Practical codec and format help.

Browser tool

Inspect a media file

Check the real container, codecs, profile, bit depth, chroma, frame rate, audio properties and other streams without uploading the file.

Core library

Reference

Look up codecs, containers, bitrate, lossless audio, hi-res audio, Bluetooth codecs, and related concepts.

Side by side

Compare

Understand H.264 vs H.265, AAC vs Opus, FLAC vs WAV, Dolby vs DTS, and other common choices.

Workflows

Use cases

See why different formats make sense for preservation, remuxing, portable playback, discs and media libraries.

Decisions

Best formats

Choose formats for archiving, iPhone playback, streaming, and other real-world use cases.

Fix problems

Troubleshooting

Start here when a file will not play, has no sound, is too large, or behaves differently across devices.

Guided learning

Learn

Beginner, intermediate, and advanced paths for building a practical mental model of digital media.

Start here

What is a codec?

A simple entry point into the difference between codecs, containers, formats, and standards.

Understand the layers

Anatomy of a media file

See how containers, codecs, streams, extensions and metadata fit together.

MP3 encoding

LAME and bitrate control

Reference pages for LAME, ABR, cVBR, cVBRb, and how MP3 rate-control choices fit into compression.