mp42 vs ISOM

[Gregleto]

Hi all,

As simple as it seems, I just spent the last hour on Google trying to get this answer to no avail. Can someone provide a quick explanation of the difference between the codec IDs mp42 and ISOM? What can I infer from either one of these IDs when I see them in MediaInfo?

Thanks!

Gregleto

[Dust Signs]

MP42 stands for version 2 of the MP4 standard, while ISOM means that the file is compatible to the ISO base media file format (MPEG-4 Part 12), which does not really tell you anything since it is basically a generalization of MP42.

Dust Signs

[SeeMoreDigital]

I seem to remember that MP4box generates ISOM based .MP4 files and MP4creator and Quicktime Pro generate MP42 based .MP4 files...

[SnakEye]

any difference in quality/size between them both (mp42 vs isom)?
pros and cons of each? anything?

[LoRd_MuldeR]

There is no difference regarding quality/size, because this is about the container format specification, and not about the actual contents stored in that container.

Any MP4 files is an ISO Base Media file, because MP4 is based on ISO Base Media format - but not the other way around.

The so-called brand field of the 'ftyp' atom (box) indicates the specifications to which the particular ISO Base Media files conforms to. This should be "mp41" or "mp42", if the file conforms to MP4 version 1 or version 2, respectively.

It is somewhat analogous to the "FourCC" code stored in a RIFF files - which is "AVI_" for RIFF/AVI files, "WAVE" for RIFF/WAV files, and so on.

BTW: There also is a compatible_brands field in ISO Base Media files, which lists all the various "brands" to which the file is compatible to. Usually, for an MP4 (version 2) file, this will contain "isom", "mp41" and "mp42".

mpeg-4 part 14 is an instance of the more general iso/iec 14496-12:2004 (mpeg-4 part 12: Iso base media file format) which is directly based upon the quicktime file format.

https://i.imgur.com/l8J55xg.pnghttps://i.imgur.com/sOdnvDg.png

https://i.imgur.com/pVpADzX.png