Reference
Plain-English reference pages for the terms people run into when choosing, playing, converting, streaming, or archiving media.
Audio quality What actually matters?
Audio Quality Explained
What is Hi-Res Audio?
Hi-Res Audio Explained
Bluetooth audio codecs explained
What are Bluetooth Audio Codecs?
What is a Codec?
What is a Codec?
What is a container format?
How MP4, MKV, MOV and other wrappers hold codecs, tracks and metadata.
NOS DACs What is a non-oversampling DAC?
What is a NOS DAC?
NOS R2R DACs What is a ladder DAC?
What is a NOS R2R DAC?
DAC architectures explained
Multibit, oversampling, 1-bit, delta-sigma, R2R and PCM/DSD hybrid conversion.
What is AAC?
What is AAC?
What is Bitrate?
What is Bitrate?
Average bitrate (ABR)
How ABR differs from CBR and VBR, and why entropy coding affects bitrate demand.
LAME MP3 Encoder
Command-line MP3 encoding, VBR, ABR, and branch context.
Constrained VBR (cVBR)
VBR with a stricter minimum bitrate floor.
cVBRb bitrate boost
Optional boost behaviour for more conservative MP3 frame allocation.
What is DSD? (Direct Stream Digital Explained)
What is DSD?
What is DXD? (Digital eXtreme Definition Explained)
What is DXD?
What is LAME MP3?
What is LAME MP3?
What is FLAC?
Lossless audio, bit depth, sample rate, channels and actual format limits.
What is Lossless Audio?
What Is Lossless Audio?
What is MP3?
What is MP3?
What is SACD? (Super Audio CD Explained)
What is SACD?
What is THX?
Certification, playback technologies and why THX is not a codec.
Upsampling Does it improve audio?
What is Upsampling?
What is WAV?
What is WAV?
Why LAME MP3 still matters
Why LAME MP3 Still Matters
What is FFmpeg?
A multimedia toolkit, not a codec or file format.
What is Exact Audio Copy?
Why EAC is a CD-ripping application rather than a codec.
What is remuxing?
Change a container without re-encoding compatible streams.
What is transcoding?
Decode and encode media again for a new target.
What is sample rate?
44.1 kHz, 48 kHz and how sample rate differs from bitrate.
What is MKV?
Matroska is a container, not a video codec.
What is Opus?
A modern audio codec for speech, music and real-time communication.
What is H.264 / AVC?
Profiles, levels, bit depth, chroma, avc1 and x264.
What is H.265 / HEVC?
Main/Main 10, colour formats, hvc1/hev1 and x265.
What is AV1?
Main, High and Professional profiles, colour depth and chroma.
What is ALAC?
Apple Lossless bit depths, sample rates, channels and M4A relationship.
What is PCM?
Sample rate, bit depth, channels and uncompressed bitrate.
What is audio bit depth?
16-bit, 20-bit, 24-bit, valid bits and real converter precision.
What is chroma subsampling?
4:2:0, 4:2:2 and 4:4:4 versus 8/10/12-bit colour.
What is media metadata?
Tags, artwork, chapters, language and track flags.
What is a FOURCC code?
Codec tags, RIFF identifiers, MP4 sample entries and raw pixel-format codes.
Container capabilities compared
Tracks, subtitles, chapters, attachments, HDR, 3D, alternate edits, streaming and metadata.
What is MP4?
ISO-family container, tracks, codecs and why .mp4 does not identify the video codec.
What is MOV?
QuickTime container structure, tracks, ProRes relationship and MP4 ancestry.
What is AVI?
RIFF container, FOURCC codec tags, DivX/Xvid-era files and OpenDML.
What is WebM?
Matroska-derived web container for VP8/VP9 and Vorbis/Opus.
What is Ogg?
Open Xiph container/framing format; not the same thing as Vorbis.
What is AIFF?
Apple audio interchange format, PCM use and AIFF-C distinction.
What is Vorbis?
Open lossy audio codec, Ogg relationship, VBR and quality settings.
What is AC-3 / Dolby Digital?
Lossy 1.0–5.1 surround codec, DVD/Blu-ray rates and Dolby metadata.
What is E-AC-3 / Dolby Digital Plus?
Streaming-oriented Dolby codec with up to 7.1 discrete channels.
What is Dolby TrueHD?
Lossless home-theater codec, Blu-ray limits and Atmos relationship.
What is VP9?
Web video codec with 8/10/12-bit profiles and WebM relationship.
What is MPEG-2 Video / H.262?
DVD and broadcast video codec, profiles, levels and container distinction.
What is MPEG-4 Part 2?
The DivX/Xvid-era codec and why it is not H.264 or MP4.
What is Apple ProRes?
Professional intraframe codec family, 422/4444, bit depth and data rates.
What is MPEG-TS / M2TS?
Broadcast/Blu-ray transport container, packets, PIDs and contained codecs.
What is MXF?
Professional SMPTE media container for essence, timecode and metadata.
What is WavPack?
Lossless, lossy and hybrid audio compression with correction files.
What is Monkey's Audio / APE?
Actively maintained lossless audio format and APE tag distinction.
Codec profile vs level
Understand High@L4.1, Main 10, operating limits and decoder compatibility.
Frame rate, CFR, VFR and time base
23.976 vs 24, timestamps and why frame rate is not the same thing as a time base.
GOPs and keyframes
I, P and B pictures, long-GOP compression, seeking and editing behaviour.
Video colour signalling
RGB, YCbCr, full/limited range, BT.601/709/2020, transfer functions and HDR.
What is a MIME / media type?
Why video/mp4, audio/mpeg and codec strings describe different layers.
Codec and container compatibility
Which codecs commonly belong in MP4, MKV, WebM, Ogg, MPEG-TS and other containers.