The videos that we play on the Internet either locally on the computer or on any other device, can be encoded in different ways. Each method of coding implies some advantages and disadvantages, and there are better formats than others depending on the use we want to give the video. Thus, we have formats such as AVI, MP4, MKV, 3GP, Google WebM, etc …
When playing video on the Web, using a browser, the most widespread and best supported format by browsers, both mobile and desktop, is the MP4 format, and to be more exact, the MP4 / H format .264, which corresponds to files that normally have the extension .mp4. But:
Are all the .mp4 files the same?
The MP4 format – Parts, containers and extensions
When we talk about an .mp4 file or the MP4 format in general, what we are talking about is what is technically known as MPEG-4 Part 14. It is a standard format (ISO / IEC 14496-14) and is a container format of multimedia tracks. That is, this format defines how audio and video tracks (called data streams) in various formats can be contained in the file, and can even contain subtitles as well.
Within this container format, within the .mp4 file, the audio and video tracks may be encoded in various formats, as appropriate for the application to be given. Although in theory it supports many different formats (almost any) for these audio and video tracks, in practice the players of this format support only some specific types, the most frequent being:
Audio: AAC (Advanced Audio Codec, which when they are loose are files with extensions .m4a or .3gp), or the MP3 format.
Video: the different variants of the MPEG format.
MPEG or Moving Picture Experts Group is a group of “authorities” and manufacturers in the field of audio and video that came together at the request of ISO in the late 1980s to create file encoding standards for this type of multimedia information, and thus guarantee compatibility between media to be reproduced and reproductive devices. The first version of the standard, MPEG-1 came out in 1993, and since then there have been many new versions, and within these what they call “Parts”, which are specific aspects of the standard and also extensions to the specification for specific things, or improvements to the base format that they modify.
The most widespread version of this MPEG format is 4, or MPEG-4, which appeared at the end of 1998, and is what we know as MP4, due to the extension of its files. This version is divided into several sub-standards or “Parts” that describe certain issues of the format (for example, the 14 container, as I said at the beginning) and certain extensions.
Within the parts of the standard, part 10 describes an advanced coding format that is what we also know as H.264, but which is actually also called MPEG-4 Part 10 and what Blue-Ray discs used , for example. That is why in many Internet sites they talk about H.264 and MPEG-4 being the same. And it is true, but not quite, since in MPEG-4 parts 2, 12 or 14 also describe other compression formats that are MPEG-4, and the container format may also contain MPEG in earlier versions of lower quality such as MPEG -1 or MPEG-2.
