Concat multiple animated AVIFs?

[s1ddok]

Is it even possible? If so, will those AVIF be required to be encoded with the same settings?

Same resolution

[y-guyon]

Thank you for your interest in AVIF.

AVIF is a HEIF container wrapping AV1 frames.
Concatenating two AVIF files will not result in a compliant AVIF file, because it contains top-level boxes such as the FileTypeBox (the first chunk in the file) which must be unique in the file.

Assuming two similar AV1 payloads can be concatenated into a compliant AV1 bitstream (to be verified), the surrounding AVIF file must be adapted:

• The size of the MediaDataBox (to include the added encoded AV1 OBus)
• The SampleSizeBox and ItemLocationBox
• Fields such as the duration in the TrackHeaderBox

This list may not be exhaustive.

[maryla-uc]

You can try MP4Box from https://wiki.gpac.io/
This seems to work:

cp first.avif concatenated.avif
MP4Box -cat second.avif concatenated.avif

[s1ddok]

@maryla-uc but will it re-encode or truly concat?

[s1ddok]

@y-guyon thank you for the answering, do you think current public API of libavif allows it? I can't seem to find an easy way to concat multiple avif without re-encoding. My files are same setting, same size.

[maryla-uc]

MP4Box will not reencode as far as I'm aware. It's specifically designed to manipulate mp4/avif containers.

The libavif API on the other hand does not support manipulating the container. It will always reencode.

[y-guyon]

#2381 is a partial solution to avoid reencoding, but it would require other pieces to make it practical in libavif. I would suggest using container manipulation libraries as maryla-uc said, if that works for your use case.

[s1ddok]

got it thanks!

feel free to close this but I think this feature request might make sense