À propos des fichiers Y4M

Y4M (YUV4MPEG2 · Format vidéo)

Lancement 2002 Par MPlayer developers

YUV4MPEG2 (.y4m) est un format de fichier pris en charge par KaijuConverter pour l’archivage, l’échange professionnel et la conversion multiplateforme.

Famille

Video Files

Extension

.y4m

Type MIME

video/x-raw-yuv

Utilisable comme

Entrée Sortie

L'histoire

COMMENT Y4M
A VU LE JOUR.

Y4M — YUV4MPEG2 — is a raw uncompressed video container used almost exclusively by codec developers. The format is brutally simple: a one-line ASCII header (`YUV4MPEG2 W1920 H1080 F30:1 Ip A1:1 C420 XCS=100`), then alternating frames prefixed with `FRAME\n` markers, then raw YUV pixel data. No compression, no timecodes beyond the framerate — a video codec’s perfect ground-truth input.

X264, x265, SVT-AV1, every video codec encoder on Earth accepts .y4m as test input. A 10-second 1080p Y4M weighs 600 MB uncompressed, which is the entire point: no prior codec decisions have been baked in, so codec-quality comparisons use Y4M as the source of truth.

CURIOSITÉS ET
ANECDOTES.

Every video codec benchmark on the planet uses Y4M as ground-truth source — x264, x265, AOM AV1, SVT-AV1.

Y4M's header is one ASCII line — trivially parseable and human-readable.

10 seconds of 1080p Y4M is about 600 MB — codec developers work with terabytes of Y4M test data.

The `FRAME\n` marker between frames is deliberately simple — parsers can seek by scanning.

Y4M's simplicity is why codec papers always cite Y4M inputs: no ambiguity about pre-processing.

POINTS FORTS ET
LIMITES.

Points forts

Uncompressed raw YUV — codec benchmark truth.
Dead-simple header.
Universal codec development support.

Limites

Enormous file sizes.
Development-only — not for consumption.
No metadata beyond basic stream params.

Tailles et poids typiques

10 sec 1080p Y4M

~600 MB

1 min 4K Y4M

~14 GB

Spécifications techniques

MIME type: video/x-yuv4mpeg2
Extension: .y4m
Pixel format: YUV 4:2:0, 4:2:2, 4:4:4
Header: ASCII single line

CONVERTIR DEPUIS
Y4M

y4m jpg y4m png y4m webp y4m gif y4m bmp y4m mp4 y4m mov y4m mkv y4m avi y4m webm y4m flv y4m wmv y4m mpeg y4m 3gp y4m mp3 y4m wav y4m flac y4m aac y4m m4a y4m ogg y4m opus y4m wma y4m ogv y4m m4v y4m ts y4m asf y4m dv y4m f4v y4m h264 y4m h265 y4m m2v y4m mjpeg y4m mxf y4m rm y4m rmvb y4m divx y4m nut

CONVERTIR EN
Y4M

mp4 y4m mov y4m mkv y4m avi y4m webm y4m flv y4m wmv y4m asf y4m dv y4m f4v y4m h264 y4m h265 y4m m2v y4m mjpeg y4m mxf y4m rm y4m rmvb y4m divx y4m nut y4m mpeg y4m 3gp y4m ogv y4m vob y4m m4v y4m ts y4m m2ts y4m mts y4m swf y4m mpg y4m

Cas d'usage courants

Video quality benchmarking, uncompressed intermediate, codec testing