once you understand how codecs and containers work together, managing video files becomes much simpler and far less frustrating.