AVIF

AVIF is AV1 intra-frame coding stored in a HEIF/ISO-BMFF container. It is the format to reach for when you want the smallest lossy images that every current browser can display, and it also gives you 10- and 12-bit depth, HDR signalling, alpha and animation. It is a poor choice for lossless archival, and encoding is slower than JPEG or WebP.

The container is the same family as HEIC; the payload is the AV1 video codec, so any AV1 encoder can in principle produce AVIF images.

Strengths and weaknesses

Strengths

• Very good lossy compression on photos and on flat graphics. At low and medium bitrates it beats JPEG and WebP by a wide margin; against JPEG XL it usually produces smaller files at web-delivery quality, while JPEG XL pulls ahead at very high quality and in lossless.
• 8-, 10- and 12-bit, 4:2:0 / 4:2:2 / 4:4:4 / monochrome, wide gamut and HDR signalling (PQ, HLG), ICC or CICP colour, and a separate alpha plane.
• Animation using real inter-frame video coding, which makes it a far better animated format than GIF or animated WebP for most clips.
• Royalty-free, and supported by every current browser.

Weaknesses

• Slower encoding than JPEG, WebP or JPEG XL. libaom at its slowest speeds (-s 0–3) and on large images takes seconds to minutes per file.
• Weak lossless mode. It is usually larger than lossless WebP or JPEG XL, and sometimes larger than PNG.
• No JPEG-style progressive decode: a plain AVIF shows nothing until enough of the file has arrived. Layered “progressive” files exist in the AVIF 1.2 spec and avifenc --progressive can write them, but check your target decoders before relying on them.
• Smooth gradients can band and fine texture can smear at low bitrates, and 4:2:0 bleeds saturated colour edges and small coloured text.
• Very large images need tiling or a grid, which costs a little efficiency and can leave faint seams.

Support

Platform	Still AVIF	Notes
Chrome	85+	Other Chromium browsers follow their Chromium version
Firefox	93+	Animated AVIF from Firefox 113
Edge	121+
Safari	16.4+ on macOS, 16.1+ on iOS	Safari 16.1–16.3 on macOS worked only on Ventura
Android system decoder	Android 12+ (8-bit)	10-bit decoding is optional per device

Browser versions are from MDN’s AVIF data and Android’s supported media formats. Desktop OS thumbnailers, editors and messaging apps are patchier than browsers; see image and audio support for how to check a given file.

Profiles matter less than they used to, but they still bound what a conservative decoder accepts. The Baseline brand (MA1B) is AV1 Main profile (8/10-bit, 4:2:0 or monochrome) at level 5.1 or lower; the Advanced brand (MA1A) is High profile (adds 4:4:4) up to level 6.0. Larger images are built from a grid of tiles.

Encode with avifenc

avifenc from libavif is the standard encoder. It takes PNG, JPEG or Y4M input and calls an AV1 backend (libaom, SVT-AV1 or rav1e, whatever your build includes).

avifenc -q 65 -s 4 input.png output.avif

-q and -s are the two knobs you will actually turn. The defaults are -q 60 and -s 6. Pick the quality by eye at a fast speed, then encode the final file at -s 4 or slower; speeds below 4 cost a lot of time for a small gain.

Option	What it does
-q 0..100	Colour quality; 100 is lossless AV1 coding. Not comparable between backends or libavif releases.
--qalpha 0..100	Alpha quality, inherited from -q unless set. Use --qalpha 100 if the alpha edge must stay clean.
-s 0..10	Speed; lower is slower and smaller. Default 6.
-d 8/10/12	Output bit depth; follows 8-bit input by default. Use 10 for HDR and high-bit-depth sources. -d 10 is also common for 8-bit sources because it reduces banding in smooth gradients.
-y 444/422/420/400	Chroma format. auto gives 4:4:4 for PNG, keeps the subsampling of a JPEG and uses 4:0:0 for greyscale PNG.
--sharpyuv	Sharper RGB→4:2:0 conversion; only does anything with -y 420.
-c aom/svt/rav1e	Choose the backend.
-j N	Worker threads (default all).
-a KEY=VALUE	Pass a backend option, e.g. -a tune=iq. libaom keys can be limited to one plane with color: or alpha:.
-l	Lossless: sets RGB-identity, full-range, 4:4:4 defaults.
--cicp P/T/M, --icc	Signal colour primaries/transfer/matrix or attach an ICC profile.

Chroma: 4:4:4 or 4:2:0

avifenc keeps 4:4:4 for PNG input, and libaom handles 4:4:4 well, so the extra chroma usually costs little. Keep it for screenshots, UI, line art and coloured text, where 4:2:0 visibly bleeds colour. Use -y 420 (plus --sharpyuv) when you need the smallest photo files or files that stay within the Baseline brand and AV1 Main profile that hardware decoders support.

Tuning

Since libavif 1.4.0, avifenc with libaom 3.13 or newer encodes still images (YUV, not RGB-matrix) with tune=iq by default, and maps -q to quantizers with a formula designed for it. tune=iq is libaom’s still-image mode, added in 3.12: it was developed with SSIMULACRA2 as a guide and checked visually, and uses Variance Boost, adaptive CDEF and quantization matrices. Alpha is encoded with tune=psnr, because tune=ssim causes ringing on alpha.

The older recipe of -a tune=ssim -a end-usage=q -a cq-level=… is obsolete: use -q and leave the tune alone. Because tune=iq was shaped around SSIMULACRA2, check comparisons against other tunes by eye as well.

Backends

Backend	Notes
libaom	The default and the usual best choice for stills: full chroma and bit-depth support, tune=iq, and the most intra-coding work behind it.
SVT-AV1	Faster, but libavif’s SVT adapter is 4:2:0 only, 8/10-bit. A PNG defaults to 4:4:4, so -c svt without -y 420 fails with “Only support 420 now”. The libaom -a keys do not apply.
rav1e	Works, but is slow for stills and lacks libaom’s still-image tuning.

libheif’s heif-enc --avif is a second frontend with the same backends and its own defaults (quality 50); its plugin parameter tables are in the reference below. AVIF is also writable from FFmpeg and ImageMagick, which go through libavif or libheif.

Alpha, HDR and animation

• Alpha is stored as a separate monochrome AV1 image, so it has its own quality (--qalpha). Use -p only if you intend premultiplied (associated) alpha.
• HDR: keep the source’s real transfer function and primaries (--cicp 9/16/9 for PQ BT.2020, 9/18/9 for HLG) and encode at 10 bit or more. Tagging SDR pixels as PQ does not make them HDR. In builds with gain-map support, avifenc converts gain maps embedded in JPEG input (--qgain-map, --ignore-gain-map).
• Animation: pass several PNGs with --fps, or pipe Y4M from FFmpeg: ffmpeg -i in.mp4 -pix_fmt yuv420p -f yuv4mpegpipe - | avifenc --stdin out.avif. Firefox plays animated AVIF from version 113.

Pitfalls

• A lossless AV1 stream does not make the file lossless: RGB→YUV conversion and 4:2:0 are lossy unless you use -l.
• avifenc copies Exif, XMP and ICC from PNG and JPEG input and turns the Exif orientation into AVIF irot/imir transforms. Use --ignore-exif, --ignore-xmp or --ignore-icc to drop them; dropping the ICC profile of a wide-gamut source changes its colours.
• Re-encoding an AVIF from a previous lossy AVIF compounds loss; keep the original source.

Other encoders

Any AV1 encoder can produce AVIF; see aomenc, SVT-AV1 and rav1e. Rachel Barker’s tinyavif is a minimal AVIF encoder written to show how AVIF and AV1 work, not for production.

Related pages

• AV1 is the video codec underneath.
• JPEG XL has lossless JPEG recompression and a stronger lossless and high-quality story.
• WebP is the older, faster, 8-bit-only alternative.
• HEIC uses the same container with HEVC.

Full option reference

The tables below are the full avifenc and libheif AVIF plugin parameter references. Reading option tables explains the Default column.

avifenc 1.4.2 complete parameter reference

INPUT to —target-size

Parameter / aliases	Type or accepted values	Default	Purpose and constraints
INPUT	path(s)	required	JPEG, PNG or Y4M input. Several inputs make an animated sequence, or the layers/cells with —layered/—grid.
OUTPUT	path	required, unless —output is used	Output .avif. Taken from the last positional argument unless —output is given.
--help, -h	action	not requested	Print usage and the compiled-in codec versions.
--version, -V	action	not requested	Print the libavif and codec library versions.
--qcolor, -q, --qcolor:u, --qcolor:update, -q:u, -q:update	integer 0–100	60	Colour quality, 0–100. 100 is lossless AV1 coding, though RGB→YUV conversion can still be lossy. The :u forms apply only to the inputs after them.
--qalpha, --qalpha:u, --qalpha:update	integer 0–100	same as qcolor	Alpha quality, 0–100. Follows —qcolor unless set.
--speed, -s	0–10, default or d	6	Encoder speed, 0 (slowest) to 10, or default/d for the codec’s own default. Slower is smaller.
--jobs, -j	positive integer or all	all detected CPUs	Worker threads, or all. What it controls depends on the codec.
--no-overwrite	flag	false	Fail instead of replacing an existing output file.
--output, -o	path	final positional filename	Output path, instead of the last positional argument.
--lossless, -l	flag	false	Set lossless defaults: quality 100, full range, 4:4:4 and identity matrix. Warns when the input can’t be stored losslessly.
--depth, -d	D[,extension]	input-dependent	Output bit depth, 8, 10 or 12. A second value (8,8 / 12,4 / 12,8) adds a hidden extension image for 16-bit output. Y4M keeps its own depth.
--yuv, -y	auto, 444, 422, 420, 400	auto	Chroma format: auto, 444, 422, 420 or 400. auto keeps a JPEG’s subsampling, uses 400 for greyscale PNG and 444 otherwise; Y4M keeps its format.
--premultiply, -p	flag	false	Multiply colour by alpha before encoding and mark alpha as premultiplied. Changes pixel values.
--sharpyuv	flag	false	Sharper RGB→4:2:0 conversion (needs libsharpyuv). No effect on Y4M or non-4:2:0 output.
--stdin	flag	false	Read one stream (Y4M by default) from standard input. No other input paths are allowed; the output path is still required.
--input-format	auto, jpg, jpeg, png, y4m	auto for paths; y4m for stdin	Force the input type: jpeg/jpg, png, y4m or auto. Needed only when the extension is misleading.
--cicp, --nclx	P/T/M integers	2/2/6 before input-specific handling	Colour primaries/transfer/matrix as three numbers (H.273); 2 means unspecified. Tags the file; samples are not converted.
--range, -r	full/f or limited/l	full for JPEG/PNG; retained for Y4M	YUV range, full or limited. Y4M input keeps its own range.
--target-size	positive bytes	disabled	Aim for this file size in bytes by searching over quality. Up to 7× slower; conflicts with fixed —qcolor/—qalpha.

—progressive to —irot

Parameter / aliases	Type or accepted values	Default	Purpose and constraints
--progressive	flag	false	Write a two-layer image that can render progressively from one input. Needs —qcolor of at least 10; support is limited.
--layered	flag	false	Encode two to four inputs as layers of one image. Not an animation.
--grid, -g	columns x rows	disabled	Write a grid of COLSxROWS cells, from identical inputs or one image split evenly.
--codec, -c	build-specific encoder ID	auto	Pick the AV1 encoder, for example aom, rav1e or svt. Decoder-only IDs can’t encode.
--exif	payload path	preserve input metadata if present	Use this Exif payload instead of any embedded Exif.
--xmp	payload path	preserve input metadata if present	Use this XMP payload instead of any embedded XMP.
--icc	profile path	preserve input profile if present	Use this ICC profile instead of any embedded one. Tags the image; samples are not converted.
--timescale, --fps	positive integer	30; may inherit Y4M timing	Sequence ticks per second. With one-tick frames this is the frame rate. Y4M frame rate is used if unset.
--creation-time	nonnegative Unix seconds	0: use modification time	Sequence creation time in Unix seconds. 0 uses the modification time.
--modification-time	nonnegative Unix seconds	0: use current time	Sequence modification time in Unix seconds. 0 uses the current time.
--keyframe, -k	integer	0: disabled	Maximum keyframe interval for sequences, in frames. 0 disables the limit.
--ignore-exif	flag	false	Drop embedded Exif.
--ignore-xmp	flag	false	Drop embedded XMP.
--ignore-icc, --ignore-profile	flag	false	Drop the embedded ICC profile.
--ignore-gain-map	build-gated flag	false	Drop an embedded JPEG gain map. Needs a libavif built with gain-map conversion.
--qgain-map	build-gated integer 0–100	60	Gain map quality, 0–100. Needs a gain-map build; takes no :u form.
--pasp	H,V positive spacing	absent	Pixel aspect ratio as H,V. Metadata only.
--crop	x,y,width,height	absent	Clean-aperture crop as x,y,width,height. Applied at display time; pixels are not removed.
--clap	eight rational components	absent	Clean aperture as eight numerator/denominator values: width, height, horizontal offset, vertical offset.
--irot	integer 0–3	absent	Rotation in 90° steps anticlockwise (0–3). Stored as a transform.

—imir to —

Parameter / aliases	Type or accepted values	Default	Purpose and constraints
--imir	0 or 1	absent	Mirror axis: 0 top-to-bottom, 1 left-to-right. Stored as a transform.
--clli	MaxCLL,MaxPALL	absent	MaxCLL,MaxPALL content light level metadata. Doesn’t make the image HDR.
--repetition-count	nonnegative integer or infinite	infinite	How many times a sequence plays, or infinite.
--tilerowslog2, --tilerowslog2:u, --tilerowslog2:update	integer 0–6	0 before automatic tiling	log2 of the number of tile rows (0–6). Setting it switches to manual tiling.
--tilecolslog2, --tilecolslog2:u, --tilecolslog2:update	integer 0–6	0 before automatic tiling	log2 of the number of tile columns (0–6). Setting it switches to manual tiling.
--autotiling, --autotiling:u, --autotiling:update	flag	true	Choose AV1 tiling automatically. This is the starting mode; it is separate from a HEIF grid.
--min, --min:u, --min:update	deprecated quantizer 0–63	0	Deprecated minimum quantizer (0–63). Use —qcolor.
--max, --max:u, --max:update	deprecated quantizer 0–63	63	Deprecated maximum quantizer (0–63). Use —qcolor.
--minalpha, --minalpha:u, --minalpha:update	deprecated quantizer 0–63	0	Deprecated minimum alpha quantizer (0–63). Use —qalpha.
--maxalpha, --maxalpha:u, --maxalpha:update	deprecated quantizer 0–63	63	Deprecated maximum alpha quantizer (0–63). Use —qalpha.
--scaling-mode, --scaling-mode:u, --scaling-mode:update	positive N[/D]	1/1	Frame or layer scaling as N[/D], for example 1/2.
--duration, --duration:u, --duration:update	positive clock ticks	1; may inherit Y4M timing	Frame duration in timescale ticks for the following inputs. Applies with or without :u.
--advanced, -a, --advanced:u, --advanced:update, -a:u, -a:update	KEY[=VALUE], repeatable	none	Pass KEY[=VALUE] straight to the codec, for example -a tune=ssim. Repeatable. Keys are the codec’s own.
--mini	build-gated flag	false	Compact-header writer. Needs a build with AVIF_ENABLE_EXPERIMENTAL_MINI; not in current binaries.
--	separator	not used	End of options; later arguments are filenames.

libheif AVIF plugin references

Plugin parameters for heif-enc --avif -e aom|rav1e|svt, set with -p NAME=VALUE. The full heif-enc frontend reference is on the HEIC page.

libheif AOM plugin parameters

Parameter / aliases	Type or accepted values	Default	Purpose and constraints
realtime	boolean	false	Use libaom’s realtime mode instead of good-quality mode. Faster, larger.
speed	integer 0–9	6	libaom cpu-used, 0 is slowest. Realtime mode changes what the values mean.
threads	integer 1–64	CPU count, max 64 (4 if undetectable)	Worker threads.
quality	integer 0–100	50	Colour quality.
lossless	boolean	false	Lossless colour coding.
chroma	420, 422 or 444	420	Chroma subsampling. Lossless RGB needs 444.
tune	auto, psnr, ssim or iq	auto	auto picks by image type (still, sequence, alpha). iq can’t be combined with lossless.
min-q	integer 0–63	0	Lowest quantizer index the encoder may use.
max-q	integer 0–63	63	Highest quantizer index the encoder may use.
alpha-quality	integer 0–100	same as quality	Alpha quality. Follows the colour quality if unset.
alpha-min-q	integer 0–63	same as min-q	Lowest alpha quantizer. Follows min-q if unset.
alpha-max-q	integer 0–63	same as max-q	Highest alpha quantizer. Follows max-q if unset.
lossless-alpha	boolean	false	Code alpha losslessly while colour stays lossy.
auto-tiles	boolean	false	Let libaom choose the tile layout.
enable-intrabc	boolean	true	Allow intra block copy, which helps screen content.

libheif rav1e plugin parameters

Parameter / aliases	Type or accepted values	Default	Purpose and constraints
speed	integer 0–10	8	rav1e speed, 0 is slowest.
threads	integer 1–16	4	Worker threads.
tile-rows	1, 2, 4, 8, 16, 32, 64	4	Number of tile rows (a count, not the log2 value avifenc uses).
tile-cols	1, 2, 4, 8, 16, 32, 64	4	Number of tile columns (a count, not log2).
chroma	420, 422 or 444	420	Chroma subsampling.
min-q	integer 0–255	0	Lowest quantizer rav1e may use.
quality	integer 0–100, -q only	50 (set by heif-enc)	Set with heif-enc -q and mapped to a 0–255 quantizer. Not in the parameter list, so -p quality= is rejected.
lossless	not settable	unsupported	No lossless mode: -L falls back to lossy with a warning, and -p lossless= is rejected.

libheif SVT-AV1 plugin parameters

Parameter / aliases	Type or accepted values	Default	Purpose and constraints
speed	integer 0–13	12	SVT-AV1 preset. Lower is slower and smaller.
threads	integer 1–16	4	Thread hint, not a guaranteed worker count.
tile-rows	1, 2, 4, 8, 16, 32, 64	4	Number of tile rows.
tile-cols	1, 2, 4, 8, 16, 32, 64	4	Number of tile columns.
quality	integer 0–100	50	Quality, converted to a QP unless qp is set.
lossless	boolean, SVT ≥3	false	Lossless coding, SVT-AV1 3 or newer. heif-enc -L on RGB input (PNG, JPEG) exits with ‘Unsupported encoder parameter’ because it also sets chroma=444, which this plugin lacks.
qp	integer 0–63	unset: derived from quality	Quantizer. Overrides quality when set.
min-q	integer 0–63	0	Lowest quantizer SVT-AV1 may use.
max-q	integer 0–63	63	Highest quantizer SVT-AV1 may use.
tune	vq, psnr, ssim, iq, ms-ssim	psnr	SVT-AV1 tune: vq, psnr, ssim, iq, ms-ssim. iq and ms-ssim need SVT-AV1 4 or newer.
chroma	fixed 420	420	Not a parameter: the plugin always encodes YCbCr 4:2:0, and -p chroma= is rejected.