I am wondering if there is a maximum width or a limitation regarding aspect ratio when it comes to MP4.
I frequently have to create LED banners for football stadiums with formats like 17280x96px. That's no problem with MOVs or AVIs rendered from AEs Render Queue. But this time have to deliver as MP4 and it seems I can't go bigger than 16384x40px with h.264 codec and not bigger than 16384x96 with HEVC (h.265).
If I am right and there is a limitation can someone give a reliable source that confirms that?
Most of the codecs have some kind of restritions and as you mentioned h264 and h245 have resolution restriction. And values that you reached are - for now - maximum values that you can use.
It seems as an issue but I think that you make little mistake in your workflow buy preparing your file as a one wide file. Most of banners of that kind are distributed by media servers and systems based on widelly known standards (full HD or even less) and being played as one by using soething alled pixel maps. So to make your job easier for future or even possible - reaching wider resolutiuons than codec let you - ask tech support guys that are maintaining those foodball stadium banners about exact way of distribution (pixel map tempate) and prepare your footrage that way.
Similar issue from several weeks ago: https://community.adobe.com/t5/After-Effects/Exporting-large-files-in-AE/td-p/10375300
As for specs of codecs you can find those in patent papers/specs for ITU or Wikipedia (in most cases that is jus copied from patent papers. And there you have it:
- wiki https://en.wikipedia.org/wiki/Advanced_Video_Coding
- itu https://www.itu.int/rec/T-REC-H.264
- wiki https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding
- itu https://www.itu.int/rec/T-REC-H.265