No, this is incorrect. It's up to the implementation of the muxer to determine where index information goes, which is typically at the end of the file. This is

No, this is incorrect. It's up to the implementation of the muxer to determine where index information goes, which is typically at the end of the file. This is simply because writing a file is a single pass operation, and you don't know the contents of the atom until you've gone through the all the data for each stream. Many muxers provide an option to place it at the beginning of the file by adding padding and overwriting it afterward, which solves the progressive streaming problem.