main profile image sequence

[dibbitson]

Hi,

Is a simple inter frame encoding supported? ie IPPPPP.

I can do a main profile encode with all I frames, or mainstillpicture, but any reference frames seems to not work.

Any ideas?

Thanks

[silverbacknet]

That it works at all is mostly an accident; libheif doesn't support image sequences currently.

[farindk]

Image sequence coding is currently not supported at all and there are also no plans to work on it until someone can convince me that this is useful for anything :-)

Maybe decoding, but until now I did not come across any sequence files.

[dibbitson]

Ha well it's a happy accident. Seems to work well. On Mac at least preview has no problem decoding all the imagery.

I have a valid use case ;) I'm sending this imagery in an environment with constrained bandwidth. The space savings gained by being able to do P frames would be very nice.

I might take a look at adding support myself if I can find the time -- from my glance at the spec and libheif code it shouldn't be too much of a change (famous last words). But I'm still not entirely sure of the details yet.

Thanks!

[farindk]

I'm still not sure what you are actually showing, because libheif cannot produce sequences. It can produce files with multiple images, but these are not sequences (HEIF standard section 7 "Image Sequences").

[silverbacknet]

The thing is, why heif when you have mp4?

I personally would like to see it because layering static (or even separately moving) areas over a moving image is so powerful for retaining hard edges, like text layers. It's a super common use case in web pages, but there's already HTML and Javascript and SVG for that. Some benefit would transfer to moving it to a constrained file format, much like layering in general can benefit from going to a single PDF.

But is that a sufficient use case to interest anyone? Probably not. Just encoding any plain video to mp4 is plenty for nearly all use cases.

[farindk]

@silverbacknet It's also the same codec. Whether you put h265 or av1 into a HEIF container or an MP4 container does not matter at all.

[dibbitson]

Ah I see -- ok that makes sense. That's what I'm seeing then (a file with multiple images).

@silverbacknet We considered MP4 (and unfortunately I can't go into detail) but heif provides a nice solution for our workflow.