In fact, Apple introduced its own extension chunk to PNG to enable parallel decoding, by splitting IDAT into two halves, put a zlib sync flush between them and

In fact, Apple introduced its own extension chunk to PNG to enable parallel decoding, by splitting IDAT into two halves, put a zlib sync flush between them and record the offset to the second half [1]. This kind of split is bulit into JPEG XL. [1] https://www.hackerfactor.com/blog/index.php?/archives/895-Connecting-the-iDOTs.html#c4809 https://www.hackerfactor.com/blog/index.php?/archives/895-Co...