CHCodec Help
Learn

Understand how media files fit together

Start with the layers people most often mix up: codec, container, extension, encoder, application, metadata and conversion.

A useful rule

A name such as MP4, LAME, EAC or FFmpeg only makes sense once you know what kind of thing it is.

CodecContainerEncoderApplication
Start here

Anatomy of a media file

See how filename, extension, container, streams, codecs, subtitles and metadata fit together.

 Software vs format

Codec vs encoder vs application

Why LAME, EAC, FFmpeg, VLC, x264 and H.264 are not the same kind of thing.

 Common confusion

Codec vs file extension

Why .mp4 or .mkv cannot tell you everything about the media inside.

 Conversion

Does converting lose quality?

Understand remuxing, transcoding and why MP3-to-FLAC does not restore lost information.

 Containers

What is remuxing?

Change the package while keeping compatible encoded streams unchanged.

 Codecs

What is transcoding?

Decode and encode media again to change codec, bitrate, size or compatibility.

Profiles and levels

Read codec labels such as H.264 High@L4.1 and HEVC Main 10 correctly.

Video timing

Frame rate, CFR/VFR, timestamps and time bases.

How inter-frame video works

GOPs, keyframes, I/P/B pictures and seeking.

How video colour is described

YCbCr, chroma, range, primaries, transfer functions and HDR signalling.