APNG to AVIF Converter

Encoding: the APNG uses lossless DEFLATE per frame, like PNG; AVIF uses lossy or lossless AV1 intra-frame coding, and the download is an AVIF encoded with libavif (AV1) compiled to WebAssembly, at the quality you choose.

Bit depth: 8 bits per channel in the APNG; AVIF allows 8, 10 or 12 bits per channel, and the AVIF written here has 8 bits per channel.

Colour: RGB or an indexed palette in the APNG; AVIF supports YUV 4:4:4 or 4:2:0 with BT.709, Display P3 or BT.2020 primaries, HDR curves possible, written here as 8-bit sRGB.

Transparency: the APNG stores it as full alpha on every frame; the AVIF keeps it as an auxiliary AV1 image stored beside the colour image.

Animation: fcTL frame-control chunks with fdAT frame data after the first image; the AVIF holds one image, so only the first frame is converted.

Metadata: the APNG can carry the same text and ICC chunks as PNG; AVIF can carry EXIF, XMP and ICC stored as HEIF items, but nothing is copied across.

APNG extends PNG with animation frames. Unlike GIF it keeps full 24-bit colour and smooth 8-bit transparency, at the cost of larger files.

An APNG is a valid PNG with an acTL chunk announcing the frame count and loop count; each later frame is an fcTL chunk (size, offset, delay, blend and dispose rules) followed by fdAT data. Software that does not know APNG simply shows the first frame.

APNG files usually come from animated stickers (LINE and Discord among others), UI animations and Firefox-era web graphics.

AVIF uses the AV1 video codec for still images. It is the most efficient widely supported format, often half the size of JPEG, with HDR, wide colour and transparency, but encoding is slow.

An AVIF is a HEIF file, the same ISO base media boxes as MP4, with the brand 'avif'. The picture is an AV1 key frame stored as an image item, and its size, colour and pixel layout are item properties.

AVIF is the better choice for maximum compression on modern websites, while APNG suits high quality animated stickers and UI animations.

AVIF strengths: Often 50% smaller than JPEG; Excellent at low quality settings; Transparency, HDR and 10/12-bit colour. Drawbacks to weigh: Slow to encode, especially on phones; Not supported by some older software; Can smooth away fine texture at low quality.